PH calibration sudden shift, broken?

zsxking · Post by **zsxking** » Sun Mar 16, 2014 11:50 pm

I have been running reef angel for couple months, and having a kind of stable PH, 8.3 before light off and 8.0 before light on.

But this morning the ph reads 8.5, unusually high. My first suspect is the sensor error. So I tested the 7.0 calibration solution, read 7.8. Then I recalibrated it and it reads 8.1, kind of normal.

But then tonight, the reading jumps up to 10.0! 7.0 calibration solution read 8.5. I can surely calibrate it again, but is that normal that this happen?

I have another ph sensor, tried it without calibrate again, reading is similar (+0.5). That is the same difference when using the same calibration numbers. So the sensor should not be the cause of this big change.

Tried to unplugged everything else, not helping. Measure the voltage of tank water, get only 2v, not too big a deal.

Is it normal that the calibration values changed so much in half a day? Or doea this mean something is wrong? If yes, what went wrong? Then main unit?

rimai · Post by **rimai** » Mon Mar 17, 2014 9:10 am

Can you place the probe into a cup with tank water and see what happens?

KRavEN · Post by **KRavEN** » Mon Mar 17, 2014 8:31 pm

Strange coincidence maybe but my pH was reading normal last night and yesterday. Today it's reading 1.0. I tried rebooting/power cycling the RA and rinsing the probe in RO water. No change. Next I'm going to hook the probe to a pinpoint monitor and calibrate with that to make sure the probe is good. It's a pinpoint probe.

RootsRockReefer · Post by **RootsRockReefer** » Wed Mar 26, 2014 7:40 pm

Kraven,
Your experience seems to be identical to mine. Any change in your results.

Robert1969 · Post by **Robert1969** » Wed Apr 02, 2014 6:55 am

Things that have given me false PH levels in the past:
1. It was out of the water
2. Bad ATO float
3. Bad temp probe
4. Or sometimes the probe falls out of calibration or it just fails and I need to buy a new one.

Today I am getting alerts my PH is 7.5. Time to start looking to see what's wrong in my tank now.
I kind of think of my PH probe as an alert system, and when it starts acting funny it's time it investigate.

heatdissipation · Post by **heatdissipation** » Wed Apr 02, 2014 7:06 pm

Mine is reading the exact same thing. 1.0. I tried calibrating it in 7, and 10 solution, but still reads 1.0. My whole setup is a little over a month old, so I don't think the probe age is a problem. I tried setting it in an isolated cup of tank water, I unplugged everything off my controller and calibrated it, I left everything plugged in and calibrated it. I don't have my USB-Ttl cable plugged in when I am calibrating it, I have tried everything that I could find on here but I still get 1.0.

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