Potato to rid aquarium plants of pests in quarantine?

I've used potato to get rid of unwanted snails from tanks before. Take a big chunk lay it on the bottom, leave there for a day then remove. Replace with a fresh piece of potato everytyme, so you won't spoil the water. Any snails in the tank will gravitate towards the potato which you can then easily remove them. I've never heard of using a potato to release acids in the water column to rid of aquarium pests though. You should ask the person again to give you a better explanation of there method, and repost there answer if you could, I am curious- sounds kinda dangerous to the fishes health though to leave foods in the water for to long a tyme.