Let’s see some pics of this SPS tank of yours that you’ve got tuned to the T!Ppl I have a 120 and 40 gallon sump full of 40 yr old ocean live rock I do water changes maybe 2x a month and can grow SPS no problems have not tested the water in years I can see when it is not happy and do a water change. Only thing I put in tank besides food is esv 2 part and I feed once every other day. I have a purple Tang about 3c Inches bill Tang and fix face all about the same size the 5 other smaller fish. I run led's for lights run a small skimmer a ramora. No filter socks no "gadgets" at all water turn over is about 5 to 6 times an hour.