Alternating currents?

[pocilipora]

I have my PHs on appliance timmers. Used to be on a wavemaker but I didnt think it was neccesary. An hour or two on/off cycle is all thats needed IMO. But having a laminar or alternating flow does change the way a coral will grow and how strong its structure will be.
Ive used 802's for years. I was going through an impeller maybe once a year, longer on appliance timmers. Pro4s I wouldnt bother with IMO.