Which calibration fluid should I use 4 or 10?

[empireinc00]

When you calibration your PH probe to measure/control PH level in the calcium reactor, do you use calibration fluid 7 and 4 or 7 and 10? I have been using 7 and 4 all along. I just had funny feeling if I might be wrong. Please help me out here. Thank guys.

[reefhobbyguy]

If you are measuring your effluent from your reactor, it is less than pH of 7 so you would want to calibrate between 4 and 7.

If you were measuring your tank ph, it is higher than 7 so you would calibrate between 7 and 10.

[empireinc00]

Thank you.