Causes, Sources & Solutions

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.  Clicking on the underlined and highlighted "keywords" or "catch phrases," in the archived answers will give you access to additional information on that topic or product.  Please refer to the Glossary, if there are terms or phrases that require explanation.

Iron Test Kits

► 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, 6/10/2003

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.  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 mineral treatment, 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 or Pinpoint system, rather than a less accurate test kit or strip reader.  To locate a dealer near you, go to:  www.lamotte.com/pages/pool/expdeal/index.html  Good luck and I hope that I have been helpful.

Sincerely.  Alan Schuster, 6/10/2003

► 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, 7/14/2003

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 a quality Mineral Treatment Product.  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 quality Mineral Treatment Product 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.  Afterwards, adjust the pH, as necessary.   I hope that these instructions will prove helpful.

Sincerely.  Alan Schuster, 7/15/2003

Need An Iron Test Kit?

Visit The Test Equipment Store, for all your needs.

► 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, 5/18/2003

A quality mineral treatment (chelating agent) is the proper treatment for the iron problem.  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.  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, 5/19/2003

► 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, 6/2/2004

In all likelihood the dealer had you add a Mineral Treatment, that was a chelating agent.  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.  In the long run you'll probably save money too.  I hope the advice does the trick.

Sincerely.  Alan Schuster, 6/2/2004

► 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, 6/11/2003

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.  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.  Even  better would be using a MicroPure Pre-Filter for all new water. Precede each new water addition with a dose of mineral treatment and add another dose on a monthly basis.  I hope that this information will prove helpful.  Well water can be a challenge and is best when treatment is started early.  Good luck.

Sincerely.  Alan Schuster, 6/11/2003

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, 6/11/2003

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 mineral treatment should complex the iron and help keep it in a colorless and soluble state.  You must add the mineral treatment and add enough of it.  Have the water tested for iron! You can add the "Blue" Clarifier, the following day.  Good luck.

Alan, 6/11/2003

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, 6/11/2003

► 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, 6/26/2004

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 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 a quality Mineral Treatment 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.  Good luck and enjoy the season.

Sincerely.  Alan Schuster, 6/27/2004

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