Dead Snail Problem Revisited

[Beverly]

We have had a problem with something (or somethings) killing snails in our 120g. A week or so ago, we removed about a third of the rock we suspected contained the snail killers, bathed it for two hours in 3 parts kalk/RO and two parts tank water, then placed it in a 20g with normal SW. Have kept two dead snails in the 120g and have closely monitored if these snails were disturbed in any way.

We have placed one rock at a time from the 20g into the 120g to see if more snails were killed or if the two dead snails have been disturbed. So far, we have found two rocks with bad guys in them, even after the kalk/ro and tankwater bath , and have segregated them in a 10g. Our house is in total disarray with tanks all over, and with the 120g half torn down. I'm so anal, that this mess is getting on my nerves

Anyway, we know for sure that these two rocks are harbouring bad guys, though we do not know exactly what kind they are. I am at the point of wanting to get rid of the bad guys at any expense, but cannot find the holes where they live Am thinking of killing the two rocks, recuring them, then eventually putting them back into the 120g. I have three ideas for killing the rock and the predatory inhabitants:

1. Boiling the rock for 20 minutes.
2. Baking the rock at 200F for an hour.
3. Putting the rock in RO water for a day or so.

Am asking for advice as to which method would be most effective, least messy, as well as so we might actually see what predators we've been up against. I'm thinking that soaking the rock in RO would fulfill these requirements.

Comments, suggestions, warnings, whatever are welcome . TIA