add some live daphnia ?
Diatomaceous Earth is very small sharp porous shells from dead diatoms. It is effective as a non-poisonous ant control method because it gets trapped in the ants exoskeleton joints. In 10 years of using DE filters I can assure you it has no affect on snails or bottom feeders like catfish! I have never kept shrimp though. My hunch is it would not be a problem for aqueous shrimp but that is just my guess.DE is bad for ants and other bugs that crawl... so I'd worry about using it in a tank with shrimp and snails.