However, having the UGF in place, should you notice problem areas forming in the Jaubert Plenum, allows you to instantly alleviate the problem should it occur. Most aquarists who do use UGF plates in place of the egg-crate diffusers, cap off the lift tubes completely. I recommend leaving the caps off and placing a small strainer over the tubes. If an area of the substrate should begin to go anaerobic the hydrogen gas released from the area may, hopefully, rise through the lift tubes creating a draw in the plenum allowing oxygen to get to the area of concern, killing the anaerobes. When anaerobic bacteria takes over, the risk to your aquarium is multiplied a thousand fold.
Anaerobic bacteria can be any one of the bad guys, like e-colli, botulism, etc.
Respectfully submitted, Gary V. Deutschmann, Sr.