Dual pH probe woes

[akopley]

I’m pulling my hair out right now. I added a second lab grade ph probe to my apex classic. I decided to go ahead and recalibrate both probes off of 7 and 10 solution. Each got their own new bags and I wiped them down between settling.

Both probes read correctly inside the solution bags even post calibration But both have significantly different readings in the tank (tried same location and separate areas). One is at 8.23 (up from what normally would be 8.1 prior to recalibration) and the new probe is at 7.8.

Now here’s the kicker and likely a coincidence. I switched the ports just now on the two probes and now they’re within .02 of each other...what’s happening?

 

[Ranjib]

It is possible. These probes are very sensitive to electrical interferance and other aberration caused by either environment or their housing itself. I dont know whats exactly going on there. .. but this can happen. I wont recommend chasing a number other than just being familiar with your daily pH swing and consider it in your overall tanks's chemistry strategy (like for sps you may shoot for higher ph and higher alk). But if you are serious about accurate pH readings, I'll recomemend doing calibration as well as running positive /negative controls. I myself face persistent issue with anomalous pH reading from atlas scientific probes, even after doing repeated calibration and temperature correction. I think we still have to innovate a lot to make things better and more robust

 

[akopley]

They seem to both be reacting to swings equally just starting from a different baseline.

 

[ChrisW]

Prob a stupid question but why would there be a need for two pH probes? Just got a controller so totally new with all this

 

[akopley]

Prob a stupid question but why would there be a need for two pH probes? Just got a controller so totally new with all this

One will be for the calcium reactor to measure the effluent.

 

[n2585722]

If one is brand new then leave it in the tank for a couple of weeks and then recalibrate. Even then they will not match exactly.

 

[akopley]

If one is brand new then leave it in the tank for a couple of weeks and then recalibrate. Even then they will not match exactly.

I read that as well. Kind of frustrating since I was hoping to use the probe to accurately set my effluent ph. I had no clue the variance as I have never used more than one ph probe.

 

[n2585722]

I read that as well. Kind of frustrating since I was hoping to use the probe to accurately set my effluent ph. I had no clue the variance as I have never used more than one ph probe.

Give it a couple of weeks. You can still use it just go slow in setting you set point. I would lower it slowly.