pH Down

Many types of algae can not handle acidic conditions.  If the pH is maintained between 6.5 and 7.0 it will harm the algae without hurting fish or plants.   This is especially effective against string algae and smooth coating algae Warning: Care must be taken, if the pH is dropped below 6.5 it will begin to harm the good bacteria causing the ecosystem to 'crash'.   Dosage:  1 cup per 500 gallons will bring St. Louis water down to 7.0.   Dosage will vary based on initial pH of tap water in your area.