Planted Tank Guru
Join Date: Jul 2010
Location: British Columbia, Canada
The quickest, easiest, least expensive, and most effective way I have found to eliminate blue-green algae is to dose plain household hydrogen peroxide (H2O2) at close range, using a plastic syringe or test kit pipette (with the filter off, and remaining off for at least a 1/2 hour after dosing). One dosing usually does the job, but a second dosing the following day is sometimes necessary.
Once that is done, one needs to remedy some of the main causes of BGA to prevent it's return - eliminating dead spots in the tank, improving oxygenation (water flow and movement), particularly in the lower areas of the tank, and improving tank cleansing routines (vacuuming, etc.) Add an air stone, power head, or water circulation pump, or a combination of these, do a good tank clean-up at substrate level, and continue to maintain a good level of tank cleanliness overall.