Hey, welcome. I use kessils. I'm using the dongal and programmed them on my phone. I used the knobs for awhile before the dongal came out. I have a 210 mixed reef. With three a360x and four T5s. But you got more than enough power for Lps and softies. I'd say intensity at 50 percent and 20 percent white. Start there. If they look small and shrunk up that's too much light. If they are expanding out need more light. Make small adjustments. Usually they will adjust to your lights.
That said lighting is probably not the reason your corals are not growing. Lots of things can stunt growth. Poor water quality, lack of nutrients, low trace elements, low alkalinity, temperature too low, salinity low.