Dwell time, or contact time, is greater in a venturi skimmer due to the random motion of the bubbles. Once in the neck is no longer skimming dwell time as the bubbles have done their job. And you cannot find any tall NW skimmers, can't do it without very costly pumps and all public aquarium displays still use venturi skimmers because you can make them tall.
Once a NW wet bubbles enter the neck they don't rise on their own. Bubbles reaching the surface don't go up any higher without all the other bubbles pushing them up the neck, and this does have dwell time, not good. During their slow movement to the top the proteins and solids fall back into the skimmer to get picked up again, and again, and again, and some of the solids collect in the skimmer body which is one reason nitrates are higher than in an aquarium using a venturi skimmer. In a venturi skimmer with all those different size bubbles any bubble larger than another moves up the neck, all the way to the top. This skimmate gets put into the cup faster and NO solids cake up inside the skimmer body. This is why early venturi skimmers never needed to come apart. The first skimmer ever to have a take-apart flange assembly was the downdraft, and it required disassembly to clean the long body because your arm wasn't long enough.
The ONLY difference between a true venturi skimmer and a NW is the size of the bubbles. All else is just bubbles in water inside a tube. But those difference in bubble sizes says it all when it comes to performance, contact time, faster skimmate/protein/solids removal.
The reason for the BUBBLE PLATE is to stop the turbulence because those tiny bubbles cannot tolerate much and would be pushed out of the skimmer. So, they must put those tiny bubbles into a calm column of water, and those bubbles are transported upwards as fast as possible, not good for contact time./
ALL skimmers work, and it isn't a skimmer design that produces a good foam, it is the water surface tension. You pump bubbles in, the water foams or doesn't foam, and you collect what you get. The real performance increases come when you keep those bubbles in the water for as long as possible and why larger aquariums require taller protein skimmers.
Any NW company that used to make tall skimmers (anything over 30") had them sized for larger aquariums too. When they discovered they could no longer make tall skimmers they now say their shorty skimmers can do the same capacity aquariums, I have doubts on this. Oh it will skim, but likely not be able to keep up with the proteins being produced by those larger aquariums.
All said, I'll never make a NW skimmer, I can't do that to my customers and why I never even considered making them when they first came out.
Finally, all skimmers work but why buy one when you have to buy their costly pump IF it is still made, or an entirely new skimmer that has a proprietary pump when a true venturi skimmer can use any water pump and will last a lifetime?
