Hands down the best piece of equipment for me has been a CO2 scrubber. Can't imagine ever running another reef tank without it and for the life of me can't understand why this piece of equipment is not part of the "essential" must have gear. View attachment 2040862
Not essential because it just really is not something that many(maybe most) reef tanks would benefit from. In a scenario where it is needed it can work wonders (though expensive replacement media), but unless people have PH issues it is really wasted money in my opinion. Personally my PH is fine with my skimmer airline ran to outside air.