No Mike it has nothing to do with it, if it is not broke do not fix it. It has to do with steady state levels 24/7, not messing around with 2-parts, which require more frequent water changes or larger water changes. This is due to the continuos increase of the components of the 2-part that just accumulate over time, that have little use, namely the Sodium from the buffer/ Alk sup and the chloride from the calcium sup. One needs to due at least a net gal WC of 30% / m to keep these in check. You do not get this from reactor media, as it is aragonite, CaCO3, no sodium or chloride.
Changing from a 12hr cycle to a 24hr will surely creat greater fluctuations as the Alk and Calcium will drop more in 24hrs than 12 hrs. In your calcium, for example, if you had say 420 ppm and 24 hrs later it drop to 400 ppm, that is 20 ppm drop the corals would see vs. 10 ppm drop in a 12 hr cycle. The calcium drop would have little effect but the Alk would have a greater impact, not only on coral growth but buffer tank water pH. On reefs you see pH and O2 sifts day to night but about zero on Alk none on calcium.
In short two parts are fine for smaller tanks or even larger tanks if they are not SPS dominated. Did you look at the cost effectiveness in the article of 2-parts vs reactor. If you are happy with you current set up that is fine. Your stated flucuations given 12hrs or if you went 24hrs are not going to be any big issue or should not be if you stay on top of things. It is basically just a choice for you, less costly better stability with a reactor or stay where you are at.
