I put Sparkles in his own 2 gal on Sunday. Coming home from work today I found him with a big bubble nest and cloudy water. Water change was not scheduled until tomorrow, but I did it before dinner, it was that bad. The water smelled kind of like rotten eggs, and the cause seemed to be the little bridge ornament made by TopFin. I went ahead and soaked everything in very hot water for 10 min with a large dose of salt. Hope that did the trick. Issy's tank was Ok so his water gets changed tomorrrow. I remember having read a thread in which somebody else complained about this same problem but I can't find it. Can this be a coincidence?