I built a Reactor for my Rio 600 RVT and I'm thinking of using plastic scrubbies for Bio Balls. They should provide good turbulence, the downside is they might provide too much flow restriction and will likely accumulate sludge. The Reactor has a couple of cleanout plugs for maintenance, but it will be another cleaning chore. Although I had to put a prefilter (media bag) on the 600 as an Oto wedged itself in the input. I might upgrade to the 800 to get better chopping and a little more flow;I'll see how it blows. I'm going to use an SCWD for the return, but the plumbing isn't done yet.