I was considering making my next one of plastic media packed into a plastic cage mesh cylinder, as i have lots of extra plastic media I used in a packed column, but VanGorder warned me not to. He said it's been done and eventually the drag gets to much and things fall apart including a motor burn out if you use a motor.
I was going to try that one except with plastic beads, then I thought bio-balls. I could not convince myself it would work. Now I have a bunch of plastic beads and bio-balls that I have been sitting on for the past 10 years
JKB,
I know I posted this on the Aquaponics site but I thought I would add it here for the benefit of others. It's basically a response to my email about building an RBC made of media vs. the plates: (From Steven VanGorder author of the book Small Scale Aquaculture).
What you are considering has been tried often in the past. In fact, a drum filled with high-surface area material was designed back in the 60's for the sewage treatment industry. And Dr. Timmons from Cornell, and Losordo from NC State built an rbc from spools of plastic material banded together. Lots of surface area, but all of these designs had one problem. They greatly increased the drag through the water. It was completely impossible to rotate the units using a waterwheel ... just too much resistence. And in every case that I'm aware of, the mechanical problems quickly developed. The gears on the motors stripped, the pillow blocks wore out, and finally, whatever methods were used to bind or enclose the media always failed.
This is similar to what happened when we were first developing the small rbc's. We didn't like to have to waste the fiberglass by cutting the plates into circles, so we built units with square plates. Of course, we tried rotating them without a motor but had to go back to it, but we ended up with a pretty nice design. But within a single season, the units just deteriorated.
Sorry. Hope this helps.
I thought you might enjoy a medley of photos showing much of this evolution of design that we went through. Unfortunately, the failures by Virginia Tech, Cornell and NC State left them all with the idea that the rbc's just weren't appropriate for commercial aquaculture. And I've had a difficult time trying to convince them and others that they are. And as you can see in the photos, we certainly had the chance to test them at an industrial-scale.
Steve
If pigs could fly bacon would be harder to come by and there would be a lot of damaged trees.
