How often to recalibrate pH probes?

[anthonymckay]

How often do you guys calibrate pH probes? My Alkatronic suggests every 8 months, but the Hydros controller suggested every 3. It's been 90 days since I setup my hydros, so I calibrated both probes today and was surprised at how far the readings had drifted... both were off by about 0.2-0.3. Usually my pH reading ranges from 8.2-8.4 in a 24hr period. After calibrating I was surprised to see it drop down to 7.95.

 

[Randy Holmes-Farley]

The answer will depend on your tolerance for drift, and how fast your system drifts. Mine did not drift over months, but I hade a different meter and probe.

A high end analytical lab will calibrate multiple times a day.

I'd suggest starting at 1 month, and if it changes more than your tolerance for error, do it more frequently.

Always recalibrate after a power failure.

 

[Dan_P]

How often do you guys calibrate pH probes? My Alkatronic suggests every 8 months, but the Hydros controller suggested every 3. It's been 90 days since I setup my hydros, so I calibrated both probes today and was surprised at how far the readings had drifted... both were off by about 0.2-0.3. Usually my pH reading ranges from 8.2-8.4 in a 24hr period. After calibrating I was surprised to see it drop down to 7.95.

I am surprised that pH readings are anywhere close to reality given how fast biofilms grow on surfaces and crud accumulates in a saltwater aquarium.

 

[gbroadbridge]

How often do you guys calibrate pH probes? My Alkatronic suggests every 8 months, but the Hydros controller suggested every 3. It's been 90 days since I setup my hydros, so I calibrated both probes today and was surprised at how far the readings had drifted... both were off by about 0.2-0.3. Usually my pH reading ranges from 8.2-8.4 in a 24hr period. After calibrating I was surprised to see it drop down to 7.95.

Mine get cleaned and recalibrated each month.