cuc

Hi Everyone, I have the following CUC: Electric blu hermit Red leg Hermit Turbo Snail X 2 Fire shrimp And this guy? Think he is a Nassarus snail? My question is this. my DT volume is around 280L. Its 1500x500x448, How big should my CUC be? So far none of the CUC eat the left over pellets...