Ph probe drift upwards

rob safron · Nov 21, 2018

I have 2 ph probes running via apex. Every single time I calibrate them, my tank ph drops by at least 0.1, sometimes a little more. Then over the next couple weeks it drifts back up that 0.1. After cal I check them in solution and they are close, maybe not exact to the 7.0 and 10.0 solutions. Do i assume the ph in the tank is only correct for the first few days or is it normal for ph probes to take some time to read aquarium ph correctly. I will say both ph probes trend exactly the same at the same time.

NY_Caveman · Nov 22, 2018

rob safron said:
I have 2 ph probes running via apex. Every single time I calibrate them, my tank ph drops by at least 0.1, sometimes a little more. Then over the next couple weeks it drifts back up that 0.1. After cal I check them in solution and they are close, maybe not exact to the 7.0 and 10.0 solutions. Do i assume the ph in the tank is only correct for the first few days or is it normal for ph probes to take some time to read aquarium ph correctly. I will say both ph probes trend exactly the same at the same time.

I have no Apex, but most experienced that I have read seem to indicate the pH probes are not super reliable. I have seen folks recommend replacing them after 6 months as well. Luckily, a 0.1 pH drift is not too bad considering some tanks can fluctuate 0.5 pH in a single day between night and day.

rob safron · Nov 22, 2018

Most will say they are way more accurate than test kits. My kits always show higher than the probes. My day and night swings are big. After the cal goes 7.75 to 8.1 and prior to this cal 7.87 to 8.18. Frustrating but all in all tank seems to be doing well, have to switch to reactor as I’m dosing 400 mls/day so not worried. Just wondering if the correct number is right after cal or after it’s been in the tank a while.

WWIII · Nov 22, 2018

You could check them in the calibration soutions after a few weeks to see how close or far off they are. It seems these probes need calibration every 6 to 8 weeks. I guess it's better than testing each day and it is reading 24/7!