I have a yellow cucumber in my tank for almost 3 months now and got a very healthy population of nassarius snails and other CUC so far no problem, but my tank has a 1 1/2 inches sand bed. My tank is LPS and softies dominated, from Zoas to a wide variety of Leather Corals, Nems and few SPS. Because of that I run carbon in a reactor constantly to be in the safe side, leathers are notorious for releasing toxins and zoas also, If an Anemones dies it could nuke your tank as well. So running the reactor keeps me mind relaxed and it also helps maintain water clarity, so is a plus in my system setting. Also be aware of your fishes compatibility because some might nip and upset the cucumber and there is when the trouble comes. I think they are a nice addition as a bio diversity and they will deliver what they meant to be, sand sweepers and cleaners. In my personal opinion I will go for it, but I will took the prevention measures as carbon media 24/7 and inhabitants compatibility. Don't be afraid but play on the safe side of the game.