Treating Your Pool Again

• Chlorine kills algae, and the main cause of algae growth and green pools is insufficient chlorine. Once algae has started to develop, you will need much more chlorine than pools typically use in order kill it. You can add up to three times as much chlorine as you would normally. During your first treatment of the algae, you should have added chlorine to the pool to try to kill it. For a second treatment, increase the amount of chlorine you are adding to the pool. This chlorine will also kill bacteria. Bacteria occasionally affects the color of your water, but much less often than algae.
  
  In addition to adding chlorine to your pool, you will need to use filters to remove the algae and any other contaminants that could be changing the pool's color. Like with the chlorine, the problem with your first treatment could have been not having enough filters. You can rent additional filters from pool cleaning stores to temporarily add to your pool.
  
  

Removing Dead Algae

• If the water has started to turn from the original green color to a more brown shade of green, then at least some of the algae, and possibly all of it, has been killed. In this case, adding more chlorine will not help change the color of your pool. Instead you should rely on pool filters to pull the algae from the pool. Filters will not always remove the algae quickly, so try using many filters and running them for several days.
  
  Above-ground pools can be completely drained to clear up the color. Use a pump to pull the water out of the pool, following the instructions that came with the pump and any instructions that came with your pool. Only drain the water in an in-ground pool if you are sure your pool has the structural integrity to hold together when empty. Once your pool is drained, wipe clean the sides of the pool and refill it with new, clean water and add the appropriate chemicals.