I have had many reef tanks with clean up crews. I am forgoing the coral this time in favor of fish. 180 gal. I plan on angels, butterflies, tangs... so I know they are mostly not safe for CUC's. what do FOWLR people do for their clean up crews? how to keep the substrate clean. I was thinking a blenny to clean the sand but beyond that all my past experience and options would get eaten (crabs and snails). suggestions?