HTH, 32OZ, Super Algae Guard, Extra Strength 60% Algaecide, Prevents Algae Growth In Pools Without Foaming. Active ingredient-Quaternary Ammonium Compounds 28-32 %. HTH® super algae guard 60 is an effective, non-foaming algaecide product that, when used regularly, will prevent and kill green, black and yellow algae.