manganese pool problems: water chemistry - treating manganese problems in swimming pools

Manganese is one of the more troubling swimming pool mineral problems. This is especially true, if the water is sourced from a private well. Manganese shows up as a brown-black stain or discoloration and thankfully is not common in most areas. Purple staining or even crystal-clear purple water can occur, due to the presence of manganese. Corrosion of stainless steel (contains manganese) can lead to purple discolorations. In most cases the pool discoloration problem, is associated with the oxidation of the heavy metals, that are present in the water. Manganese can be treated with Mineral Treatment products (chelating agent). Higher than normal dosages should be used because of the likelihood that other minerals are present, but not necessarily detected. Stain avoidance treatment should be used, whenever a water analysis indicates even a trace amount of manganese 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.

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 advise. Sincere thanks.

Fortunately, you know that there is manganese in the water. It would have been h

elpful to know how much. Testing for Iron and/or Manganese is very important is planning a successful treatment. Having lived on Long Island, I know what a problem manganese can be 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.

Magnesium chemistry is closely related to that of calcium. However, it is much more soluble in a swimming pool. It is not associated with any staining or colored pool water problems. Magnesium contributes to the TOTAL HARDNESS of the water and unless the water is very hard, there should not be a problem. Manganese is completely unrelated and is almost always the center of a staining and/or a colored pool water problem. Manganese is not common in municipal water supplies. However, in some areas, it can be present in well water. If manganese is suspected of being a potential problem, a water analysis will help determine the concentration. This is important in order to help assure proper dosage. In areas where the problem exists, dealers should test for manganese. I hope that I have eliminated the confusion and been of assistance.

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Hi, Alan, I have a pool service business on the east end of Long Island. There is a manganese problem in some areas of the south shore. Is there a simple test kit that I could use, in the field, to test for manganese. It just might help solve a lot of problems for me. Thanks.

There are compact and portable field manganese test kits that are suitable for your needs. Your customers will appreciate all the aggravation that you're are helping them avoid. I hope that I have been helpful. One more word of advise. Add 1 dose of a quality mineral treatment product for each 0.5 PPM of manganese found. This should provide an excess to help deal with other minerals that might, also, be present. Have a good season.

Sincerely. Alan Schuster, 3/19/2003

Are you sure it's manganese? It is found in some well water. You are not going to remove manganese from the water. At best you will be able to control the staining and discoloration problem that could result. Many products use the work "remove" very liberally, when they really mean "helps control." For each 0.5 PPM, add a dose of a quality metal treatment. Add at least a double dose. Adding it with the pH lowered and a low chlorine level might help the product work better and faster. Allow 6-8, with the pump running. If there are any signs of staining or discoloration, repeat the dosage. If there is manganese present, there could be other metals competing for the metal treatment and there could make additional doses necessary. Thereafter, add another dosage monthly and prior to the addition of any new water. When adding water, place the hose in the skimmer, as this will allow the filter to have a chance to remove any particulated minerals. While is not toxic in a swimming pools at low levels, it could fail to meet the standards for drinking water. If there is doubt, check with the local water authority or health department. Manganese can be a tough problem. Good luck and I hope that I have been helpful. Happy holidays!

Thanks Alan. Yes I'm sure it's manganese. It came in the last batch of salt I put in. I will follow your directions and see how it goes. Great site you have -Very helpful.

It would appear that you used a technical or industrial grade of salt with your salt chlorine generator. That was a mistake. Try to use only a food grade or water softener grade. No rock salt or salt with yellow prussiate of soda! At least you'll know for the next time.

Gunite pool, pink algae year ago, used algaecide to get rid of it, and it worked until it got warm. Then blue-purple color was on the walls, step walls (not on the bottom) of the pool. When got cold, went away. Now with it warmer, it's back. Water testing shows Calcium 600 (that is after 2 1/2 pool drains) chlorine is high, rest ok. Minerals - no iron. Pool people thought needs to be washed. Lowered water 1/2 way, and used liquid chlorine on the steps. What ever the chlorine touched, that was purple in color, TURNED BLACK! The towel I used to put the chlorine on turned warm. It did come off when brushed & some elbow grease. Questions: what is going on, besides a chemical reaction of some type? Should a chlorine wash get rid of this? We are selling the house and need to have it fixed for new buyer. Thank you.

THIS IS DEFINITELY NOT AN ALGAE PROBLEM! IT IS DEFINITELY A MINERAL PROBLEM!. The action of the chlorine turning the discoloration from purplish to black is indicative of an oxidizing chemical reaction. A chlorine "wash" or shock treatment will probably be a waste of time and money. Purple color of the pool water and the colored staining can be indicative of manganese. It is not a common problem and most dealers do not test for it. If your water came from a private well, there is a greater likelihood that manganese could be involved. Another more likely possibility is copper. Copper in the presence of high levels of calcium hardness, which you do have, can cause dark or black stains, under certain conditions. The blue-purple color could have been a faint deposit of copper, normally bluish in color, and the background color of the pool finish. When the pool people suggested a "wash", I suspect that they were referring to an acid wash. This type of treatment is periodically done on masonry pools to remove surface deposits and restore the look of the pool finish. It may be possible to remove the deposits by chemical treatment. Try this. Put 1/2 pound of pH reducer powder in a white sock, shut off the filter and drop onto a stained area. Check after 15-30 minutes. If improvement is seen, this would be indicative that chemical treatment might work. Chemical treatment will require that you add 2-3 doses of a quality mineral treatment, to help prevent further staining and discoloration. Raise the water level above all of the discoloration. Add muriatic acid until the pH has dropped to below 6.0. It may take considerable acid, depending upon the starting pH and the total alkalinity. Without the lowering of the pH, you are not likely to remove the stains. Some pool stores sell oxalic acid. This can help in removing the stains and can be added to the acidic pool. This material will react will chlorine, so add only when the chlorine level is very low. At that point the addition will zero out the chlorine and create conditions more favorable for pool stain removal. Use the brush to help things along. Metal parts in the pool, pump and filter may be affected by the acidic conditions. Clean or bypass the filter, if possible, to remove stain causing debris from the filter. Depending upon the pH, you should see improvement in a day or so. Once the stains are removed, add another 2-3 doses of a quality mineral treatment, before restoring the pH. It will be necessary to shock the pool, in order to destroy all of the oxalic acid and reestablish proper pool chemistry. Where did the copper come from? If you have a heater you may have subjected it to corrosion. Copper algaecide is another possibility. Refer to other related topics in the archives. I hope it works out for you.

Thank you Alan. Yours has been the first sensible response I have had. It does come off with the sock & sodium bisulfate. Took no brushing. We cannot bypass our filter. Can we lower the pH, then bring it back up and still have swimable water? Thank you again.

The purpose of the bypass was to minimize corrosion. Clean the filter out before treatment and again afterwards, so as not to redissolve what you are trying to remove from the pool walls. Don't neglect to add the mineral treatment! Otherwise, you could get a recurrence. You can swim as soon as you restore the pH and the chlorine levels. Inasmuch as the stain was removed without the oxalic acid, I don't see the need to add the product. It seems that things will work out for you. Good luck with the sale of the house.

I have a 97,000 litre pool with a salt chlorinator. Due to local drought conditions in Australia, I now have to use bore water to keep the pool levels for continued use. (My property is on the market). The bore water has Manganese concentration of 2.6 mg/l. The chlorine now produces a black and unsightly precipitate. Alan, is there a product that can be added to the pool water or skimmer box to cope with the manganese problem? What other advice can you give me regarding same? With thanks.

Chris B., 9/13/2007

That is about five times the concentration in marginally drinkable water. I would use a MicroPure prefilter to process all new water. It will remove some of the particles and reduce the problem. Otherwise, treat it like iron, but use a higher dose of metal treatment. At least one dose per 0.5 PPM. Having a DE filter will help. Add another dose monthly and prior to adding new water. A simple and effective way to reduce most minerals problems, resulting for the use of well water, is to use the MicroPure Pre-Filter. This attaches to a garden hose and remove much of the mineral content, that would get into the pool. Makes it easier to treat the pool. Use every time new water is added, for best results. I hope that this information will prove helpful.

Sincerely. Alan Schuster, 9/13/2007

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