Nice tutorial! I think I've only seen 2 other builds I liked that had decent setups. One was a vortex setup but I didn't save the link and no longer seem to be able to locate it. So I will just take a seat right here!
Not exactly sure how many gallons this cuts out? It's about 2" less than the total volume, and I don't know how to equate that? The the 2" uniseals are only 3.99 retail and you'd only need one.
The vortex is really of very little consequence. It is the airlift which increases the dissolved oxygen and having a cone bottom tank ensures a thorough mix.
MM - Have you noticed an increased amount of dissolved O2 when you raise your riser pipe in an air lift system? On my 55 gal brewer, I made it so it lifts the water a good foot above the water level. I was hoping this would increase the dissolved oxygen compared to 6'' above water level. I need a meter.....