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Iron Pool Water Problems

Cause of most pool staining and discoloration problems.
The Pool and Spa Informational Website

Causes, Sources, Treatments and Solutions.


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!

METALTRAP Filters remove iron, copper and manganese. ColorQ #2067 PRO 9-Plus. Stain Reversall Kit.
Dual-Cartridge Filter System. Iron Test Kit
MetalTrap 1-Micron Pre-Filter. The right water tester can help determine the nature and extent of any iron and metals problems.  The #2067 ColorQ PRO 9-Plus tests for iron and copper and 7 other test factors.  The right chemicals or products will complete the treatment.  Don't let iron ruin your day. Solve the problem. Liquid MetalTrap

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How to treat iron problems, in swimming pool water? Iron makes its presence known as a rusty or amber-brownish stains or even as a green - amber - rusty-brown colored pool water. In certain areas, iron is a fairly common pool water problem and is especially true, if the water is sourced from a well. The discoloring pool problems are related to the dissolved heavy metals, that are oxidized, as chlorine or shock is added. Iron can be treated with Mineral Treatment Products (chelating agents). It is important to add an excess amount of product, in order to make sure that enough has been added to treat all of the iron and other problematic minerals. that might be present. Stain avoidance treatment should be used, whenever a water analysis indicates even a trace amount is present. Choose a product such a Liquid MetalTrap, which is phosphate-free and works over a very wide pH range. There is no sense in trading an iron problem, for a phosphate problem.  An alternative method of dealing with known iron and heavy metal problems is to use the METALTRAP Filter, which can physically remove the metals, as the pool water is being added.  If the new water contains sediments, a METALTRAP dual-Cartridge Filter can remove both ion-containing precipitates, as well as dissolved iron and other heavy metals.  Iron and other heavy metal problems can treated with Pool Refresh, used in conjunction with other METALTRAP products. 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.

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.

There are many causes of stains and discolorations, which can appear in a variety of colors.
The color can sometimes point to a cause and solution.  Water Testing can help verify the cause of the problem.

Stain or Discoloration Color Cause and Treatment
Green or Brown

Most likely, these are organic, in nature, and are due to algae and/or tannins, leaching from many common varieties of tree leaves.  This is more likely to happen, if the sanitizer (oxidizer) levels are low and/or if there is poor circulation, across the pool floor.  Superchlorination and improving circulation, are the best course of action.

Dark Blue, Green or Black Dark blue, green or black colors or mixtures are likely caused by copper. High calcium hardness levels tend to cause the stains to darker, in appearance.  The source could be corrosion of the copper heat exchanger, natural sources, over use of copper algaecides, ionizer or mineralizers.  This type of problem requires proper chemical treatment, such as provided by the MetalTrap Stain Reversal Kit.  If present in the source water, a MetalTrap Dual-Cartridge Filter can be connected to the garden hose, used to add new water.  This will help prevent the addition of more metals, with each new water addition.
Green, Brown, Tea-Colored or Rusty-Red Green, Brown, Tea-Colored or Rusty-Red colors are usually indicative of an iron problem.  The most likely source is the water being used to fill the pool.  This is especially true, when well water is used.  While the use of a MetalTrap Stain Reversal Kit will help solve the problem, a MetalTrap Dual-Cartridge Filter should be attached to the garden hose, in order to avoid future recurrences.
Brown, Black or Purple Brown, Black or Purple colors are usually an indication of manganese being present.  This most often occurs, when well water is being used.  A test of the source water should confirm the presence of manganese.  While the use of a MetalTrap Stain Reversal Kit will help solve the problem, a MetalTrap Dual-Cartridge Filter should be attached to the garden hose, in order to avoid future recurrences.
Red or Blue Red or Blue Stains can be associated, with the presence of berries or vegetation.    This is more likely to happen, if the sanitizer (oxidizer) levels are low and/or if there is poor circulation, across the pool floor.  Superchlorination and improving circulation, are the best course of action.
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▼     Helpful, Problem-Solving Information, in a question and answer format.     ▼

Dealing With Iron, Before A Problem Happens?

I have close to 1 PPM of iron in the water, that will be used to fill my pool, inground 20,000 gallon vinyl lined. What should I do, to avoid problems with staining?

Jack B. Jackson, NJ, 7/23/2018

After the pool is filled, most of the iron may be in solution and some may be in suspension. POOL REFRESH, is a 2-part product, that will help precipitate the iron and other heavy metals, so that they can be vacuumed and filtered to waste. Nothing beats, physically removing the iron. And this will help remove any phosphates, as well. After this is done, I would
add a quart per 10,000 gallon of Liquid METALTRAP. This true, phosphate-free, chelating agent will scavenge up any remaining traces of heavy metals and keep themStain Reversall Kit. in a harmless state. Wait a day, for the chelating agent to find all remaining traces of heavy metals. During this entire process keep the filter going 24/7. Now, you're ready to adjust the water chemistry and sanitizer levels. During the course of the season, it will be necessary to add water, due to evaporation, splashout or backwashing. Use a METALTRAP Filter, connected to a garden hose to treat all new additions of water. The metals will get trapped in this cartridge-like filter and be kept out of the pool water. Next spring make sure that the METALTRAP Filter is used to treat the new water.  To add an additional degree of protection, each spring add a quart of Liquid Metal trap, per 20,000 gallons, if the previous steps were followed. This may sound complicated and tedious, but I can assure you it is a lot simpler and less expensive that dealing with the staining and coloration, that untreated iron and heavy metals can cause.  Planning ahead was a wise thing to do.

Sincerely. Alan Schuster, 7/24/2018

How to deal with Iron stains and contamination.

These products remove metals and avoid future, recurrent problems.
Don't just treat stains . . . eliminate them and prevent their return!!!
Stain Reversal Kit. Liquid MetalTrap MetalTrap Stain Remover. Pool Refresh eliminates phosphates and metals, from pools and spas.
Stain Removal Kit
Liquid Metal
Chelating Agent
Stain Remover
Eliminates Metals and Phosphates
MetalTrap Dual-Cartridge Filter, for pools and spas. MetalTrap Single-Cartridge 5-Micron Filter System, for pools and spas. MetalTrap Filters remove heavy metals. MetalTrap 1-Micron Pre-Filter, for Pools and Spas.
Filter System
5-Micron Single Cartridge Filter System Filters for Heavy Metals Removal 1-Micron
Visit The Metals and Staining Treatment Store for complete information.

Do Some Metal Treatments Break Down?

I have treated my pool with products containing organic phosphonic acid and, while it seems to help, over time the problem returns. Is this because the chemical breaks down?

Janet H., 8/9/2016

MegaChlor salt chlorine generator, for spas and swim spas.
That type of product is known to degrade over time, allowing for a return of the problem. As it degrades, it forms ortho-
phosphate and that can leave you with a phosphate problem. In addition, its effectiveness is limited, if the pH is over 7.8. If you have a salt chlorine generator or plan to add one, that type of product is not the best choice. A salt chlorine generator tends to keep the pH at 7.8 or higher, unless daily attention is paid to the pH. A product, such as Liquid METALTRAP is phosphate-free and is unaffected by the pH of the pool. There are other METALTRAP products to help you remove metals, from new water additions and products to remove stains. I hope that this will help you resolve the issue.

Sincerely. Alan Schuster, 8/9/2016

Iron Stains?

There is an amber-brownish colored stain in the deep end of my vinyl liner, in-ground pool. According to the dealer, I have 0.2 PPM of iron. He is not sure that it is an iron stain. What should I do? Thank you for any help.

G.F., Milton, PA, 7/14/2017

It is probable that the stain is iron. We know there is iron present in the water and 0.2 PPM of iron is enough to cause a pool water problem. First start by adding a dose of Liquid MetalTrap: a quality, phosphate-free, Mineral Treatment Product, that
METALTRAP Filters remove iron, copper and manganese. works over a wide pH range. This will chelate (complex) with iron and help prevent further staining. To determine, if the stains can be removed with an acidic solution try this: put a 1/2 pound of pH decreaser in a white sock and drop onto a stained area. Leave in place for about 10 minutes. If improvement is seen, as expected, a very practical method of removal would be to use a stain-remover accessory. This gadget (available at many pool stores) will allow you to siphon an acidic solution onto the stains. To make a suitable solution: to a 1/2 gallon of water, in a plastic container, add 1 quart of a Liquid MetalTrap and 1 quart of muriatic acid. Make sure that you wear rubber gloves and eye protection!  Use the stain-remover accessory to siphon the liquid onto the stains. If the area is large you might want to allow the chlorine to bottom out and then add ascorbic acid, as directed. Give it a day or two, before adjusting the pH or adding chlorine, as necessary. There is another non-chemical solution, to the problem. Using the METALTRAP Filter, you can treat all new water, which helps keep new additions of iron and other metals out and minimizes the possibility of staining. You could, also, use The METALTRAP Filter to recirculate the pool water and lower the iron and heavy metal content, already present in the pool water.  I hope that these instructions will prove helpful.

Sincerely. Alan Schuster, 7/15/2017

Turned Brown?

Dear Alan, we have put up a small pool (2400 gallon) that was a kit from a local store, complete with a water pump/filter, cover and such. Problem is we filled it from a well. The well is known to have both iron and sulfur in the water. When I added the initial set of chemicals (stabilizer, shock and chlorine) the water turned real brownish in color. I presume (from one of your articles) it's because of the iron, but I'm also wondering about the sulfur. Do I only need to address the iron issue with a chelating agent, or do I need to do something special for the sulfur too? Thanks and Regards,

Mitch, 5/18/2012

A quality mineral treatment (chelating agent) is one of the proper treatments, for the iron problem. Liquid METALTRAP is
Liquid MetalTrap. especially well suited, as it is phosphate-free and works over a wide pH range. It works best before chlorine has been added or the pH has been increased. In fact, you should to add the product as the pool is being filled. If you would have used a METALTRAP mineral removing filter, which attaches to a garden hose, you might have been able to remove a lot of the particulated iron and other metals. Using it on all future water additions, also makes sense. A shock treatment should take care of the sulfur. Make sure that there is a 1-3 PPM level of Free Chlorine, that persists for an over night period. The sulfur will be oxidized to harmless sulfates. I hope that I have been helpful. Enjoy the pool.

Sincerely. Alan Schuster, 5/19/2012

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

ColorQ COPPER 5 Digital Water Analyzer for pools and spas. 3611 ColorQ PRO 9-Plus Digital Water Analyzer for pools and spas.
ColorQ Copper 5 MetChek Test Kit ColorQ PRO 9-Plus
Click any image, for product and ordering information.

Rusty-Brown Water?

The area that I live in has iron in the water. Several times, in the past, I have had the pool water suddenly turned rusty or brown, right after I added some chlorine. I'm sure that it was because of the iron. The dealer had me treat the water with a chemical and everything seems to be all right. Is there something that I can do to avoid it from happening again?
Betty J., Littleton, MA, 6/2/2009

In all likelihood, the dealer had you add a Mineral Treatment, that was a chelating agent, but may not have been phosphate-
free.  Liquid MetalTrap is phosphate-free and works over a wide pH range. Hopefully, you are not exchanging aStain Reversall Kit.n iron problem, for a future phosphate problem. This complexed the iron and allowed it to remain in solution, without discoloration or staining. From now on, it is important to add this chemical before any make up water is added. In addition, I would add some every month, just to make sure that there is an excess. The iron is still in the water: it has been chelated and is now soluble and colorless and you want to keep it that way. Springtime opening: add some more. Pool closing: add some more. It may sound like overkill, but it will save you aggravation and the possibility of staining and discoloration problems. Considering that your water is known to contain iron, there is another solution, to the problem.  A MetalTrap Stain Reversal Kit contains a regimen of products, that will dissolve the stains, help you vacuum and filter the metals out of the pool and help avoid a recurrence. Afterwards, you can use a METALTRAP Filter, to treat all new water, which helps keep new additions of iron and other metals out and minimizes the possibility of staining.  In the long run you'll probably save money, by staying ahead of the problem. I hope the advice does the trick.

Sincerely. Alan Schuster, 6/2/2009

Lots Of Rust?

I sure hope you can help, we just purchased an above ground pool, we live in a small town in Illinois on it's own well system the water is very hard and often has rust (iron oxide) in it. We filled our pool using this water now we have the rust settled on the bottom of the pool unless it gets stirred up then the water is brown and nasty looking. What can we do to clean the water, we tried vacuuming the bottom but the deposits are like a fine silt and only stirs not vacuuming up. A rapid response would sure be appreciated my grandkids are so excited they want to get in anyway, but I won't let them.

Diane M., Illinois, 6/11/2009

Avoid adding chlorine and other chemicals right now. I suggest that you keep trying to vacuum as much as possible through the filter and not to waste. Try adding a dose of a "Blue" Clarifier. It should help coagulate the particles for easier removal.
For the lonMetalTrap Dual-Cartridge Filter, for pools and spas.g haul a Nano-Stick Clarifier will work very well, while lasting up to 6-months. It can be used will all types of chemicals and pools. Keep the filter operating non-stop. Try to get as much out as possible and then backwash to waste or clean the filter. Before adding chemicals, have the water tested for iron. For each 0.5 PPM of iron or fraction, add a dose of a quality mineral treatment. Allow to circulate for several hours before adding other chemicals. When adding new water, try and place the hose in the skimmer to allow the filter an opportunity to remove the suspended iron. Precede each new water addition with a dose of phosphate-free, chelating agent, such as Liquid METALTRAP and add another dose on a monthly basis. Well water is almost always a problem and there is a better solution, for the problem. You can use a METALTRAP Dual-Cartridge Filter to pre-treat all new water, which helps keep new additions of iron and other metals out and minimizes the possibility of staining. You could, also, use The METALTRAP Dual-Cartridge Filter to recirculate the pool water and lower the iron and heavy metal content, already present in the pool water. Well water can be a challenge and is best when treatment is started early. Good luck. I hope that this information is helpful.

Sincerely. Alan Schuster, 6/11/2009

Alan, Thank you for your help. A pool owner in our town said that they add pH minus to their pool after filling it up and that clears it up after a couple of applications. We put that in last night then an hour later we shocked, will this cause a problem with the Blue? Thanks once again you are very helpful.

Diane, 6/11/2009

I was trying to help you get the iron discoloration out of the water. Adding the pH minus will dissolve the iron and it will remain in the water. The Liquid METALTRAP should complex the iron and help keep it in a colorless and soluble state. You must add the Liquid METALTRAP and add enough of it. Have the water tested for iron! You can add the "Blue" Clarifier, the following day. Good luck.

Alan, 6/11/2009

Thanks so much, I've passed your information on to the person that told me to use the pH minus so they can try the mineral treatment instead. I loved your website.

Diane, 6/11/2009

Mineral Stain Avoidance?

I plan on filling a 16,000 gallon vinyl pool with water from my private well. I know that there is a low level of manganese in the water. How should I treat the water after I fill the pool up? I hope that you will be able to offer some advice. Sincere thanks.

Don C., Westhampton, NY, 6/26/2007

Fortunately, you know that there is manganese in the water. It would have been helpful to know how much. Testing for Iron and or Manganese is very important for planning a successful treatment. Having lived on Long Island, I know what a problem manganese can be in some pools on the south shore. Those brown-black stains and discoloration are not great to look at. In
ColorQ #2067 PRO 9-Plus. addition to having manganese, it is likely that the water has iron and other minerals. Manganese is frequently associated with a purplish discoloration or stain. The incidence of manganese problems, is for the most part, limited to well water or corrosion of stainless steel. Both iron and manganese can be treated along similar lines. As the water is being fed into the pool, add 2 quarts of phosphate-free, Liquid METALTRAP, for each 1 PPM of iron and manganese present in the fill water. Adding more is better than adding less. After the pool has been filled, recirculate the water for an hour. At this point, you can begin to adjust the overall water chemistry. The early addition of the Mineral Treatment should spare you from the problems associated with manganese. Now, there is a better option! Well water is almost always a problem and there is a better solution, for the problem. The METALTRAP Filter enables you to pre-treat all new water, which helps keep new additions of iron and other metals out of the pool water and minimizes the possibility of staining. You could, also, use The METALTRAP Filter to recirculate the pool water, lowering the iron and heavy metal content, already present in the pool water. The METALTRAP Filter does it all and you may not need any chemicals, depending on your water quality. Good luck and enjoy the season.

Sincerely. Alan Schuster, 6/27/2007

Yikes It's Iron?

Alan, when we opened the pool this year, and "yikes" for the first time ever, we have rust all around the pool sides. The winter waterline down, but none on the floor of the pool. Why would we have this problem now? Our water source hasn't changed and it's not well water. Well, my better half decided to put a mineral treatment in the pool (not a lot, but it's still in there). Have we made a terrible mistake? Will our chemical levels be out of whack all summer and will we be able to swim in the pool? Now I am afraid to add any of the chemicals from the pool opening kit. Please help, thanks.

Karen from Ohio, 6/10/2017

If the pool water problem is really iron, adding an iron mineral treatment was the right thing to do! It is possible for trace amounts of iron to be present in tap water. However, that should not have caused the problem. If it is iron, it somehow made its way into the pool. It could have been that the last time water was added, a fire hydrant was opened in the neighborhood.
WaterLink SpinTouch Tester, for pools and spas. This can lift sediments off the bottom and deliver them to your pool. Try this. Put 1/2 pound of pH reducer powder in a white sock, tie a string onto the sock and drape it over the wall of the pool. Let it contact the stained area. If improvement is seen, within 15-30 minutes, it is confirmation that the problem is iron and/or other metals. Source unknown! It might be necessary for you to lower the pH drastically to approximately 6. Use the brush on the walls and keep the filter going. Afterwards, add a triple dose of a quality, phosphate-free, mineral treatment, such as Liquid METALTRAP, to help prevent a recurrence. When everything is back to normal, backwash or clean the filter. This will help prevent the material from being redissolved in the water. Yes, you will be able to swim and the chemistry can be corrected. To better assure proper overall pool water chemistry, visit a pool store that has a very reliable, professional lab such as a WaterLink SpinTouch Lab, rather than a less accurate test kit or strip reader.  I hope that I have provided the solution.

Sincerely. Alan Schuster, 6/10/2017

Using Sodium Gluconate To Chelate Iron?

Please help. I have a pool of 10,000 gallons of water and somehow a lot of iron has been found in the water. Someone told me about sodium gluconate. Is this Ok to use in the pool water to chelate the iron? Also how much would I need to use in 10,000 gallons of water and at what pH? Thank you.

Demetries, A., 10/27/2011

I have never heard of sodium gluconate used in the pool industry, as a treatment for iron. It is considered to be a chelating
Liquid MetalTrap. agent for iron, but at near neutral pH. At the more alkaline pH, found in most pools, it is more apt to chelate the far more abundant calcium. Therefore it would seem a poor choice. In addition, I have no idea of how well it could survive in a chlorine-based pool. On the other hand, Liquid MetalTrap will chelate iron, in the presence of chlorine and over the widest pH range, that might be encountered. It is also phosphate-free. A MetalTrap Filter Cartridge can be used, with a small submersible pump, to remove iron, as the water passes through it. It can also be used to treat all new water being added to the pool. I hope that you will find this information helpful.

Sincerely. Alan Schuster, 10/7/2011

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