>>20321036I keep them in plastic cups with media (to gut-load the flies) and some surface material (excelsior) for them to pupate on. Stick on a lid and they'll multiply by the thousands.
You can rinse and repeat for infinite flies, but eventually you're either going to forget, or they'll crash and suddenly die out.
Leaving a rotten apple like that doesn't sound like a good idea, best just breeding them yourself and putting them in manually.
I don't really bother with purified water, the internet/frog community goes mental over it, saying that it can kill your frogs. I use the same water as I use for my aquarium, my frogs are plump and healthy.
Whatever water you're going to use, just leave it in a bucket and let it stand over-night, then it will be fine to use.
