Tony
We use ESV two part product with water changes of 10%+ per week. We have been dosing the 2 part 1 time week at 1/10 of the labelled amount between water changes. Our parameters have been fairly stable KH between 9-10 with elos kit (~8 KH with API kit), CA around 440-480 with API test kit, salinity 1.026 with refractometer, PH 8.2-8.3 with hand held meter for the past few months. We are using IO salt with RO/DI source water. We started having good Coralline growth once we added Phosphate reactor, skimmer and starting using RO/DI water for our 55g ( I am having hard time keeping up with the growth). On the nano 24g the coraline growth is not as good but I beleive that is do to the skimmer on that system is not very effective and do not have as good phosphate control (don't have a reactor just use the bag in one of the chambers), phosphate levels are around 0.2 -0.4 ppm where as for the 55g they are not detected.
In reading up on the 3 part product they recommend a KH of 7. However we have found in our system if we let kh at or below 7 our zoos don't open but when were run around 9-10 corals and zoos appear to be doing okay.
Mike