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Removal of iron from the swimming pool water

Iron may get into swimming pool water when the pool is filled up with water, but frequently also due to corrosion of ferrous parts of the system, e. g. of galvanised iron pipes or from stainless steel mounting parts. Most waterworks completely remove the iron contained in natural waters and provide water which is largely iron-free. However, iron can still get into the water on its way to the consumer, for instance if the community piping system still includes iron pipes. For this reason, the water analyses of waterworks in regard to the iron content are not representative for any tangible case.

Even higher levels of iron can be detected in well water, which is usually not connected to iron removal systems.

The consequences of iron in swimming pool water are:

1. When freshly filled up, the water appears clear and clean, but as soon as a disinfectant is added, the water quickly turns brown and muddy. The reason is the creation of tri-valent brown iron hydroxide created by the oxidation of colourless bi-valent iron through chlorine or active oxygen as oxidation agent.
2. The brown iron hydroxide can deposit on pool walls and can therefore lead to unattractive, not easily removable stains.
3. Minimal iron contents cause the water to turn green, without precipitations being observed. The water remains clear, but has a green lustre.

It is recommended to remove iron from the water when starting with the water treatment, i. e. immediately after filling up the pool, particularly in order to prevent residues on the pool wall and floors.

Complete removal of iron is possible with the use of a sand filter system and by flocculation with Superflock Plus. The procedure used in this case is as follows:

1. Carry out a shock treatment with 15 g of Chlorifix/m³ or one Chloriklar tablet/2 m³ in order to oxidise all the iron
2. Adjust the pH level to 7.0 – 7.4.
3. Place a Superflock Plus cartridge into the skimmer (or prefilter of the pump) and let the circulation pump run permanently. Backwash the filter after about three days. Should the iron removal not yet be complete (water is still brownish-muddy or green and clear), add a new Superflock Plus cartridge and repeat the procedure.

Normally, the success of the procedure can easily be observed: As early as a few hours after placing a Superflock in the skimmer or prefilter of the pump , the cloudiness begins to disappear and/or greenish coloured water changes to a bluish colour.

If the iron is not eliminated immediately after the appearance of precipitations, it will become even more difficult to remove it. Newly formed stains on the walls and the floor can be re-dissolved by adding 30 ml Calcinex per m³. In case of older precipitations, it may be necessary to empty the pool completely and clean the walls and the floor with Decalcit Super.
The same applies if manganese is present in the filling water in certain areas. Manganese can be recognised if the water turns dark, almost black, after adding a disinfectant.

Complete removal with Superflock Plus is, however, only possible for iron.

Copper Removal

Removal of copper with Superflock Plus

Copper may be present in swimming pool water by adding algaecides or algae killers containing copper, but more frequently it comes from corrosion of periphery parts containing copper, such as heat exchangers and bronze and brass pumps or fittings.

Information: Copper may already be present in the water the pool was filled up with, the maximum level is 3 mg/l according to the German Drinking Water Directive. Please check with your local authorities what the level is in your area.

Copper in higher concentrations may cause black spots on the liner, black spots on peripheral parts such as ladders or inlets, and in some cases a green staining of blond hair.

In the past, it was recommended to replace copper contaminated water completely. However, with the use of Superflock Plus, it is possible to completely remove copper from the water by following the below mentioned procedure: 

1. Raise the pH level to 7.5 – 7.7 with pH Plus.
2. Place a Superflock Plus cartridge in the skimmer.
3. Leave the circulation pump running for 48 hours.
4. Backwash the filter thoroughly.
5. If necessary, repeat the procedure by adding another Superflock Plus cartridge in the Skimmer (or prefilter of the pump)
6. The copper has been removed completely when the backwash water no longer shows a greenish coloration.
7. Lower the pH level to 7.0 – 7.2 with pH Minus.