View Full Version : Do the temp and PH probes have to be replaced regularly to prevent a tank crash?
Allentown
02/22/2015, 04:59 PM
Same as title.
My heaters of course have internal thermostats so hopefully a bad temp probe wouldn't cause melt down but i do base my kalk in the ATO ratio on the ph probe.
Question: Do the probes start reading wrong before they go bad (and if so, at what time interval) or do they just stop working.
If it is the former i need to know because im currently building a fund for back up gear (back up main pump, back up skimmer, back up wave makers etc.).
kurt_n
02/22/2015, 09:41 PM
Been running the Apex for 4-1/2 years and am still on the same temp probe. No issues with it. With that said though, I do have a spare in the closet!
As far as pH probe, I've found it varies on the manufacturer. When they start to go bad, you'll find that they don't hold their calibration for very long and will quickly drift. I've had some that only stay good for a year, others can go for a couple years. If I was using a pH probe to actually control anything, I'd probably replace it yearly, just to be safe.
Jyetman
02/23/2015, 02:54 PM
How far is considered drifting are we talking large swings?
Allentown
02/27/2015, 08:28 PM
How often do you calibrate?
kurt_n
02/27/2015, 10:29 PM
...When they start to go bad, you'll find that they don't hold their calibration for very long and will quickly drift. I've had some that only stay good for a year, others can go for a couple years...
Y'know... this isn't the first time I've written something in a post and then within days had whatever I've written about act up on me! Grrrrrr....
I just had my 2-1/2 year old pH probe go bad on me. This one went dead a little different than other ones. I've been noticing my pH slowly creeping up this winter - which is unusual. Most folks' pH will drift down during the winter because their house is buttoned up tight and the CO2 levels rise.
Regardless... my pH was reaching unusually high levels (for me) at the end of the day - around 8.30. So the other day I recalibrated. It held calibration just fine (it read the 7 and 10 solutions perfectly after calibration, which you should always go back and double-check), but then slowly started going up even higher. End of day found me at 8.40.
Next day... same thing - by 6pm or so, I was already at 8.4 and it never went any higher. I *knew* my pH wasn't that high, so I ordered a new probe and cursed this thread. :)
New probe installed tonight, calibrated, and thing are back to normal. Lights just turned off and I'm at 8.19... about where I'd expect to be.
Soooo... moral of the story is that what I said before about them not holding calibration when they're dead isn't really 100% accurate. That's the way they've failed on me before, but this time it appeared to hold calibration just fine. It was just drifted high, really quick. So I guess I'd say if your pH probe isn't making sense, and it's older than 12-18 months old, consider replacing it.
[Edit: FYI... 2.5 years is really good life for a pH probe, from what I've heard. It was a Pinpoint, if anyone's interested.]
kurt_n
02/27/2015, 10:33 PM
How often do you calibrate?
I don't control anything based on pH - except for turning off my alk dosing if it gets too high. So I only calibrate every 3-4 months or so, or if things don't seem right.
If I was controlling something critical with pH, say a Ca reactor, then I'd probably calibrate monthly.
Meitzler
03/22/2015, 06:27 PM
I have been going over 4 years with my apex. The temperature sensors are reliable. Ph probes are a problem. Some last from a few months to a few years. I agree with an earlier post that you will see drifting reading, that get progressively worse in many cases. I use two pH probes in the sale tank and when they vary by more than.7, I do a recalibration and cleaning. I do use it to control my max pH when dosing Kalk. I check both probes in the control.
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