Best way to completely kill off snails
So II got my nieces and nephew a tank 2 Christmases ago. Its a community tank lightly stocked and has a few plants in it. Somehow they introduced pond snails into it. I added 2 assassin snails to try and control the population, but they are over matched. The substrate literally moves because of all the snails. My sister wants to start up a new tank for a couple of angel fish, so I'll have a holding tank for the current occupants of their 29 gallon. My question is, how do I kill all the snails and eggs without using copper. I keep shrimp and would like to be able to give them some culls eventually. Thus the reason for staying away from copper.
I know over feeding is part of their problem, and I am working with them to moderate their feeding.
Can we cycle the new tank, then transfer fish, and just leave the snail infested tank dry for a month? Could we reuse the substrate and lace rock after that, or am I looking at throwing everything away and starting over?