Before I moved I was using tap water with conditioners but last year when I moved I got my new r/o unit because the TDS count was off the chart and couldn't keep the algae down. Since then I have had problems keeping snails alive. The other day I removed another dead snail from the tank and his shell literaly fell apart in my hand! That's when it dawned on me (duh); with r/o water I'm also removing the MINERALS from the water and there is no longer any calcium for the snails to supplement their shells! when I tested the tank water sure enough my GH was around 54 ppm. What if anything do any of you use to supplement these minerals in you tanks?