I want to get a nozzle that will squirt water around near the substrate to keep down the mulm bild-up. I have never used anything but bubble up and hang on filters, so don't know anything about power heads, connections, nozzles, etc - where to get, what kind to get, should the power head be inside the tank and submerged or outside, etc? Anyone experienced who can summarize how to get something going in this area?