So you just drop boiled zucchini in there? it doesn't mess with the water quality?
Well, you don't just drop a week's worth in there. You put a little chunk, the algae eaters and snails feast for some hours, then you remove the leftovers and then you don't feed them again for a long while. Sometimes I've left it in for over a day but that's a no-no.
And now that you mention it, the only tank I feed zucchini in is my dirty neglected tank filled with detritus, snails, a few fish, shrimp, ugly plants, yellowy water that I sometimes let get too low and it ALWAYS has great water quality with only a dinky sponge filter. My nice tank will sometimes crash and burn for no good reason. I think I'm going to put a sponge filter in that tank and get rid of the tetra whisper filter.
ETA
They should only eat plants if the plant is sick or dying.
Yeah, sometimes people see the snails at holes in the leaves and think the snails made holes, but usually it's just the plant deteriorating and the snails are cleaning up the dead stuff... like maggots!