Isn’t it rather difficult to get O2 saturation over 100% in a reef tank? I know that photosynthesis can increase O2 saturation but with high flow and good surface aeration, it should be difficult to get much above 100% O2 saturation. Similarly, given skimmers, good flow, surface aeration, it should be difficult to get that much below normal O2 levels. Maybe not 100%, but relatively good levels of O2 saturation.