Personally, I wouldn't bother with the airpump unless you are having issues with PH, otherwise you'll just end up with loads of microbubbles in the aquarium and it just looks messy.
From the picture of the boxes, it looks like they have their own venturi system. Air will be sucked in through the tube that comes out of the water. If you wanted to connect an airpump to them, simply remove the venturi airpipe from the outlet nozzle and replace it with the hose from your airpump.
if detritus is allowed to accumulate in a UGF, they become nitrate factories. Painstaking vaccuming is required to properly manage one longterm. People kept reefs quite successfully (especially back in the '70s-90s) with UGFs for filtration, but they also had to maintain them a lot.