Hi All, I`ve been in the hobby a while now. I have had good success with Softies and LPS but when it comes to SPS I just dont seem to be able to hit the sweet spot. Tank is a DD Reef-Pro 900 (290 Litres total system), I have a Radion XR15 (Blue) at 100% on the AB+ Setting, 10% water change every couple of weeks, good flow, 2 x AI Nero on random setting upto 85%. My parameter testing since Aug are below. My question is... do these results show a "swing" which is to broad to be comfortable for SPS or is that within a normal tolerance given testing accuracy etc. Date Mg KH Ca Phos pH Salinity Nitrate 11.06.22 1360 11.2 460 0.5 8.26 1.025 2.5 12.06.22 1440 9.5 450 0.03 8.35 1.025 3 18.06.22 1400 9 440 0.25 8.29 1.023 5 25.06.22 1360 10 450 0.03 8.1 1.025 2 16.07.22 1240 7.7 425 0.03 8.16 1.024 3 26.07.22 1360 9 425 0.03 8.3 1.024 5 06.08.22 1360 8.1 410 0.03 8.14 1.025 5 13.08.22 1400 7.8 450 0.03 8.2 1.026 2.5 24.08.22 1400 8.7 430 0.03 8.15 1.026 0.5 27.08.22 1440 9 450 0.03 8.2 1.027 0.5 10.09.22 1200 8.1 425 0.03 8.17 1.027 0.5 18.09.22 1440 7 410 0.03 8.16 1.025 0.5 24.09.22 1480 9.2 420 0.03 8.1 1.026 0.5 01.10.22 1440 8.4 450 0.03 8.2 1.027 0.5 16.10.22 1400 7.8 380 0.03 8.2 1.026 0.5 Very interested to hear others views on this...