Cool, shrimp love live plants particularly moss. Most substrates work perfectly fine with shrimp and I've used sand, gravel, and EcoComplete and they've done well. However in terms of very specific substrates I like ADA Aquasoil and UP Aqua Shrimp Sand as they both contain buffering abilities to bring ph and kh levels down for shrimp. Careful with the Aquasoil though as it does leech ammonia in the first few weeks and should not be used for shrimp until it has "aged' for at least a few weeks. For regular/common shrimp like RCS though I wouldn't worry about buffering your water or anything though -- they'll tend to breed no matter what.