- I have 2 other tanks, one is a 10l shrimp picotank and the other is a 35l low-tech planted tank with a betta
- there are snails in both other tanks; they show SOME shell deterioration but they don't look sick - they are active, they reproduce, they never burrow
- in light of the above I thought I'd summarize the things that the main tank has and the others don't have:
--- substrate (ADA AS New in main tank, other substrates in the others)
--- rocks (the main tank has, STRIKE THAT, had a couple of "Ryuoh" stones); I removed them while writing this post; see pic below for appearance; they don't scratch easily; they fizzle energetically in contact with vinegar
--- fertilization; I guess this could be a source for something toxic; I could buy a new batch from a totally differnt source (my original one was www.greenleafaquariums.com/ iirc)
Why did I not mention all these things from the beginning? Slow thinking I guess, sorry.
The stones (below, the wet ones, I just removed from the tank; above, dry, a stone from the same batch, it was removed from the tank a while ago: