Are usually caused by lack of chlorine. Also other factors can cause the affects of green water or algae. Sometimes the mixture of chemicals (minerals, metals ect.) can cause a chemical reaction and give the appearance of green or discoloured water, be sure to have your water tested by a pool professional if you are not sure if it is algae. Algae is an under water type of plant. It is alive, and can grow very fast. Phosphate can add to the development or growth of algae. As phosphate is a plant food and found in a lot of fertilisers it also feeds algae. You can get products to remove phosphate witch is necessary in order to stop the regrowth of algae. In pools that use chlorine tablets, be sure to check the stabiliser (pool sunscreen) level as too much stabiliser can cause a chlorine block and trap your chlorine molecules inside a wall of stabiliser. Your pool will still show chlorine in tests, but it will not kill algae. The guide below is for green pools with algae not green pools caused by chemical imbalances


  1. Test pool water to see if you have phosphate, or metals plus your stabiliser levels. You must remove phosphate or excess stabiliser in order to kill algae effectively. If these levels are fine go to step 2
    If you have phosphate ask your pool pro for a phosphate remover and follow directions on pack.
    The only way to remove stabiliser is to remove water. Draining pool to bottom of skimmer box then refilling with fresh water is advised. This may need
    to be done several times. Test levels after each refill, please check your local water restrictions before filling pool.

  2. Bypass your filter. You want to recirculate the water so as not to clog the filter with any more algae.
    Sand or D.E filter, turn off pump, and set handle to recirculate/bypass
    Cartridge filter, remove cartridge and clean, put tank together with no cartridge 

  3. Turn pump on

  4. Scoop out as much debris out of pool first as this will make an easier job in later steps. Brush all walls and floor to lift algae as it will die easier if floating.

  5. If after brushing you can not see the bottom of your pool, add twenty times your daily dose of pool chlorine ie. If you put in one litre a day, add twenty litres. If it is only a tinge of green, put in ten times your daily dose. Check your P.H level an hour after adding chlorine, as high levels of chorine will cause your P.H to rise; a high P.H will only let ten percent of your chorine work. Adding acid will lower P.H. You may have to add more chlorine if pool is still green after twelve hours.

  6. Run your pump until the green turns to white. This means you have killed the algae and now have dead bleached algae floating around your water.

  7. You have two options at this stage. A. to filter out dead algae, recommended for lighter soiled pools, simply clean filter/s, and run pump through filter until pool clear. A clarifier will help reduce clearing time. Cleaning filter/s at least once a day as the cleaner the filter the more dead algae it can hold.

  8. The other method is to add a flocculant witch will clump dead algae together and sink it to bottom of pool to vacuum to waste. Keep filter/s out or on recirculate, add required amount of floc, as directed on packet, run pump for two hours then switch off pump allowing debris to sink. Normally takes twelve hours. Once settled, set filter to waste, or open waste valve, and set up your manual vacuum, then vacuum the dead algae to waste. Refill pool.

  9. Once pool is clear, take sample to pool shop and rebalance water. All rights reserved © Copyright 2000 -