That is what I mean. If you have neos then it doesn't matter. Since they breed like rabbits, chances are you won't notice a few missing here and there. But if you have PRL and TB's which have low survival rates to begin with + this? I am afraid you'll only see 2-3 grow up to be adults per batch of off-springs
The sponge as a pre-filter for the canister I have tried before, but didn't like it at all since it clogs up way too fast. Need to clean it out every week and for a tank you don't want to disturb all the time (PRL / TB tanks), that is a lot. Every time you stick your hand in the tank, you risk parameter changes.