One thing to bear in mind is that, because they achieve harmonic (wave) motion, the Vortech's effectively move a lot more water than they are rated at. The Resun controller is not capable of that, as it's not possible to set the switch period low enough (I would need about 1.5 s), nor to reverse the motor. I'm sure some smart electronics boffins could build one that could, but I'm not a smart boffin. I'm starting to wonder whether the Vortech's don't actually represent a cheap option - and believe me, I'm firmly in the Redneck camp - I hate paying inflated prices, but there may be a good point to be made here.
Take my 1000 litre tank. I'd like 80-100 x water turnover - that's a whole lot of (non-harmonic) pumps. Here's what the Resun's give you:
Wave information
Small: Power 6.5W / Qmax. 2000 l/h 530 gph / Adjustable Duration 10-20s
Medium: Power 12.5W / Qmax. 8000 l/h 2116 gph / Adjustable Duration 5-15s
Large: Power 25W / Qmax. 15000 l/h 3968 gph / Adjustable Duration 2-10s
So that means that at maximum setting (min small, min medium, max large) you effectively get 8400 l/hr. And that's if you believe the ratings. So I'll need about 10 Resun's to get an 80x turnover, costing about R6,000, at least.
Otherwise I can buy 2 x Vortech's, for R8,000. I've never used a Vortech, but looking at the video's on youtube, and using a bit of wave theory, it seems quite possible that the 2x Vortechs will give a much better effective flow than the 10 x Resuns. And the Resun controllers will definitely pack up regularly (my personal experience, and reading on Reef Central), so those would need to be replaced with something more reliable, at some expense and hassle.
I think I'm gonna splash out on a pair of Vortech's.
Q