the old familiar brand [SEP] if you got a waterbed you gotta have algaecide this is the same brand i used starting in in my first waterbed the same we sold at the waterbed store where i worked in the and so it seems friendly and familiar my household has two waterbeds currently so it is nice to buy ten bottles at a time so we are covered for a few years i put a bottle in whenever i move and have to refill the beds and also about once a year have never had any algae problems