dKH between 6.5 and 7.5 seems to work well with ULNS. I personally keep 7.5 now with better results. Ca 420-430 ppm. Corals are doing better now for me. I am starting to dose some ZeoVit products as well but still primarily Brightwell's. I have also found pH is not that important as long as it is above 7.8 most of the time. Mine averages 7.85 these days with no adverse effects I am aware of.
From your params, you are basically running a low nutrient system, your Ca and ALK are too high IMO, yours corals may be handling it ATM but are stressed to some degree, even if they are growing. All it will take is another added stress factor and you could see issues begin to happen.
Your SG is a bit low but shouldn't cause you any problems, I like to keep mine 1.024-1.025. SG is really livestock dependant, I posted a chart detailing the SG throughout Indonesia a while back. Since many corals we have in or reefs are from this region I thought it interesting to see the abundance of FW runoff throughout the islands can bring the SG quite low in some areas. Because we often have corals from various regions of the world with higher SG, I tend to go with an average SG for my tank as I do with temp.