This is my dilemma. I really don't want to spend the money on a RO/DI unit as I have a small reef tank. My LFS which is reputable sells premix at .89 a gallon. Once a month....15 gallon change....Do the math ....salt...two days waiting.... temperature change....It seems to me I would be better off just buying the premix. Buy the way they use Instant Ocean salts and everythings on par with what I've been running. I do like the Kent salt better but for the hassle?