For what it's worth, I didn't have much of a need to dose for about the first six months on our 75g; water changes (I do weekly) alone were enough to maintain everything in a solid range. Once consumption started exceeding what I was replenishing via the water changes, I started dosing. To that end, I've been dosing alkalinity and calcium every 90 minutes (so 16 times daily) and I spaced the two apart by five minutes. Some suggest a much longer period between the two but I've never had an issue (I dose close to my heaters and don't have any precipitation on them). It has worked well for me the past two years but there are many ways to skin the proverbial cat.