I see what Mega is saying on the one hand. I am not defending the Aqua C because I just spent $320 on it either. I told the owner/maker, in much nicer terms of course, if this thing sucks and isn't doing the job, he will be refunding me my money. But, for the application it needs to perform, it may be the best skimmer for it's size. Who knows? There are no standardized tests or benchmarks like CPUs that are recognized.
But, if contact time is the answer, neither ETS RD3, Aerofomaer 24" model or any other skimmer is really any better than the other for the same size. They all have short contact time in relation to a 6 foot tall skimmer. I think what the Aqua C and HSA/Aerofoamer/Bullet designs are trying to capitalize on is massive bubbles in a small chamber. There are too many different philosophies regarding skimmer designs. Most driven by making $$$. High flow through rates, slow flow through, maximum efficiency per bubble, maximum efficiency per volume, it goes on and on, you need a standard, and until their is a independent third party to analyze and rate the skimmers, we will sit here and ramble out theories on why brand X is the best. The fact is there is no such skimmer that performs the best for every application and situation out there.
That is exactly what the aerofoamer, HSA, Bullet and Aqua C are all doing for the small models. So contact time is going to suck on all of them. You can only get so much contact time out of a 24" skimmer and maximize every single bubble.
If you read Aqua-C web site, have you? You will read the philosophy of their design. For me it fit my situation, too small a space and that is the only one that would fit and do the job.
Well, my two cents. You have heard that saying: "Opinions are like a**holes, everyone has one and they all stink."
Keith