So i've been looking up online some different types of cleaning crews to help keep my tank squeaky clean , I know most problems start with water so I have been using RO water and am upgrading to a better skimmer but I would like to add more to the cleaning crew. I was thinking maybe a cucumber or nudibranchs along with more hermit crabs? I was checking out the sand sifting cucumber and the lettice nudibranch specifically but are there any problems with the cucumber depleting the sand like a sand sifting starfish would?