I'm with mwsmith2.... I had the problem with foam, then I took mwsmith's advice & forked out a little more $$$. I had mustard algae, & had used a total of 4 bottles of "algaecide" before I knew there was a difference in them. I bought 2 bottle of polyquat, & there was a HUGE difference the next morning. And, 2 days later, perfectly clear water.

HOORAY FOR POLYQUAT!!! I will never be a cheapy when it comes to algaecide again.