Green water is single cell algaes.. when you get it in your tank, it's called an algae bloom and nobody wants it.
I buy lab cultured disks of pure Japanese chlorella and culture it. Grows in either fresh or salt water, one of the few that does this. Very tiny cells, so good food for filter feeders.
You can also dissolve bread yeast in water and feed that to filter feeders like Moina, daphnia, seed shrimp, copepods possibly too. I feed yeast to the seed shrimp I have, [ ostracods], and fry food to the Dero worms now and then. A bit of algae tab or fish food for the snails, not too often. So far, so good. If you can't find these things live in a store, you can order them from Carolina Biological labs.
I can't get Dero worms from them, because it costs too much to get them to Canada. Some sort of inspection is needed, costs nearly $200... but I can get the other critters, live by mail order. The only live things my local stores have are the occasional flightless fruit fly, for frogs, but great for fish, and crickets, etc., for reptiles. I get them to feed my floating frogs.. hate crickets but the frogs like them.
Green water is the best food for filter feeders like daphnia and moina, but yeast is a very good second best.
Snails would likely eat the veggies, but spinach would be a lot better than cucumber I'd think. Boil it to soften it, they prefer it that way. Small pieces, don't let leftovers rot in the tank too long if they don't get eaten up.