With downdrafts the step transitions are harsh, but often then extend to a 1-2′ neck. Turbulence is reduced below in the box and transitions, but the foam head allowed to rise without obstruction or turbulence into an extended neck straight to the cup. NWs are a different animal, but some DDs such as the ETSS 1500 or the oldy-but-goody RDIII come to mind regarding the constant tube diameter.

As Mike pointed out, a cone is not the end all be all. Air draw must still be matched to the body and neck size.

Regarding skimmer comparisons… less air, less contact time. Observed so far: Less nutrients, less turbulence and less electric consumption. (All 3 pluses in my book )

I do believe the cone design is better than “traditional” skimmers. The real questions are how much better and does the improvement warrant the price? I am not sure these questions will ever be answered for any skimmer.

Lastly price. With molds becoming prevalent, if the trend continues cones will slowly become comparable in cost to cylindrical skimmers. Unfortunately this hobby cannot support the volume for significant R&D making early adoption expensive… but that’s what helps keep the hobby progressing.

This is one reason I went with ATB, as it seemed from the skimmer experts I spoke with that the Airstar was perfectly matched to its body size…I wonder how the Vertex cone with two RDs pulling 3600 lph will match to a smaller body than my L that pulls ~2100-2200 lph, and seems a perfect match to me.

Its no secret, cone are very difficult (and/or expensive) to make in a quality manner. However, to what end will this help? Would a constant diameter tube perform better?

It’s too early to make any calls, if any can be made… but I do believe there is something to the gentle reductions—the cone being the obvious epitome of this.

That said it’s a bit unfair to claim Deltec as a knock off. They are an innovator of the recirculating design and many skimmers should pay homage to the AP line.