The Red Sea ones are noisy and the aqua beat or whatever it's called app is kind of wonky. If you're going to be dosing slowly they are good. I guess they all depends on what you are planning to dose. If you have an apex I would just go for the DOS. DHL has a standalone unit that I've read is solid but don't have 1st hand use.I have one of the Kamoer XT pro and I'm very happy with it. The app is pretty smooth as well. Aquavitro Sentía is also another good choice and you can modulate them. And ofcourse the very popular and expensive ecotech versas.Thank you all for your fast replies..
Kamoer looks pretty good. Anyone used read sea ones?