Ok so I hooked up my apex el last night did the calibration with the 7.0 and the 10.0 fluid that it came with. I just got an alert that my ph is at 8.52!! So I grabbed my dads Hanna ph checker but it reads 8.2. And I tested it in the sump were my ph probe is at. Now my question is can i calibrate the probe using 4.0 fluid and 7.0?