Ah! Yes! I already researched this post and when I get back home (late August this time out) I'll begin the tests. Meanwhile, I would like to find a supplier of the right coagulants, though what I have read so far makes me wary of using Aluminum Sulfate without learning a LOT more about it. As I posted, my fish are doing great, though our daughter just told me that she is noticing polywogs with legs dying, though the other smaller ones seem fine. Is dead polywogs indicative of anything serious? tnx