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How to Treat and Prevent Pool Staining and Water Discolouration

Clean Stains in your Pool

If there is staining on the liner or concrete in the pool that is dark and not removable by scrubbing, there may evidence of metals in the water. Water may also turn abnormal colours. Metals can take their place in pool water because of metal foreign objects entering the water such as pennies or other coins, copper piping/fittings, the use of Copper Sulphate to clear algae, source water, or when water balance problems causing corroding of your heater. It is best to take a pool water sample to a water lab as soon as the staining or discolouration occurs and tell the technician about the problem. Do not shock the pool!

Filters should be cleaned or backwashed before adding chemicals to treat metals. Allow chlorine/bromine levels to drop below 1ppm or the chemical may not work effectively. This may risk the water turning cloudy or growing algae, but this is something that can be treated after.

Metal stains can be identified as follows:

Metal Stain Colour Water Colour
Iron Orange-reddish stain Yellow-brown stain
Copper Blue-green to black stain Blue-green or black stain

To treat metal staining:

  • 1) You must take a water sample in to a local water test lab to be tested. Always do a bucket test before adding the balancing chemicals to the water. Take a 20 litre bucket and fill it with pool water, then take one cup of the chemical you want to add to the pool and dump it into the bucket. If the water changes colour in the bucket, DO NOT add the chemical to the pool. If nothing happens, it is safe to add the chemical to the pool.
  • 2) After the chlorine level has dropped below 1ppm, add the required dose of Natural Chemistry MetalFree as instructed by the water test lab. Add the Natural Chemistry MetalFree in an area of the pool with the best circulation or areas closer to the stains.
  • 3) Add required amount of Natural Chemistry StainFree to the pool to remove any staining on the surface of the pool.
  • 4) Brush stains daily. DO NOT SHOCK THE POOL!!
  • 5) Three days after the addition of Natural Chemistry MetalFree, add a maintenance treatment of Pool Supplies Canada Super Clarifier or Natural Chemistry Clear.
  • 6) One week after adding Natural Chemistry MetalFree, complete another water analysis. If the metal has been stabilized, we can proceed with bringing the sanitizer level back up.

If the stain is not treated almost immediately, it is inevitable that some stains will become permanent. If it is determined by water analysis that there is no presence of metals in the water, this staining could be organic (caused by elements of nature), or could mean that the metal has come out of solution. Proceed with the same treatment in attempt to remove stains and brushing daily or after your weekly shock treatment. This stain may lift over time through daily brushing and regular shock treatments.

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