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Minerals-Metals-Discoloration Problems

Spa or hot tub scale and discoloration treatments.
The Pool and Spa Informational Website

Treating Spa or Hot Tub Scaling and Water Discoloration.


Scroll down to browse through some archived SPA and Hot Tub questions and answers.  Please click the Spa Topics Link, on top of every page, to access a complete listing of Spa and Hot Tub Problem subjects, an alphabetized Website Table of Contents, Spa and Hot Tub Equipment Information, About Alan Biographic Material and a Spa and Hot Tub Glossary. Use the other links to access additional subject information. More information about some new and unique products, for Spas and Hot Tubs, 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!

METALTRAP Filters remove iron, copper and manganese. #2056 ColorQ PRO 7, all-digital pool and spa tester. MetalTrap Stain Reversal Kit, for pools and spas.
MetalTrap Dual-Cartridge Filter, for pools and spas. TotalTrap Pool Refresh removes phosphates and heavy metals
Ultra Poly One Coat - before and after pictures. The proper treatment of spa mineral and staining problems start with a water analysis, to help understand the nature of the problem.  The proper chemicals and use can solve virtually all spa staining and discoloration issues.  Don't let unwanted minerals ruin your day.  Test and treat. Liquid MetalTrap

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How to treat mineral, scaling, discoloration or staining problems, in spas, swim spas or hot tubs? Mineral content in spa or hot tub water can lead to a variety of problems: scale, formation, cloudy water, staining of the underwater surfaces, discoloration of the water.  Control of calcium hardness, total alkalinity, pH, trace minerals and maintaining a proper overall water chemistry is important, to help assure optimum water quality. Minerals such as iron, manganese and copper are the principal offenders. Iron and manganese can occur naturally in water, especially well water. High hardness (hard water) can lead to cloudy water and the  loss of filter and heater efficiency, due to scale formation.  When the new source water contains sediments, a METALTRAP Dual-Cartridge Filter can removes both the precipitated metals, as well as the dissolved metallic ions, greatly reducing the risk of staining and helping to keep unwanted sediments from dissolving. If problems arise, refer to the Spa 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.

Do you know what's in your water?  If you're having problems, with stains and discoloration, due to the presence of metals, you should be testing for iron and copper, to better understand the extent and cause of the problem.  This helps select the best treatment option.  Understanding the nature of the problem, should be step one.  For information about our full selection of testing options, visit our Test Equipment Store.  For information about treatment options, visit our Stain Treatments Store.

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▼     Helpful, Problem-Solving Information, in a question and answer format.     ▼

What To Do About Hard Water And Sanitizing?

What is the best spa treatment for health generally and for hard water specifically? Thank you.

Laura M., 2/14/2018

How hard is hard?  Over 400 PPM and calcium hardness problems need to be addressed.  If you can, by all means use the softened water, if your water is of poor quality, is very hard or could contain dissolved metals.  Otherwise, you could be in a heap of trouble.  After the sCard On Guard, Solar UV Sanitizer, for pools and is filled take a sample into a local dealer for a water analysis.  You will need to adjust the calcium hardness, total alkalinity and the pH to compensate for the use for softened water.  Once done, it should be treated like any other spa.  Not all water softeners can remove iron and other heavy metals.  You could use Liquid METALTRAP to treat any iron present or use the METALTRAP Filter to actually remove the iron, from the water.  If you don't have soft water available, you should try to keep the pH closer to 7.2, but not below.  Adding a calcium scale treatment can help.  The Magnetizer is a device that helps to minimize issues, resulting for high hardness.  It simply attaches to a pipe.    Your best options are chlorine (dichlor or lithium) or bromine, along with something to help to reduce the amount used.  Controlling usage helps to avoid further chemical build ups and lessens the downside of high calcium hardness.  Adding an ozonator or a Solar UV Sanitizer can help reduce chlorine or bromine usage and make pH control easier.  In place of chlorine, you could use a salt chlorine generator.  There are several automatic models, as well as others that require no installation.  I hope that I have been helpful.  If so, please tell your friends and dealers about the website.

Sincerely.  Alan Schuster, 2/14/2018


What Caused Greenish-Brown Water?

Changed the tub water a few weeks ago. Everything was in check. I used a filter when refilling the tub attached to the garden hose. I believe I even added a bit of metal treatment. Everything at the time was perfect. Used it a few times, shocked the tub after use each time.  I went out two days ago and noticed a cloudy blue water. I was out of bromine so I added some chlorine in hopes this would clear up the problem, as I thought that chlorine changed to bromine.  Well, yesterday I went out again and noticed that the water was now a brownish green color. I could see the bottom of the tub so it had a bit of transparency to it.  Any idea what the problem could be? Is it a mineral problem? a metal problem? algae? I'm leaning towards the metal problem, as I know that the metal treatment's effect can diminish over time and not work with certain pH values. PS  The alkalinity levels were low so I added alkalinity up. Then the pH levels were through the roof, so I added pH down.  Haven't checked today, as it's still early and I'm at work.  Any help would be greatly appreciated!  Thanks so much!

Greg P., 1/5/2018

A filter can remove sediments, but not dissolved metals. A MetalTrap dual-cartridge filter will do both. The first cartridge will remove sediments and is washable and re-usable. The second removes the dissolved metals and could last long enough to refill the spa over a dozen times. It is a
SmarterSpa Salt Chlorine Generator for Spas. good long-term investment, as it eliminates metal treatments, some of which deteriorate over time or don't work at a pH higher than 7.8.  The greenish-brown color could be due to copper corrosion, caused by low pH, and the presence of iron. Lack of proper sanitation could have added to the problem, as well. Have the water tested for copper and iron. If you are unable to maintain a proper chlorine/bromine level, then you have to add more chlorine product or shock, until the water clears. Don't drag this out, as that only increases the amounts required.  Adding a SmarterSpa salt chlorine generator will simplify everything. It only produces chlorine, when it is actually needed. You'll never over-chlorinate again. It require NO installation and operates independently of the pump. It will cause the pH to rise over time, so all you need to do is add some pH reducer, as needed. This will prevent heater corrosion. If you add 8-ounces of a liquid sodium bromide product, with each refill, you will essentially be operating on bromine. There are other models, on the website, but this one would be my first choice.  I hope that the information provided was helpful.

Sincerely.  Alan Schuster, 1/5/2018

Treating The Stain And Discoloration Problem The Right Way?

Hello We have a new hot tub with well water. The first time we filled it, we added the stain and control 1 with no concerns, water looked great. Then when we refilled it, the tub looks stained, because when we take a cup of water out of the tub it looks clean. Only difference was that the technician said we don't have to add the stain and control 1 till it is 85 degrees or the next day. Could this be the reason for the staining? How quickly are you supposed to put in the bottle?

Cal, 11/24/2016

What you were told makes no sense.  Waiting only assures that staining and discoloration are more likely to occur.  At the very least, I would haveMetalTrap Dual-Cartridge Filter, for pools and spas. told you to add the metal treatment, as the spa is being filled, so that it can react before staining or discoloration can take place.  You will face this problem, every time you add water or refill the spa.  It is not a one time only problem, but is an ongoing concern.  Some metal treatments don't fare well, over time, and allow for a recurrence of the problem.  Avoiding the problem is a better strategy.  Attaching a MetalTrap Dual-Cartridge Filter, to the hose used to fill the spa, will remove dissolved metals and sediments, before the water is added to the spa.  It is a one-time investment, that can provide effective mineral removal, for years of refills and top offs.  Avoiding the problem always tops treating the problem.  If the spa walls are stained, I would add some MetalTrap Stain Remover and drain and clean the tub.  Afterwards use the MetalTrap Dual-Cartridge filter to refill the spa.  This filter comes in 3 sizes and each will remove up to 1 PPM total, of copper, iron and manganese, from its rated volume.  If the total metals content is over 1 PPM, it will treat proportionately less water.  The metals removing cartridge is replaceable.  The other cartridge removes sediments and is washable and reusable.  The smallest size might be OK, but having a spare metal removing cartridge might be a good idea.  I hope that this information is helpful.

Sincerely.  Alan Schuster, 11/24/2016

Should you be testing your water, for  Iron and Copper???

ColorQ COPPER 5 Digital Water Analyzer for pools and spas. 3611 Met=Chek Copper and Iron Test Kit ColorQ PRO 9-Plus Digital Water Analyzer for pools and spas.
ColorQ Copper 5 MetChek Test Kit ColorQ PRO 9-Plus
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Pre-Treating For Manganese?

I am confused. I want to filter the water coming from the hose, for manganese??? I have a 200 gallon spa. Do I just need the pre-filter that attaches to the hose, or do I need something else also? Thanks.

Terry K., 4/13/2016

The MetalTrap Pre-Filter will remove fine sediments and particulates, but will have no effect on the dissolved manganese, copper or iron.  These anyMetalTrap Dual-Cartridge Filter, for pools and spas. dissolved heavy metals are not removed, they will lead to staining or discoloration, after reacting with chlorine or other oxidizers.  If you have sediment-free water, you should use a MetalTrap Filter to treat all new water additions.  Even the smallest size, will last for years, as it can remove up to 1 PPM of metals, from 10,000 gallons of water.  However, if sediments are present, you should use the MetalTrap Dual-Cartridge Filter.  The first cartridge removes the sediments and is washable and reusable.  The second cartridge removes any dissolved heavy metals, such as iron, copper and manganese.  This cartridge can be replaced, but not reused.  It can remove up to 1 PPM of heavy metals, from 28,000 gallons of water, so it should provide many years of being able to treat water used to refill the spa.  In the long run, it is better to properly treat the problem and avoid the staining and discoloration.  I hope that this has been helpful.

Sincerely.  Alan Schuster, 4/13/2016

Purple Sediment?

I have purple sediment all over the bottom of the hot tub. It is not a stain, it looks like crystals. They are not covering the filter, but there are some in the filter. They settle in the low spots of the tub (seats, floor, etc) I am trying to avoid draining since I live Northern California during a big drought. I use chlorine crystals to sanitize the tub. I hope you can help. Thank you

Kevin W. California, 10/24/2015

My guess is that at some point, the pH was low and that lead to copper corrosion. Low pH makes the copper heat exchanger vulnerable to corrosion. Adding a dose of Liquid MetalTrap will help prevent heavy metal pr
oModel SV battery-powered Spa Vacuum.blems, but is not substitute for proper chemistry. So far as the sediment is concerned, I suggest using a battery-powered spa vacuum. It will collect the sediment inside its built-in filter. The purple sediment could be the end product of copper reacting with the cyanuric acid, contained in the chlorine granules.  Efficient removal will help avoid future problems. Adjust the pH to 7.2-7.6, as needed. pH is always the more important parameter! Water left to its own devices will slowly drop in pH, due to absorption of carbon dioxide. If the TA is under 80-120 PPM, add some TA Increaser (baking soda). If the TA is 80-120 PPM, you're perfect. If the TA is higher, you may not have to do anything. There is no compelling reason to have to lower the TA, if the pH is in range and there is no sign of scaling or cloudy water. If the calcium hardness is over 400 PPM, you might keep the pH closer to 7.2-7.4. I hope that this information will prove helpful.

Sincerely.  Alan Schuster, 10/24/2015

Use Of Softened Water In A Spa?

I just purchased a spa and, following the directions, filled it after bypassing my water softener. My well water contains a fairly high degree of iron and manganese. The result was a spa full of "rust" that the filter was able to remove. However, a rust ring builds up daily on the water line. I spoke with the dealer, he advised that I can fill the spa with soft water. So I drained and refilled the spa with soft water. The ring has been eliminated and, except for a slightly cloudy appearance, the spa is great. Why does the manufacturer recommend NOT using soft water? I want to make sure that I'm not doing any long term damage. Thanks for your advice.

Dave V., Rehoboth, MA, 2/16/2015

If your household water is of such poor quality as to require a water softener, it should not be used in your spa. The reason being that certain dissolved minerals might be present and might cause discoloration and staining problems. While it may be
possible to treat the MetalTrap 1-Micron Pre-Filter.dissolved minerals with a quality Mineral Treatment, such as Liquid METALTRAP, I firmly believe that it is easier and less expensive to use softened water - if you have that option! Your experience confirms this! You can easily add chemicals to adjust the pH, hardness and total alkalinity of the softened water and, by doing so, avoid any possible corrosion problems. The balancing of the pH, hardness and total alkalinity, of the softened water, should completely eliminate any objections by the spa manufacturer. The dealer gave you the right advice! Why don't spa manufacturers include such advice? You would have to ask them, but I suspect that because so few people, nationwide, use softened water, they chose not to complicate spa ownership by necessitating softened water in certain areas. It's just not always required. There is an alternative that is widely used to solve this type of problem, when there is no water softener or pond or river water is used to fill the spa. The METALTRAP Filter will permanently remove the heavy metals that might otherwise cause staining and discoloration. The MetalTrap 1-Micron Pre-Filter can remove organic products, that could cause odor and staining.  I hope that I have been helpful.

Sincerely. Alan Schuster, 2/16/2015

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Using Mineral Salts And Total Hardness Relationship?

I have a 450 gallon hot tub.  We have soft water, so I added 20 oz. Calcium increaser, which brought the Total Hardness up to 250 ppm, the minimum OK on the test strip.  Then I added 1.5  kg of dead sea minerals, for the health benefits (Potassium/Magnesium rich).  The description said it was for spas and would not affect water chemistry. Now my total hardness is between 500 and 1000 on the test strip.  The water is clear and feels fine, and Iíve seen no scaling on the acrylic or tile surfaces.  The pH is 7.2, Alkalinity 80, and Iím using an ozonator, Mineral Sanitizer and MPS.  My question is whether itís ok to have a total hardness that high, when much of that is Magnesium, or could it harm the equipment?

Warren H., Cascade Mountains, Washington, 12/12/2014

The statement "for spas and would not affect water chemistry is misleading", as it has resulted in a change, in the water chemistry.  Total Hardness measures the content of both calcium and magnesium.  You obviously raised the magnesium content, so the rise in total hardness is not unexpected.  The testers in use either measure calcium hardness of total hardness.  Calcium is the mineral that we want to control and monitor.  Its salts are usually far less soluble, than the magnesium equivalents, and are very unlikely to cause scaling problems.  Next time, if you are going to add mineral salts with magnesium, you might forego the calcium hardness addition.  I don't see a problem here.  Enjoy the hot water experience.

Sincerely.  Alan Schuster, 12/13/2014

Use Of Well Water In A Spa?

We have a vacation home and plan on adding a spa. We use well water, which does contain some iron. For many household uses, we used bottled water. I have been told that this can cause problems. What would use suggest?

Phyllis T., Boone, NC, 9/10/2013

METALTRAP Filters remove iron, copper and manganese.
Iron can be treated and it is a real advantage that you are able to plan ahead. The METALTRAP Filter will remove iron and other heavy metals, as
you fill the spa. It simples attaches to a garden hose and can treat up to 10,000 gallons of water. That means you will be able to treat all water added to top off the level and refill the spa, many time over. If not treated, the iron will cause staining and or make the water good unappealing. This cartridge-like device traps the iron inside and that is as good as it gets. A much better way than any chemical treatments.  I hope that this information will prove helpful and that it helps make the Hot Water Experience more enjoyable.

Sincerely. Alan Schuster, 9/10/2013

Adding Epson Salts To A Spa?

Can I add some Epsom salt to my chlorine maintained spa without causing a problem.  I plan to add 3 pounds to a 375-gallon spa.  I am hoping it will help with a skin condition.  Thank you.

Ken K., Deerfield Beach, FL, 1/6/2015

I don't see it causing an issue, unless the calcium hardness is over 300 PPM.  It would be important to keep the pH at 7.2-7.8.  I am not sure about the health benefits.  Epsom salts are used in Floatation Tanks, but the level is much, much higher.  I would not recommend that type of level, out of concern for what effect it might have on the spa. I hope that this has been helpful.

Sincerely.  Alan Schuster, 1/6/2015

Hard Water, Iron And Softened Water?

I live in an area with hard water and iron. The iron is so bad that it stains everything but it is effectively removed by the water softener. I have been advised not to used softened water in my spa due to the difficulties in balancing. I drain the spa for the summer but am considering refilling it from the pool as the sand filter effectively removes the iron color. I use chlorine in the pool and bromine with ozone in the spa. Do you see a problem here? Thanks, great web site.

Frank, Nova Scotia, Canada, 9/10/2005

METALTRAP Filters remove iron, copper and manganese.
The dealer is thoroughly wrong! It is not difficult to balance the spa water, if you use a water softener. It is certainly not
easier to deal with the iron and hardness! By all means use the water softener and add a calcium hardness booster to raise the level to about 200 PPM.  Softeners do not always remove metals. A METALTRAP Filter can be attached to the hose garden, used to fill the spa, in order to remove dissolved heavy metals. It will remove the heavy metals, as the water passes through the cartridge-like filter.  Adjust the pH and total alkalinity, as necessary, and you're good to go. Using the pool water is a reasonable alternative. I hope that I have been helpful.

Sincerely. Alan Schuster, 9/10/2005

Well Water Containing Sulfur?

I observed floating particles in our hot tub. The flakes are yellow in color, have the texture of dead skin and can be up to half an inch in size in some cases. We use water direct from our well which contains 5 ppm of sulphur. When I asked our local dealer about the problem, he stated that this is due to the sulphur attacking the lining of the rubber hose plumbing. The sulphur eventually lifts off flakes of the hose which take on the color of the sulphur. He said that the remedy for this is to use a stain control product which keeps the sulphur particles suspended (sequestered) in the water thus keeping the sulphur from etching the rubber lining. He said that this can begin to occur after about sixteen months of use which makes sense in our case. I have begun the use of the stain control and will continue to observe for improvements. Have you ever seen this condition or heard of this remedy?

Dennis, Canada, 1/12/2007

MetalTrap 1-Micron Pre-Filter.
You can't sequester sulfur. But there is a solution. The METALTRAP 1-Micron Pre-Filter will remove lots of the minerals that cause odors
and discoloration. Use it every time you fill the spa and you'll save yourself a lot of problems.  If this is the only source of water, I would bring in a sample of fresh water and have it tested for pH, TA and calcium hardness. I would allow the chlorine level to reach zero, add a 1/4 pound of METALTRAP Stain Remover and let the water recirculate for at least 12 hours. Drain and clean the spa. Use a METALTRAP 1-Micron Pre-Filler to treat the new water, as the spa is being refilled. Always pre-filter new water. Adding a monthly dose of calcium scale treatment is a good idea, if the hardness level is over 400 PPM. For best results drain and clean the spa, every 3-4 months.  I hope that this information will prove helpful.

Sincerely. Alan Schuster, 1/13/2007

Well Water Causing Discoloration?

Awesome site and thanks for the help up front. I have had a spa at my cabin since last September. The water was cloudy and needed to be changed because it was a couple of months old and had an odor. I drained the tub completely via the drain port and wiped down the interior. I refilled the tub with water, which holds about 450 gallons, from my well. The water was tested when we bought the cabin and has very little iron in it. However, I do think we have sulfates dissolved in the water because we do have a tinge of sulfur smell. I have suspended solids in the water and need to get a micro-filter to capture the solids that settle out on the bottom of the tub, but that is another story. I added 16 oz of metal treatment. I added shock treatment, installed a new bromine cartridge and some type of water polisher that is supposed to help clear the water. Note suspended solids above. The tub ran for 20 to 30 minutes and then I tested the water. The water hardness was low as were the pH and alkalinity. Added 10 to 12 oz. of calcium based on the calculation that 1 oz will add about 10 ppm to the water. I also adjusted the pH and alkalinity using a spa-up product. I got the pH in range, the alkalinity was high but I've learned that pH is the important number. Bromine seemed good at about 2 ppm. I have an ozonator and a mineral cartridge in the system, which I did not change. I put the cover down and came back in a half hour. Lifted the cover and the water was clear but a yellowish-green color. I've been reading your site ever since. I read a question that talked about copper in the water turning someone's hair and nails green. I didn't jump in to see if the same would happen to me. Any thoughts? This didn't happen when the tub was filled the first or second time, but the third time was not the charm. Thanks.

Dan K., St. Paul, MN. 3/20/2010

Spas that turn color after chlorine has been added usually have a metals problem, leading to staining and/or discoloration.
METALTRAP Filters remove iron, copper and manganese. This can be very common with well water. ASAP add at least a double dose of a quality metal, such as phosphate-free Liquid METALTRAP treatment. This might help avoid staining and should make an improvement. Bring in a water sample to a local dealer and have the water tested for iron, copper and other parameters. I suggest adding a dose of metal treatment for each 0.5 PPM of metals. Add another dose prior to adding new water. A monthly dose is an additional safeguard against a recurring problem. A metal and mineral removing pre-filter could make a big difference, when used to treat all new water. In the future, you should consider using a METALTRAP Filter to remove the metals, as the spa is being filled. A single METAL TRAP Filter will last loner enough to fill the spa, more than a dozen times.  I hope that I have been helpful.

Sincerely. Alan Schuster. 3/20/2010

Tannins In Well Water?

I have well water and it contains tannin. Do you know how I can filter it out of the water? Thank you.

Amy R., 3/28/2007

MetalTrap 1-Micron Pre-Filter.
Tannins will turn the water a tea color. You should be able to destroy them, merely by adding some extra chlorine. Raise the level to 5 PPM. Well water can contain metals and you should treat the water, by adding a metal treatment. To be on the safe side, you might consider using a MetalTrap 1-Micron pre-filter, as it can help filter out particulates and metals found in well water. Use it to treat all new water added to the spa. It will last through many fill ups and the chemicals saving will make it pay for itself. Doing this will save you a lot of headaches, should metals be present. I hope this information is helpful.

Sincerely. Alan Schuster, 3/29/2007

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