Thanks a lot for the information. I read both sides of the debate. Not knowing which one to believe, I did add phyto, but only twice a week or so. And that's what I'm worried about - a contagious disease. Problems only started after adding this new clam that died so quickly. Grrrrr!!!! I hope my big maxima is okay. I'm doing a water change today or tomorrow, don't know if that will help.