Did your vet give you any advice/tips on worms?

Soak him/her every day or every other day for 15-20 mins in luke warm water up to the bottom of his shell.

You can't really overdo soaking--I wouldn't really leave him in for an hour but if you leave him/her in for an extra 5 or 10 mins it won't hurt.

I fill up my sinks and tubs throw every one in for a weekly soak and do other things in the meantime, come back about 20 mins later and they are good to go.