I cleaned the Hydor Pro 350 back in October, and August for the Magnum 350. You can see I have not cleaned front glass for awhile. After loosing almost all my snails, starfish, I also had a hermit crab stowaway I have not seen recently...the Cyanobacteria is half inch to almost the full depth of the sand. Will do water change in next week after sand comes in for 29 GSP tank. Wish someone would buy me RODI system for Christmas. Lost a Scarlet Skunk Shrimp over the summer. One of the three Azure Damsels that survived is half the size of the others and thus being picked on by the other two. It is now separated again.