Back in April, two or three weeks prior to the public unveiling of the UAS test, I posed a simple question. In essence, would applying bubbles or Co2 to a waterfall screen reduce or eliminate the Alkalinity depletion evident in some scrubber systems, full text here; http://algaescrubber.net/forums/showthread.php?1838-Co2-turbo. Upon the UAS unveiling I decided to implement my ideas on my screen. Details of my tank etc are here; http://algaescrubber.net/forums/showthread.php?1823-howdy-from-the-uk-day-one Cutting through the history of the threads, I think that bubbles on a waterfall screen creates a better environment for the screen and hence our displays, and the screens ability to perform. Several benefits are; Increased Co2 consumption as opposed to carbonate/ bicarbonate conversion, reducing wasted energy, Introducing Co2 into the water column, replacing used Co2, creating a more natural display pH, Increasing oxygen concentration in ours of darkness, Reduced boundary layer thickness aiding gas exchange, Greater growth, hence filtering capability. There are a couple of benefits over the UAS, these being; Higher light intensities, Higher water flow, Smaller bubbles, increasing surface area and gas exchange, Vastly reduced boundary layer, No glass cleaning. The best thing about this improvement is that it's nearly free of cost.