For the past 2 1/2 months, this tank has given me one heck of a lesson in humility. Things seem to be on the mend, but only after killing the majority of my sps.
I ended up losing a mystery green bottlebrush and pink birdsnest from C&C, green slimer and beautiful Cali tort from TECO, over 90% of my monti cap and digitata, and nearly lost some encrusting montis as well.
All the while I was desperately trying to figure out what was wrong. I lowered light levels, added flow, ran polyfilter.
I slowly and carefully adjusted temperature, alk levels, nitrate and phosphate levels using vinegar and GFO.
Never once did I question the belief that had somehow slipped into my head, the idea that control of the main elements (alk, cal, mag) and nutrients (nitrate and phosphate) made water changes all but unnecessary
When I finally threw my hands up in the air, stopped messing with my dosing pump and started changing water like a maniac, the results were immediate, polyp extension like I hadn't seen in months and LPS that I had assumed to be unaffected puffing to double their size, and a big serving of humble pie.