I had a FOWLR tank a while back that was neglected for a little while and the nitrates went up to 50ppm. There was an outbreak of hair algae so I decided to add a few turbo snails from my other tank for a while to clean it up. It's hard to describe a snail not doing so hot but I could just tell they weren't happy. So a day or two later I put them back in the other tank and they were fine. params of the two tanks were identical except for pH was 8.3 in one and 8.1 in the other and of course the nitrates in one tank was zero and the other tank was 50ppm. So I'm just wondering what level nitrates are dangerous to snails?