Check out my thread. I rebuilt the UC design and thew out the air pump, stones and lines, replacing them with a simple water manifold to deliver a waterfall to each tubsite.
The 'epicenter' goes away, replaced by a control bucket where the pump and water cooling coil reside. Cooling your RDWC water to below 66f is critical to the success of the approach, IME.
Instead of merely pumping water to another bucket- where UC don't want you to put plants?!- it feeds a manifold which delivers RDWC water to half inch elbow fittings in the lids of every tubsite. For my manifold I went to home depot and bought 1" irrigation fittings called funnypipe tees.