This may seem a little rudimentary, but just to make sure I understand your pluming and flow set-up:
The airlifts obviously carries the water from the lower levels of your water collumn. Then it enters your sumps in the top and you just plumb it back to thetop of your tank from the bottom of the sumps, right?
Are you having to incorporate any bubble traps to reduce micro bubbles in the tank?
Otherwise, great props and kudos to you for an awesome system and for being so forthwright with all your information!
Thanks!