Immediately Removes String Algae. Works On Contact. Money Back Guarantee. CrystalClear® AlgaeOff® utilizes the latest in oxygen technology to remove string algae quickly and efficiently. CrystalClear® AlgaeOff® is an EPA registered, granular algaecide that works in seconds, adds oxygen to the pond, removes odor and is the only water treatment product on the market with a money back guarantee. CrystalClear Algae-Off will help remove string algae from waterfalls, streams and rocks in seconds. Use the maintenance dosage of Algae-Off once a week and eliminate complete pond shut down for yearly clean-outs forever. Algae-Off will also keep fountain intakes clean and remove unsightly scum and algae from the perimeter of any size pond.