My first guess would be the system is nitrogen limited. .08 no3 is low, which can be fine, but not if you have a low fish load and feeding. If pale acros are a trend it is likely nitrogen deficiency, add fish, add nitrate, daily dose ammonium bicarbonate…. and a little reef roids bumping up po4 from time to time will help. This would likely fix the issue fast.
Secondly, you didn’t mention low iron and manganese on your ICP but I’m sure it is. Everyone’s is lol. Daily additions will help corals gain zoox and improve health.
Last but not least, if that’s the only problem child, it could very well be bugs. White, black, red etc. check in the dark with a flash light to see if anything crawling on it.
Getting it into lower light temporarily will
Help darken it up if it indeed nutrient related.
That’s all I got! Good luck!