Cleanup Crew in 40 Gal Breeder?

I recently had to move my entire setup into a new 40 gal breeder because of tank leakage. I moved everything very quickly and my water levels are fine, everything seems to be as if nothing happened. Problem is that I have a bunch of leftover food on the sand and I only have a few nassarius snails and they're doing a shotty job as it is. I do overfeed but my clowns and damsels won't eat it if it isn't falling so once it passes them, they don't pick it off the sand. This makes me feel like they're not getting enough to eat. Anyways, I was wondering what would be a good addition to my cleanup crew in a 40 gal? Sand bed is.. Oh idk, about 2-3.5". (It's not even)

I really want something that is very mobile and will eat a lot.