Thanks, I'll increase the distilled water. I did have Petoskey stones in the tank which are made of calcite, I believe. I don't know if they were the culprit but I took them out. No other decor except for the mopani now. Maybe it is
all the Caltrate. I serve it on a reptile dish now instead of laying it on the gravel. Less mess now, but they still poop it out all over the tank. It's almost like sand when pooped out and does not suck up at all. I wish I understood the chemistry better.