Atlas ph probe calibration

[sfgabe]

My last pH probe broke during a move so I got a new one, but until then never had any problems. I've had the new one calibrated and running for about two months and then it started to drift upwards.

This past week it drifted all the way to 9, which I hope was about 0.5 off. I did a 50% water change to quell the panic and recalibrated yesterday. Today I get this, all the way to 9.5. I did a manual color test and got about 8.2.

I'm going to do a reboot now and recalibrate again, but any clue about the cause? Did I get a bum probe? How is Atlas about replacements? Seriously heart attack inducing here.

 

[Sral]

My last pH probe broke during a move so I got a new one, but until then never had any problems. I've had the new one calibrated and running for about two months and then it started to drift upwards.

This past week it drifted all the way to 9, which I hope was about 0.5 off. I did a 50% water change to quell the panic and recalibrated yesterday. Today I get this, all the way to 9.5. I did a manual color test and got about 8.2.

I'm going to do a reboot now and recalibrate again, but any clue about the cause? Did I get a bum probe? How is Atlas about replacements? Seriously heart attack inducing here.

Sadly I can’t provide you with experience, yet.
I can say that this sounds way too fast a change for normal operation. Typically calibration intervals I have read were once a month, I think.

Suggests to me that the reference fluid in your pH probe is going bad. I that dries out or ages in general, it gets influenced by your tank water, it changes the point of reference, e.g. 0mV or 7pH.

In your case I would assume that the change goes up, since the fluid gets influenced by your 8.2pH, shifting the „7pH / 0mV“ point upwards. Normally that’s so slow enough that you shouldn’t notice it this badly though.

 

[sfgabe]

It's a new probe so if it's a reference fluid error it's time to contact Atlas. The last one I had was the same model and I calibrated it maybe once a year.

I did a reef-pi reboot right after this post and it drifted all the way to 11 overnight!

It may be a bad cord attachment (or electrical interference?) because I pulled the whole thing, straightened it out, and ran it into the sump in a slightly different way. Then I recalibrated again, making sure to leave it in the calibration solution for a few minutes at a time. It's been OK after doing that but only time will tell.

 

[Sral]

It's a new probe so if it's a reference fluid error it's time to contact Atlas. The last one I had was the same model and I calibrated it maybe once a year.

I did a reef-pi reboot right after this post and it drifted all the way to 11 overnight!

It may be a bad cord attachment (or electrical interference?) because I pulled the whole thing, straightened it out, and ran it into the sump in a slightly different way. Then I recalibrated again, making sure to leave it in the calibration solution for a few minutes at a time. It's been OK after doing that but only time will tell.

I would not expect the connection to make that much of a difference, though I might be wrong on that. A broken cable might, but a bad connection should at most add an offset, not that amount of drift in my imagination.
The probe and the sensor itself are very (very !) high impedance, so in order to make a difference, the connection should need to be close to not connected to be comparable in impedance.
In my understanding Interference would add noise, not a drift or offset, unless your tank or your circuit charges up very slowly and thereby acquires a voltage.
You could test this with a multimeter measuring the DC voltage between tank water and ReefPi circuit ground.
If that is very high, you might think about grounding either your tank or circuit, depending on which is charging up.

 

[Sral]

BTW, if you try grounding your circuit, I‘d personally be so paranoid to use something like a 50k resistor in the connection. That limits the current from a 200V source to below 10mA, which should not grill anything.

 

[Sral]

BTW, if you try grounding your circuit, I‘d personally be so paranoid to use something like a 50k resistor in the connection. That limits the current from a 200V source to below 10mA, which should not grill anything.

Thinking about it, the same goes for the tank. Don’t want any inhabitants (or yourself) grilled or made uncomfortable

 

[Snoopy 67]

Personally never heard of Atlas.
I use Milwaukee probes.

Milwaukee MA911B/2 pH Electrode/Probe/Sensor | Premium Aquatics

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[Sral]

Personally never heard of Atlas.
I use Milwaukee probes.

Milwaukee MA911B/2 pH Electrode/Probe/Sensor | Premium Aquatics

Aquarium & Fish Supplies Superstore. Guaranteed Low Prices. Free Shipping for qualified orders. Aquarium supply for your aquarium fish, saltwater aquariums, freshwater aquariums and ponds. The best aquarium lighting, protein skimmers, aquarium chillers, calcium reactors, aquarium pumps for fish...

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Thanks ! I‘m pretty sure that the probes themselves are completely compatible, so one could use a Milwaukee probe with an atlas sensor board without problems.

Atlas Instruments is a go-to choice for the sensor board, because it has a digital interface that is easily connected to a DIY controller.