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Pool Calcium Hardness and Scale

Problems caused by high calcium hardness levels.
 
The Pool and Spa Informational Website
askalanaquestion.com

Calcium Hardness Pool Chemistry
Calcium Scale Pool Problems

 

 
 

Scroll down to browse through some archived SWIMMING POOL questions and answers.  Please click the Pool Topics Link, on top of every page, to access a complete listing of Pool Problem subjects, an alphabetized Website Table of Contents, Pool Equipment Information, About Alan Biographic Material and a Pool Glossary. Use the other links to access additional subject information. More information about some new and unique products, for pools and spas, can be found by visiting The Website Store. You'll never know what you'll find and that's always fun. Be better prepared and avoid costly problems!

 
One of the ColorQ all-digital, pool and spa water analyzers. The Magnetizer for pools and spas. The Circulator for all types of pools.
METALTRAP Filters remove iron, copper and manganese. Model SR salt chlorine generator, for all types of pools.
Remote Controlled Pool Surface Skimmer. Magnetic Water Conditioners, for Pools, Spas, or the Whole House, help deal with the consequences of high levels of calcium hardness. Magnetic Conditioners help reduce the cause of scaling and promote better water quality. Scale reduction helps improve heater and filter performance. Floating Pool Skimmer.

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How to manage calcium hardness levels in pools? Calcium is a naturally occurring mineral that is frequently found in high concentrations: such water is called "hard" water. Calcium hardness chemistry is one of the important pool water parameters and its control is important, to help assure proper water quality and help avoid certain pool water problems. The preferred ranges, in swimming pools, are 80-150 PPM in a vinyl pool and 150-200 PPM in a masonry finish pool. Low levels of pool water calcium hardness (soft water) can lead to the problems of corrosive water conditions. Chemicals are available to raise the calcium hardness, as might be necessary. High pool water calcium hardness levels, especially above 400 PPM, can lead to possible pool water clarity problems and scaling conditions. Chlorine products containing calcium hypochlorite raise the hardness level, each time the product is added. Discontinuing such product usage can help avoid further unwanted increases in the calcium hardness. Various chelating or sequestering Mineral Treating Products are available to help deal with the problems associated with high calcium hardness levels. Pool water calcium levels can be determined by a simple water analysis. This is especially important with well water, as other problematic minerals might be present and could require treatment. Pool Water Magnetizers, also called Magnetic Water Conditioners, have been reported to help reduce and eliminate scale formation, by inducing a positive electrical charge in the water passing through the return lines.  If problems arise, refer to the Pool Problems Page, as a source of problem-solving information, broken down into various categories.  Scroll down the page and click on the linked keywords, catch phrases or images, in the archived answers below, to access additional information, on that topic or product.

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Pool Scale Deposits?

I've noticed a white hard deposit along the water line on the tiles. Our guess is that it may be calcium deposits. If that's the case, what would be an appropriate way to get rid of the deposits and to prevent it from happening again? In one of your answers we read your suggestion about using Mineral Treatment and lowering the overall pH (to 7.2 or so). Would this be advisable to do in our case as well? Are there any specific recommended brands for the Mineral Treatment and how do you use it? Thanks!

Juan C., 4/12/2016


Most likely the deposits are calcium scale. This pool problem is most likely due to the water reaching the saturation
Liquid MetalTrap point, so far as calcium hardness is concerned. These deposits can removed using a strong muriatic acid solution. Apply with a sponge and make sure to wear rubber gloves and eye protection. First, test in a small area to see how it will affect the deposits and the tile. If your calcium hardness level is above 400 PPM, you will have to add a quality, phosphate-free mineral treatment, such as Liquid MetalTrap - possibly several times the suggested dose - in order to try and avoid a recurrence. Your local pool professional should be able to suggest a product. Keeping the pH closer to 7.2 and the total alkalinity closer will, also, help reducing the scaling tendencies of the pool water. For more information on the topic, refer to the "Langelier Index" page. The addition of a Magnetic Water Conditioner might be able to help resolve some of the scaling issues.

If this website was helpful, in answering your question, please consider joining our E-Letter Mailing List.  You'll receive 1-2 E-Letters a month, with helpful information, new product updates, suggestions and sale announcements. I hope that this recommendation works out for you.

Sincerely. Alan Schuster, 4/12/2016
 

Ryznar Stability Index?

What is the Ryznar Stability Index and how does it help protect heaters and other equipment, from corrosion?

Austin S., 8/15/2013


An article appeared in the 8/12/11 issue of Pool and Spa News about the Ryznar Stability Index. This index is favored, by some heater and equipment manufacturers, because it affords greater protection against corrosion, than does the more familiar Langelier Index. It favors higher calcium hardness levels and/or higher pH levels. While this will lessen the possible the corrosive effects of softer, lower pH water, it comes at a price. It boosts the calcium hardness to a point, where scale begins to form, which actually helps protect the equipment, from corrosion. However, as scale forms in the heater, it reduces the efficiency, by acting as an insulator. In a filter, it acts to cement the filter media, reducing the effectiveness of the filter.  In areas of the southwest, the water is already too hard, right out of the tap and it is challenging to main a clear pool, without excessive scaling. For more information, go to this website page: Ryznar Stability Index I hope that this information will help you better protect your pool equipment.

Sincerely. Alan Schuster 8/19/2013


Scale Deposits In A Pool Heater?

I read somewhere that very high pool water calcium hardness and pH can lead to scale formation and that scale can form on the underwater surfaces, including in the heater. My water has over 500 PPM of calcium hardness. I have a solar heater. I don't see any real evidence of scale. Every once in a while, I get cloudy water. Is there something I can do to avoid a potential problem? Please help.

J.M., 7/22/2011


A calcium hardness level of 500 PPM can definitely lead to scale formation and it can take place in your solar heater or any
WaterLink SpinTouch Tester, for pools and spas. other type for that matter.  If so, it will reduce the heater efficiency, by acting as a layer of insulation. Make sure that you keep the pH closer to 7.2, than to 7.6. Try and lower the total alkalinity to within 80-120 PPM, if practical. Stop all use of products containing calcium.  Add a quality Mineral Treatment, in order to help sequester the calcium, on a regular basis. This treatment can actually slowly dissolve calcium scale deposits, over a period of time. There's nothing in your letter that positively indicates that you have a problem, at this time. But, some prevention does make sense. To confirm the overall pool water chemistry, visit a pool store that has a very reliable, professional lab such as a WaterLink SpinTouch Lab, as opposed to  a less accurate test kit or strip reader.  To find a dealer near you, go to: LaMotte Professional Testing Center Locator.  I hope that I have been helpful.

Sincerely. Alan Schuster, 7/23/2011


Low Hardness And Leaching?

We were told if the pool calcium level was too low it would cause a leaching problem. Is this correct and what is leaching?

Cindy J., 6/20/2010


At the optimum ranges for pH and total alkalinity and at a given water temperature, the pool water can keep in solution, without a problem, up to approximately 200-400 PPM of calcium hardness. If the water is soft (low hardness) the pool water will dissolve enough calcium minerals from the walls of masonry pools to raise the calcium hardness into this range. This process is called leaching. In the course of this happening, over time, it can be difficult to maintain the pH and total alkalinity. For this reason, it is advisable to raise the hardness to approximately 200 PPM, by adding sufficient calcium hardness increaser. I hope that this information will prove helpful. Enjoy the summer.

Sincerely. Alan Schuster, 6/20/2010


Unsure About Test Colors?

I use a drop type test for calcium hardness and total alkalinity and am left feeling unsure about what the test results should be. The colors don't seem to match up properly. Any suggestions?

David F., Mesa, AZ 5/2/2007

One of the ColorQ all-digital, pool and spa water analyzers.
Some people have difficulty seeing slight differences in colors and that could be part of the problem. In addition, the testing
chemicals may in need of replacement or may not be the right ones for your tester. While these tests are not as crucial as pH or chlorine, you still want reliable results. The TA should be about 80-150 PPM. The calcium level for a vinyl pool should be about 80-200 PPM and about 150-250 PPM for a masonry pool. To achieve more reliable test results and eliminate all color matching, you might consider using the all-digital ColorQ PRO 7 Water Analyzer. It does 7 of the common, most important pool tests and is ideal for people with color vision difficulties. I hope that this information will prove useful.

Sincerely. Alan Schuster, 5/3/2007


Hardness and Magnetic Water Conditioners?

Magnetic water conditioning sound like a good idea. I've read that one of the benefits is that they may eliminate hard water problems, but is it possible that they will make the water too soft I've got a plaster pool with hardness of 160, TA of 155, pH 7.4. I don't want hardness to drop and would like to know if a magnetic water conditioner will lower the hardness. Many Thanks,

Cheryl, Springfield, VA, 5/31/2010
Magnetic water conditioner for pools and spas.

The Magnetizer Water Conditioner will not lower your hardness level or create issues dealing with etching or corrosion of the plaster. It uses magnetic
energy to allow the calcium to avoid forming scale deposits and helps make overall water chemistry easier. Your pool water is will probably increase in hardness, as times go by and the Magnetizer will help prevent future problems. It is simple to install and requires no energy or power source. I hope that this information proves helpful.
 
Sincerely. Alan Schuster, 5/31/2010


Erratic Scaling?

We have a new pool that has what looks like scale deposits. The automatic cleaner looks like a glazed donut, the filter for the pool is as hard as a rock. Is there any specific reason for this? Sincerely.

Jacqui, Florida, 2/2/2005


Three factors contribute to scaling conditions: high calcium hardness (usually over 400 PPM), high pH (usually over 7.8) and total alkalinity (usually over 200 PPM).   All three together can make it even worse. You can lower the pH and TA with acid. The calcium hardness might be controlled, but not necessarily lowered, by adding a calcium sequestering agent. I suggest that you test the water for pH, TA and calcium hardness. The Langelier Index will tell you if the water is scale forming and help indicate how improve the situation. Needless to say, avoid using products that contain calcium. I how that I have been helpful.

Sincerely. Alan Schuster, 2/2/2005


Magnetic Water Conditioner For Scale?

We live in AZ with well water and are constantly battling our pH levels and dealing with scale buildup. I'm interested in purchasing The Magnetizer, but there are no specifications on the diameter pipe it will fit. I've got a 2" return line.
Magnetic water conditioners for spas, pools and the whole house.
Cale C., Arizona, 4/10/2007


The Magnetic Water Conditioner simply clamps around the pipes and should accommodate all of the pipes used in residential pools and spa. I
apologize that that was not pointed out on the website.  It will be added to that page.  I hope that I have been helpful. If so, please tell your friends and dealers about the website.

Sincerely. Alan Schuster, 4/11/2007


More Scale Deposits?

Alan, I researched your site and could not find an answer to my problem.  I have an above ground 24' pool.  We live in Myrtle Beach, SC.  The pool is about 4 years old and this is the first time this problem has arose.  The pool is completely shut down and shut off every fall.  While preparing to open the pool for this season I noticed scale on the walls of the liner.  I did not try to balance the water because I know the scale will not come off if the pH is normal.  At this time the pool water tests corrosive.  Water condition is cloudy with some blue green algae.  My problem is the scaling, I have brushed and brushed, but it doesn't seem to be helping.  Any other products or solutions to address this? Thanks.

Scott, Myrtle Beach, SC, 4/18/2010


It does seem likely that you are experiencing calcium scale deposits. However, without specific pool water analysis data, I will have to make assumptions and generalizations. Scale deposits can occur, if the calcium hardness level is over 400 PPM and are
Magnetic water conditioner help solve scaling and hardness problems. even more likely if the pH and total alkalinity are above ideal. It would be useful to know the calcium hardness of the pool and source water at this time! To remove the scale, lowering the pH to approximately 6.0 will help dissolve the deposits. The addition of a quality mineral treatment will also help to descale the surface. Try and find a product that is recommended for the control of calcium and scale. Use the pool brush to help things along. It may take a few days to dissolve the deposits, depending upon the nature of the deposits and how low the pH is maintained. After the deposits are removed, raise the pH and TA. In order to avoid cloudy water and scaling, try and keep the pH closer to 7.2 and the TA below 120 PPM. Shocking will help control the algae that is present - in fact, the lowering of the pH should help in that regard. If you are using any products that contain calcium, I suggest that you discontinue their use. A newer way to help control scale, in a pool, spa or entire house, is with a  Magnetic Water Conditioner. It uses magnetic energy to condition the water, as it passes through the return line.  I hope that I have been helpful.

Sincerely. Alan Schuster, 4/18/2010


Hard Water Sanitizer Choice?

I'm writing from the UK. For an in-ground tiled pool with very hard water, which is better, a chlorinator or a brominator?

Kevin R., UK, 1/28/2005
NUVO Ultraviolet Sterizers for Residential Pools.
I assume that you are not referring to salt chlorination? Otherwise what follows is not applicable. Given the fact that you are dealing with very hard
water, I would try and use a system that allows for reduced chemical usage. Bromine cannot be stabilized to protect it from the Sun's UV light. Chlorine can! I would use chlorine and try to use as much liquid chlorine, as possible, to supplement the chlorine tablets being added with the chlorinator. You might consider adding an Ultraviolet Sterilizer, as it contributes no build up products and will greatly reduce the amount of chlorine required. You can better explore your chemistry options with the Langelier Index. I hope that I have been helpful.

Sincerely. Alan Schuster, 1/28/2005

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Getting Ready For Winter?

I live in Central Illinois and have an inground pool. It is concrete with a vinyl liner. I will have to close it for the winter in mid-October. My calcium hardness is very high. It is currently 380. Although, based on information I found on your website, I watch the Langelier Index very closely and make sure it stays in the -0.5 to +0.5 range. My question is, should I attempt to get the hardness level down to a more acceptable range before closing the pool for 6 - 7 months? As a new pool owner (only had it 1 year), I truly appreciate your website and have learned a ton from it. I also got tired of the simple color water tester and purchased a ColorQ PRO 7 digital water tester from your site. Best money I've spent this summer! Thanks!

Jeff M., Illinois, 9/5/2008


Glad to hear that the ColorQ PRO 7 is serving you well. A hardness level of 380 is manageable, so long as the pH is under 7.6. Lowering the level might give you a greater margin for error. Much will depend on the hardness of the replacement water. You will remove some water for the winter and that will help next spring, no matter what. I would get the pH to 7.2-7.6 and close it up. Thanks for your purchase of the ColorQ PRO 7 Water Analyzer and I hope that this information is helpful.

Sincerely. Alan Schuster, 9/6/2008


Should I Raise The Hardness?

I live in the western suburbs of Sydney. I have an above ground pool, 35000 litres recently installed, 2 months old. Using sand filter/chlorine. The pH is 7.8. Total Alkalinity is 180. Total chlorine 1 & Free Chlorine 1. Total Hardness is 80. I did a test on the tap water used to fill the pool and the Total Hardness was 50. From my calculations I need to add 4 kg of Calcium Chloride to increase the calcium hardness. Given that the local water is low in calcium will this need to be adjusted regularly. How important is calcium hardness? Thanks.

Scott W., NSW, Australia, 4/24/2009


Inasmuch as you have a vinyl lined pool, I would opt not to increase the calcium hardness, above the current level of 80 PPM. If the pool was masonry, I would have suggested that it be raised to 150-200 PPM. A level of 80 PPM is the recommended minimum for vinyl lined pools. Given the high TA and pH, you are better off with the lower value. Adding new water will lower the level slightly. Adding calcium hypochlorite chlorine products will raise it slightly. I hope that I have been helpful.

Sincerely. Alan Schuster, 4/24/2009


Hardness Booster In A Vinyl Pool?

Just purchased a new liner for my pool. My installer says calcium chloride (calcium hardness booster) isn't necessary in vinyl pools. The people who sell me chemicals for my pool suggest it is? What say you? Given: all the other numbers, pH, stabilizer, etc are good. Thank you in advance.

Michael J., Havana, FL, 5/13/2005


I say you don't raise the calcium hardness and with the money saved, you take the wife out to dinner. Being that you live in Florida, it is safe to assume that your water is not soft.  The suggested range for calcium hardness in vinyl pools is 80-200 PPM and there is no need to go above 80 PPM. As long as you keep the chemistry right, there should be no problem. A gunite pool would have been a different matter. Enjoy the pool.

Sincerely. Alan Schuster, 5/13/2005

How to deal with high Calcium Hardness problems.

Use a Pre-Filter to avoid adding mineral sediments, when adding new water.
Use a salt Chlorine Generator for better sanitizer control and fewer byproducts.
Add The Magnetizer, to help maintain existing hardness and reduce scale formation.
Robotic Pool Cleaners offer better vacuuming performance and hard water benefits.
Better control of the  water chemistry helps minimize and avoid scaling problems.
MetalTrap 1-Micron Pre-Filters, for Pools and Spas. Model SR salt chlorine generator, for all types of pools. Magnetic water conditioners for spas, pools and the whole house. Robotic Pool Cleaner ColorQ all-digital water analyzer.
Using a Pre-Filter, when adding new water, removing mineral sediments. A salt chlorine generator offers more control and less chlorine odor. The Magnetic Field alters the state of dissolved calcium, reducing scaling. Better vacuuming removes mineral sediments, and reduces buildup. Maintain proper water chemistry, for effectiveness and bather comfort.
Click on any image for complete product and ordering information.

Using A Water Softener?

Alan. Great website! Thanks! I'm in Tucson and constantly fighting high hardness in my in-ground pool. To combat it, could I add a water softener to the auto-fill line for the pool?

B. R., Tucson, AZ, 8/30/2008
Magnetic water conditioners for spas, pools and the whole house.

Absolutely!!! You want the hardness under 400 PPM. 200-250 PPM would be ideal. Test the cyanuric acid level, as well. If it is high, you could simply
pump out some water and replace it with softened water. You could recirculate the water, until it is under 400 PPM. Or you could hook it up, as you planned. While nothing is better than lowering the hardness to a manageable level, The Magnetizer Water Conditioner is a device that can help reduce scaling problems.  I hope that this information proves helpful.

Sincerely. Alan Schuster, 8/30/2008


Disappearing Calcium?

I have a city pool that's 300,000 gallons and uses gas chlorine. Its a concrete painted pool with sand filters. The problem I have is that no matter how much calcium I use, I can't keep 200 ppm in the pool. I can get it there, but in a day it starts going back down. I'm using calcium chloride like it going out of style. Help.

Dave R., 1/28/2006


The only way that calcium can leave the water is by precipitation and that would create an obvious cloudy water condition. If there is no cloudy water problem, I see only three possibilities: the calcium chloride is actually something else, the test equipment is not working properly or is being interfered with by something in the water (a chelate for example) or there is a significant water leak. Of the three, a water leak seems most likely, especially, if the source water is soft. The gas chlorine and or the painted surface should play no role in the problem. I hope that I have been helpful.

Sincerely. Alan Schuster, 1/28/2006


Calcium Nodules?

I recently had my pool replastered with a blue color about 3 months ago. There are approx. 20 little white spots at the bottom of the pool that will not come up with brushing. I first noticed this problem when there were about 5 of them. The company that did the replaster job said to keep brushing. I have been told that the spots are calcium nodules. How do I get rid of them? Thanks.

Terry, 4/17/2004


I wouldn't do anything without checking with the contractor. My suggestion would be to add a dose or two of a calcium sequestering treatment. In addition, I would try adding 1/2 pound of pH reducer in a white sock. Drop onto a spotted area and slowly move around with a wooden pole. Hopefully, this will dissolve the calcium deposits, if that is what they are. Check the pH, TA and calcium hardness and adjust, as necessary. Again, first check with the contractor, inasmuch as the finish is only 3 months old. Also, it is possible that the nodules are being caused by delaminations (separation of the old and new finishes), voids or hairline cracks in the finish. This can lead to eruptions or nodules being formed on the surface. It does happen more frequently in refinished pools and should eventually stop. It may be necessary to sand down the nodules, to restore the appearance. Discuss this with the contractor. Good luck.

Sincerely. Alan Schuster, 4/17/2004


Hard, White Deposits?

Hi Alan, I found your website to be very informative, thanks for your efforts. I have an in-ground concrete pool with plaster walls and I recently drained it for the first time after four years to replace some cracked tile.  I noticed some algae growth underneath the drain cover in the spa and decided to remove the drain cover to clean it. What I discovered shocked me. Underneath the green/black algae growth was a thick layer of white, rock-hard mineral deposits. I then uncovered the pool drains and they had the same white, hard deposits with hardly any algae. The accumulation is hard as a rock, and very difficult to remove.  Is this normal? I'd hate to think how much more may accumulate after another four years. Can you recommend a method to loosen the deposits and clean this off? Is there a way to prevent this from happening? Thanks for any information you can offer.

Sergio G., El Paso, TX, 11/19/2007


There is no reason to believe that these calcium scale deposits (that is what they seem to be) are not also present in the pipes and in the filter. The cause of the problem is most likely due to high levels of calcium hardness and possibly high pH and TA. Upon refilling the pool, test for calcium hardness and do not add any calcium hardness booster, except enough, if necessary, to raise to raise the level to 150 PPM. Avoid all use of calcium hypochlorite products. Once a month add a dose of a calcium sequestering product. Keep the pH at 7.2-7.6 and the TA at or close to 80-120 PPM. This could create conditions that can slowly dissolve the deposits over time or at the very least help prevent a worsening of the problem. The addition of a Magnetic Water Conditioner might be able to help resolve some of these scaling issues. I hope that this information proves to be helpful.

Sincerely. Alan Schuster, 11/19/2007


What Is A Water Magnetizer?

I have a pool that is located in a hard water area and as a result I have some scaling problems. The pool service guy has mentioned something called a magnetizer. Can you add something more?

Ted, Tucson, AZ, 4/25/2008

Magnetic water conditioners for spas, pools and the whole house.
Pool magnetizers or magnetic water conditioners are strong permanent magnets that are strapped on the return lines. It is reported
that pool water passing through the return lines is subjected to a magnetic field, causing micro-changes in some of the water content, as a result of an induced positive electrical ionic charge. In short, the magnets are said to cause some beneficial changes: reduction and elimination of calcium scale, improvement in sanitizer efficiency and some positive effects on the overall water chemistry. In hard water situations, this type of product can make a substantial improve in the water quality. No power is required and installation should be a simple. I hope that I have been of assistance.

Sincerely. Alan Schuster, 4/25/2008


White Deposits?

We have a chlorine free pool. What can we use to remove the white deposit. Lime? Also, could tell me where I can get test kit: LaMotte COPPER test kit model EC-70 code 3619. Thank you.

No name, Hawaii, 5/7/2008


You should be able to remove the deposits, from limited areas, with an acidic solution. The deposits are not lime
(calcium oCopper test kit for pools and spasxide). Most likely the problem is due to calcium carbonate scale deposits. Try equal parts of muriatic acid and water: add the acid to the water and wear eye protection and rubber gloves. If the entire is scaled over, you probably will have to drop the pH to approximately 6 and keep it there for a while. Use the brush to help loosen the deposits. In addition, you should deal with the underlying causes. Make sure that the pH is not above 7.6 and is closer to 7.2. Keep the total alkalinity below 120 PPM, if possible. Something tells me that your "chlorine Free" has an Ionizer. If that is the case, the use of mineral and scale treatments could interfere with the copper ions. Use them only as recommended by the equipment manufacturer. Copper Test Kits are available in our test equipment store.  the choice includes ColorQ Test labs, individual testers and Test Strips. I hope that I have been of assistance.

Sincerely. Alan Schuster, 5/8/2008


Scaling And Green?

My 24 ft above ground vinyl lined pool has a layer of scale on the sides and is green as no chemicals were kept in the pool over the winter. We've never had problems before with scale. The pH is over 8.4 and the total alkalinity is high. What do I need to tackle first the scale or the algae or do I need to adjust the pH first? Help! I really need to get this layer of crud off my walls. Besides scratching it off with my fingernails what will dissolve it? Thanks.

Bob F., Clearwater, FL, 3/29/2005


It is not positively apparent that you have calcium scale deposits. It is a possibility, given the fact that high pH and total alkalinity tend to promote scaling in the presence of high calcium hardness. There is no question that you have an algae problem. Start by lowering the pH to about 7.0, as this will help dissolve scale and make the Free Chlorine more effective. Boost the Free Chlorine level to 5-10 PPM and keep it elevated, until the algae is gone and the water clears. Have the water tested for calcium hardness. If it is over 400 PPM, scaling is a distinct possibility and a calcium scale treatment should be added. Once the water and walls improve, adjust the pool water chemistry to optimize conditions. I hope that this information will prove helpful.

Sincerely. Alan Schuster, 3/29/2005


What's Floating In My Pools?

I am a service tech in Northern Nevada. I have two pools that have a white flaky substance floating in the water. I cannot identify this substance. I have called the health department and a local representative for a major chemical company. They don't know what it is, either. The condition of the pools are as follows: Indoor, bromine as a sanitizer, heated to 82 degrees, solar cover, usage is minimal, sand filters, minimal fluctuation in chemical balance, one pool is painted and the other is plastered. At first it looked like calcium deposits floating around. I checked total hardness of the water and both are within respectable parameters. There is no slime on the pool walls. No algae growth anywhere. The sand was changed about two months ago in one pool and should be changed in the other. I hope you can help me with this problem. If you need more information, please don't hesitate to ask. Sincerely.

T.B., Nevada, 1/23/2007


From your description it does sound like calcium scale deposits. Your stated that the calcium is "reasonable." However, Nevada is not known for soft water. What is reasonable in your state would be considered very hard water in other areas of the country. It is my suggestion that you proceed on the basis of a calcium problem because the problem seems to point no where else. It is not uncommon for spas to get white floaters, caused by calcium deposits "flaking off" the underwater surfaces of the heater and circulation system. This seems to be the same problem, but in a pool. Even though the water chemistry might be perfectly acceptable today, if is possible that, at sometime in the past, the calcium hardness was higher or that the pH and/or total alkalinity were too high. High pH and TA can lead to scale formation in hard water. On this basis, I suggest that you add a double dose of a quality, phosphate-free, Mineral Treatment, such as Liquid METALTRAP. These products should act as descaling agents and help remove the deposits over time. It is possible that the problem will appear worse for a short time, due to the accelerated "flaking off." Afterwards, things should return to normal. If this is, indeed, the cause of the problem, there should be an improvement in both the filter and heater efficiencies. The fact that the sand in one pool was recently changed, does not necessarily help, because sand filters are more efficient after being used for a while. The other one might have scale deposits in the sand bed. I hope that this information will prove helpful. Good luck.

Sincerely. Alan Schuster, 1/23/2007


Pool Water Turning Milky?

I am from Columbus, OH and work for a swimming pool company. I feel fairly knowledgeable having been in the
ColorQ all-digital water analyzers, for pools and spas. industry for nearly 10 years. Recently I have had a recurring problem that I cannot solve or find the cause of to treat. When I add soda ash to specific pools they cloud up, not hazy but a complete cloud, almost like a bowl of milk and the only thing that will clear it up is a floc treatment or a poolside portable D.E. filter. This only happens in certain pools, not all of them. The only pattern I have noticed is that all the pools that this happens to either have well water, old galvanized walls or poor water treatment facilities because they are out in the country a little more. I would assume that this problem is being caused by the presence of minerals or metals, but I have found nothing out of the ordinary when doing a iron or copper test. Do you have any idea what could be the cause and the proper treatment to eliminate recurrence? Thank you.

Todd H., Columbus, OH, 6/23/2005


While there may be traces of iron and copper in the water, that is not the problem. These metals would produce discoloration and not just cloudy, milky-looking water. The addition of the soda ash raised both the pH and TA. This, in turn, lowered the solubility of calcium and other minerals and lead to the cloudy water. Most likely these polls have high calcium hardness levels, as well as possible high level of magnesium and high TDS. You should try and keep the pH closer to 7.2-7.4. Calcium treatment can be added on a regular basis and all use of calcium hypochlorite should stop. When adding soda ash, add it very slowly and distribute it around the pool perimeter. If you refer to the page on the Langelier Index, you will gain insight to the relationship between pH, TA and calcium. I hope that this information helps solve the problem.

Sincerely. Alan Schuster, 6/23/2005


Calcium And Total Hardness?

My total hardness reads 500 on strip test and my calcium hardness reads 170. What else besides calcium is total hardness comprised of? Thanks.

Steve S., 2/21/2005


Total Hardness is comprised of calcium and magnesium hardness. That's why the TH reading is usually higher. If some areas magnesium can be present in the water supply. It is much less of a problem, than is calcium hardness. Just try and keep the pH and TA under control and avoid using products such as calcium hypochlorite. I hope that the information proves helpful.

Sincerely. Alan Schuster, 2/21/2005


False Test Reading?

Do you have any idea what could be giving a false reading of zero calcium in my pool. The pH is ideal and chlorine is adequate. I have a 25,000 gal pool and have actually added 30 lbs of calcium over the last several days and yet the calcium reading still indicates zero (tested by my pool man, as well as a pool store). Thank you for any response. Regards.

Randy B., 9/6/2009

ColorQ all-digital water analyzers, for pools and spas.
There is no ready explanation. Two locations doing the testing makes it difficult to suggest testing errors, but that is still
possible. The only other alternative is that something present in the pool water is interfering with the tests. Have the water tested for copper, as it is the number one interference in hardness testing. In some cases, it drags out the end-point color change giving high results and in other colorimetric tests, in can produce low results.  Bring in a sample of your tap water and see what kind of readings they get. In any event, I would assume that the calcium level is close to ideal, at the very least. A better water tester might prove useful and be a money saver too. The ColorQ digital water analyzers eliminate the color-matching and guesswork. I hope that I have been helpful.

Sincerely. Alan Schuster, 9/7/2009


Langelier or Saturation Index?

I have been reading through some material that was been given to me by the pool dealer. It refers to the Langelier Index. Could you explain?

Bob M., Oregon, OH, 2/11/2004


The Langelier or Saturation Index is a calculation that measures the s corrosiveness or scale-forming tendencies of swimming pool or spa water. Using data such as pH, total alkalinity, calcium hardness and water temperature, a value is calculated. A result of -0.5 to +0.5 is considered ideal. Lower values are corrosive and higher values are scale-forming. The Langelier Index helps indicate the extent of the water chemistry correction, needed to create ideal water conditions. I hope that I have explained the concept and its use.

Sincerely. Alan Schuster, 2/11/2004


Treating Pool Calcium Hardness?

Hi Alan, I have read that you recommend a quality mineral treatment for high calcium levels - what is a mineral treatment?

Vicki H., Dunedin, New Zealand, 3/17/2007


Mineral Treatments are chelating or sequestering agents. They are used to help avoid staining or discoloration due to trace metals or to avoid the scaling and cloudy water conditions, that are associated with high levels of calcium hardness. You didn't supply any details, so I'll have to speak in generalities. If the calcium hardness is over 200 PPM and below 400 PPM, it is above the ideal, but it is manageable. Avoid the use of products containing calcium, keep the pH at 7.2-7.6 and try to keep the total alkalinity in the 80-120 PPM range. If the calcium hardness is above 400 PPM, the use of a mineral treatment is advised, in order to avoid possible problems. It is, also, important to keep the pH and TA nearer the low end of optimum. A reliable water tester might be just what you need. The ColorQ digital water analyzers eliminate the color-matching and guesswork. I hope that I have been helpful.

Sincerely. Alan Schuster, 3/17/2007

Hi Alan, thanks for your prompt reply - we use Calcium Hypochlorite in the pool and at the moment our calcium hardness level is 310
.
Vicki H., Dunedin, New Zealand, 3/17/2007


A level of 310 is not a serious problem. However, if you continue to use the calcium hypochlorite the level will continue to rise and will eventually become a problem. I suggest that you switch to a stabilized form of chlorine. Use the existing stock of calcium hypochlorite as a shock treatment, until the supply is exhausted. High calcium levels will lead to cloudy water and scale deposits on the underwater surfaces, so it is not too late to get a handle on the water chemistry. I hope that I've been helpful.

Sincerely. Alan Schuster, 3/17/2007


Lowering High Calcium Hardness?

We have been told the effective way to reduce calcium is to drain the water. I hate wasting water and would like to know, if there is any other way (chemically or mechanically) to do it. My pool calcium is around 450 after I drained 1/3 of the 25,000 gallons water. Thanks.

W. K., 4/9/2005


Replacing water will work, especially if the new water is much softer. That would mean that the high calcium hardness probably resulted from the prolonged use of calcium hypochlorite products. 450 PPM is about the upper limit, that can be controlled conveniently. Just keep the pH close to 7.2 and there should few problems. Of course, stop using any form of calcium hypochlorite. Adding some calcium sequestering products can improve the safety margin, by helping to avoid scaling and clouding of the water. Good luck and I hope that I have been helpful.

Sincerely. Alan Schuster, 4/9/2005


Too Much Calcium?

When I opened the pool this spring I brought in a water sample for analysis. It was pretty good, except for the calcium, which was 440 PPM. It is a vinyl, inground pool, about 20,000 gallons. My household water is not high in calcium, I had that tested too. I have been using granular calcium hypochlorite for the past few years. I guess that is where all the calcium came from. I did have a few cloudy water problems last year. The sand in my filter didn't look right, so to be on the safe side, I changed it. My question is, what should I do about the high calcium and can it cause a problem? Thanks.

Lou R., Middletown, NY, 6/7/2006


It is quite likely that the high level of calcium hardness could have caused the cloudy water and may have caused the filter sand granules to cement together. High pH and high total alkalinity can add to and worsen the problem of high calcium hardness. I suggest that you add a regular dose of a quality calcium scale, to help deal with the calcium problem. To help keep the calcium in the water from precipitating or scaling, I suggest that you keep the pH closer to 7.2 and the TA closer to 80 PPM. Doing this will help keep more calcium in the water and reduce the possibility of negative effects.  In addition, I would suggest that you stop using the calcium hypochlorite, for daily sanitizing. Continued use will cause a further increase in the calcium level and can lead to more and more problems. A switch to a stabilized chlorine, for example, will not add more calcium. Eventually, due to backwashing and winterizing, the calcium level will decline over the years. Test for calcium, periodically to track of the progress. Any calcium hypochlorite, left on hand, probably could be used for shocking purposes only. Thereafter, try and avoid or limit the use of products containing calcium. I hope that this information will prove helpful.

Sincerely. Alan Schuster, 6/7/2006


Too Little Calcium?

I just had a gunite pool put in and I brought a sample of water in for testing. I was prepared for a long list of chemicals, but I was surprised by the amount of calcium increaser that was recommended. Almost 40 pounds! It's a big pool and the water is soft. Does this make sense to you?

Dick S., Ramsey, NJ 8/23/2011


Does it make sense? Even though you didn't provide much in the way of details, it does make sense. You want the calcium hardness level at 150-200 PPM. If your water is soft and the pool big, 40 pounds sounds quite reasonable.  If you don't raise the calcium hardness level, it will be more difficult to maintain the pH. The reason being, if you don't add the calcium to the water - the water will dissolve or etch the walls, until an equilibrium is reached.  If you want to avoid the pH problems and the surface etching, you should add the calcium hardness increaser. Fortunately, the chemical is not overly expensive and it should be a one-shot expense. The dealer is really doing the right thing, with the recommendation. I hope that I have been helpful.

Sincerely. Alan Schuster, 8/23/2011


Way Too Much Calcium?

My water supply comes from a well and it is very hard. As a result of this, the calcium hardness of the pool water is about 800 PPM. I've had cloudy water, scaling and a rough deposit on the tile surfaces. Short of having softer water trucked in (which I would like to avoid), is there anything I can do? Looking for some help. Thanks.

Carl R., Sedona, AZ, 3/23/2008


I agree, a calcium hardness reading of 800 PPM is too high and problems are not unexpected. Trucking in water or having some of the water softened are obvious solutions, that you just might have to consider. In the meanwhile, I suggest that you try the following steps. Add a double or triple dose of a quality Mineral Treatment to help sequester the calcium. Drop the pH to 7.2 and try and keep it there. The lower pH will help keep more of the calcium in solution and could help solve or reduce the problem. Your total alkalinity is also probably too high. You may not be able to do much with the TA, because it is probably not due solely to carbonates. Lowering the pH will lower the TA, so you should expect to see some improvement. Under no circumstances should you use products containing calcium. Read the labels. There are chlorine and shock treatments that do not contain calcium. The key to success may be the lowering of the pH to 7.2 and keeping it there. For more information on the calcium scale, refer to the "Langelier Index" page. I hope that this information will prove helpful.

Sincerely. Alan Schuster, 3/24/2008


Rough Deposits?

We have a salt water pool. We live just north of Dallas. It seems as though the salt is sticking to the sides of the walls in the pool. Is this possible? How can we fix this? A brief history on the pool. Our pool was built this year (2004) and was finished at the end of Aug. About a month ago, we had scale build up. We fixed that problem with acid. Then, within the last week, we've had an algae breakout. We've been working on fixing this problem. Got the chemicals where they need to be; just need to shock the pool. When I was brushing down the walls with an exfoliating glove on my hand, I noticed how rough all the walls were. It seems to be salt build-up. Any help you can provide is greatly appreciated!

Dachia G., Texas, 11/22/2012


Salt shouldn't form underwater deposits like you are describing. Most likely it is calcium scale. The factors that lead to this problem include: high pH, high TA and high calcium hardness. Try lowering the pH and TA to something closer to 7.2-7.6 and 100 PPM. Adding a calcium treatment can help remove the deposits, over time, and help keep the salt chlorinator plates clean. I hope that the information proves helpful.

Sincerely. Alan Schuster, 11/22/2012


High Calcium And TDS?

We just bought a house with a 20,000 gal. swimming pool. As it is the first time, we are uncertain how to treat the water. The test results are: FAC 8, TAC 8, pH 7.3, total alkalinity 230, CYA 100, calcium hardness 870, TDS 2600, negative on copper and iron. I would appreciate if you could give me some advise on how to start treatment. Thank you.

Walter W., Temecula, CA, 8/30/2010


A calcium hardness reading of 870 PPM is very high. I suggest that you add a dose of a quality Calcium Treatment on a monthly basis.
Professional Sat Water Test Kit. In addition, try and keep the pH at 7.2-7.4 and the TA below 200 PPM. Doing this can make the water chemistry more tolerant of the high calcium level. Free and Total Chlorine readings of 8 are doubtful. It would be unusual for both readings to be the same. In any event, it is indicative of too much chlorine for proper bather comfort. Try and keep the Free Chlorine reading at 1-3 PPM. The Total Chlorine reading should be no more that 1 PPM higher than the Free Chlorine. The Total Dissolved Solids (TDS) test results can be the real problem. You didn't include your state, but I suspect that it is in the southwest. A TDS of 2600 PPM is very high and can lead to water quality problems and the loss of sanitizer efficiency.  It would be a good idea to have your household water tested. If it is much lower, you should consider doing some water replacement over time. Good luck.

Sincerely. Alan Schuster, 8/30/2010

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