The first step to treating algae is to identify which type of algae you’re wrestling with. Once you’ve pegged the culprit, you can begin the treatment.
Stepping back a bit, though, the best way to treat algae is to never let it become a problem. Proper pool maintenance will keep algae from growing, so be sure that you maintain the right pool sanitizer level to prevent algae from ever forming.
Once you’re faced with algae, check the pH and adjust it if necessary. If it’s green algae, superchlorinate the water (going as high as 30 ppM chlorine) and then wait until the chlorine drops to normal levels, which usually takes about 48 hours. Add an all-purpose algaecide and follow the directions on the packaging. After the algaecide treatment, vacuum the dead algae and backwash the filter. If the algae growth is really heavy, you may need to repeat the above treatment.
If you’ve got mustard algae or black algae, use a stiff brush to remove as much of the spots as you can. Turn off the pool pump and spot treat the algae with chlorine tablets then pour an all-purpose algaecide on the algae spots. Leave the pump off and let the algaecide work overnight. Restore water circulation the next day and brush off any dead algae and vacuum. Again, if it’s a heavy case of algae you may need to repeat the treatment again if there’s more algae remaining.
