I have a bucket of shock tabs (I don't think they're 3", I think a bit smaller) and a busket of 3" trichlor tabs. I think I'll keep the trichlor tabs around in case I need them for when I'm out of town for a few days, but can anyone forsee a situation that I would need the shock tabs? They're OK just sitting there, but if I'll never need them I'd rather give them away to someone who actually uses them.