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Bio-Lab provides many products designed to help reduce and remove metal related discoloration from pool water and surfaces. Metals such as copper and iron are typically removed by multiple applications of Quick Clear in conjunction with a chelating agent such as Pool Magnet. Manganese, present in many water sources, especially well water, requires a slightly different procedure for the fastest removal.

Symptoms when Manganese is Present

The main indicator of manganese being present in pool water is the distinctive coffee brown colour of the water. Usually the water is clear until chlorination is started, or the pool is shocked, then it becomes dark brown and cloudy. The coffee brown colour is caused by visible particles of oxidised manganese. These manganese particles are generally filterable, but the length of actual filtration time will vary according to the type of filter and overall operation of the circulation system.

The following alternate procedure varies from our normal procedure for removing metals. If a chelating agent is used before removing the manganese it may increase the time it takes to clear the water. Filtration of the suspended and oxidized manganese from the water is the key to removal; a chelating agent will put some of the metal back into solution, thus interfering with attempts to remove it.

The Procedure

1. Check the fill water for manganese using the Bio-Lab manganese test. If manganese is present, use the following alternate procedure for removal. Anytime manganese is present, regardless of other metals, the alternate procedure should be followed. Make the customer aware that manganese may turn the pool water brown and that there is a chance of temporary staining.

2. Fill the pool. Do NOT add any chelating agents. If the water has a low pH or alkalinity, adjust with proper additions of balancing chemicals.

3. Chlorinate the pool by adding a stick or tablets to the skimmer. DO NOT SHOCK; this makes the manganese drop out very quickly and may increase the chances of staining.

4. The pool will turn cloudy brown upon chlorination; this indicates that manganese has become insoluble and filterable. Filter the water 24 hours a day until it clears. The use of a filter aid (e.g., BioGuard Quick Clear) will increase the efficiency of the filter and aid in removal of manganese from the water. Remember to backwash as needed, but at least every 24 hours when using Quick Clear. The use of an auxiliary DE filter will also decrease the time required to filter the manganese out. Filtration time will depend on filter type, circulation efficiency, mount of manganese present, and water balance.

5. An application of a flocculating agent, such as Liqui Floc, used according to label directions, will help settle the manganese to the bottom of the pool. CAREFUL: The longer settled manganese sits on the bottom of the pool the greater the chances of discoloration occurring. Vacuum the settled metals to WASTE, not into the filter. Liqui Floc settles debris; it does not make them larger. Therefore, the debris may go through the filter and back into the pool.

6. When the brown colour is gone, balance the pool as indicated by the water analysis. A chelating agent (BioGuard Pool Magnet) can now be added to help prevent future problems when fill water may be added. Once the majority of manganese is removed, the necessary addition of small amount of fill water should be added through a skimmer with chlorine tablets or sticks present. This acts to oxidise the metals before the filter and reduces the amount getting back into the pool.

7. If surface discoloration has occurred, whether on the bottom (most common) or sides of the pool, use the following procedure for reduction of the stain.

  • Turn circulation off for 8 hours.
  • Slowly, and as close to the surface of the water as possible, pour three litres of Pool Magnet per 37,000 litres down the sides of the pool in the vicinity of the stain. Allow the pool to remain static for 24 hours.
  • After the waiting period, turn the circulation on and brush the pool. The stain should be reduced or even removed. Circulate water and utilize Quick Clear on the filter to remove redissolved metals from pool water.

The above information is supplied by Bio-Lab and represents its best interpretation of available technical information at the time of preparation. The sole purpose is to supply factual information to Bio-Lab customers. It is not to be taken out of context nor used as support for any other claim not made herein.