Backyard Aquaponics
A place to discuss aquaponics

Hey guys I splashed out and got a ph pen with seperate probe the other day.

Got some 4 and 7 buffer solution and calibrated it. (Realized later that this particular model wants 6.86ph not 7, but hopefully that's not an issue?)

My question is, when I put the probe in the calibration solution the sensor is super quick to respond, within a few seconds.

But when I place it into my FT, it takes almost a minute to slowly creep up to an accurate reading.

Is that normal? I tried recalibration but same thing again. Just curious if I have a dead probe or sensor or if I'm just impatient...

Thanks guys, wasn't sure who I could ask

My tester typically takes about a minute to settle on a value- that's normal. That's for the standard buffer calibration solutions and the FT water. I'm not sure why yours would change so quickly in your standard solutions.

Yeah I have a Milwaukee 600 pH "pen." I don;t trust it. It's slow to read and doesn't seem to give accurate readings all the time. I want it to work, but I find myself using the API testkit for a "real" reading.

I thought maybe it's because I let the probe dry out a few times and it oxidized or something. Does anyone know if this is a thing? It's dry when you get it, and you need to soak it for 5 minutes or something. So I figured if it dries out I will just soak it again.

It would be really handy if it gave reliable readings all the time, but I often find it doesn't match the API method, by a large margin, even if I calibrate it. I can't trust the lives of my fish and plants to it.

Yes, once your probe dries out it needs to be soaked in either pH7 buffer solution or probe storage solution to rehydrate. I'm not sure if doing this over and over is likely to be a problem or not, but I keep mine in storage solution all the time, and find I need to replace the probe (the rest of the unit is ok) every year or so.
The trigger for replacement is when it drifts so far that it can't lock on to the corect pH when calibrating.
I've found it to be very reliable and give repeatable results. It is a PCSTestr 35 and has a number of other functions as well.

Yep, sure is.


some require pH 4 solution (the pink/red one) - my work ones actually have to be stored with in pH 4 in the cap.
And soak tehm on a regular basis when not used for a while. Need to check your specific brand.