SPS struggles

[Drock169]

My 40 has lots of softies, some lps and the SPS are growing very well, theres no carbon running in it, just a really good skimmer, there is detectable nitrates, maybe around 1 or so, so I dont think you low nitrates are an issue. I dont test for PO4 but i'm sure theres some in there. I also doubt your Mg would be the issue. I do a water change maybe once a month.

I just try to keep it simple, Deltec mce-300, maxi-jet mod for flow, and a 250w halide, plus 5 or 6 fish i dont remember.

My question for you is, are all of the Sps being affected or just certain ones? Are they in the direct path of the flow?
As for vodka dosing, I dont recommend it, I experimented on my large tank when it was full of sps and it worked for a good while but I experienced most of the problems that VSV dosers experienced.