Pondmaster AP100. Big fan of these pumps. I have 3 of them here. Unfortunately they need rebuilt every year cause the diaphragms tear but rebuild kits are like 10$ and a half hour to do. Price you have to pay to get specs of a $500-600 air pump for well under $200.
On my big system the reactor is a 90 gallon aquarium which has 3 of the 10" black rubber diffusers mounted into the bottom of the tank. Pluming goes through he bottom of the tank to 3 valves to control air to the diffusers. I tried running the whole system with a single AP100 but now use a coral life luft pump to run the tanks diffusers then just run the whole AP 100 on the reactor. Seems once you add bio chips to K1 it gets a little difficult to keep a good boil going, it takes a decent amount of air.
I haven't decided on an inner cylinder. Was thinking something like you did, would like to find something with a cone shape but we will see what I can come up with.
Do you think that piping will work ok? Should I just stick with 2 2" pipes going into the rfs? Might get a little more flow out of it or should this work ok?
I'd personally use single 3" going in..... Easier to center and would think it less turbulant.
I could see where the outer container being cone shaped could help, but not sure if I understand where a cone shape would be beneficial on the inside cylinder? Can you explain in a little more detail?