pH measurement issues

dedvalson · Post by **dedvalson** » Thu Nov 03, 2011 6:41 am

Hi,

I have been running my Reef Angel system a little over a month now.

Twice I have had a strange thing happen and I am looking for some ideas as to what might be going on.

Last night at about 10:30 PM, the pH as shown by the RA suddenly went from 8.1 or so (where it normally runs) to 8.5. Over the next 3 hours or so the measured pH swung wildly from 7.9 to 8.5 then suddenly settled back down at about 7.9.

This is the second time this has happened, it happend once about 4 nights ago also. That time the measured pH went as high as 9.5.

After the first incident I cleaned and recalibrated the pH probe. During the first incident I also measured my pH using my Hannah pH meter and it read normal (about 8.05) even while the RA was reading over 9.

It is odd because it seems to happen very suddenly, behave very wildly, and then go back to totally normal behavior.

Last night when it happened no one was even in the room with the tank when all of this happened, so I don't think that it could have been due to some sort of human interference.

I would invite any suggestions about how I might troubleshoot what is going on here.

Don

wolfador · Post by **wolfador** » Thu Nov 03, 2011 6:44 am

which version of the library are you running? There was a bug at one point with the pH averaging that caused that issue on mine.

dedvalson · Post by **dedvalson** » Thu Nov 03, 2011 7:12 am

Hi,

I am running dev libraries 0.8.5.19

Thanks,

Don

rimai · Post by **rimai** » Thu Nov 03, 2011 8:14 am

If you have stray voltage in the tank, even if it is undetectable, it could cause that, especially if you have the USB-TTL cable connected to a computer, where ground loop is created.
I have a tank at the office that my skimmer would do that.
I since replaced the skimmer and never had the problem again.

dedvalson · Post by **dedvalson** » Thu Nov 03, 2011 10:57 am

The USB-TTL cable is not connected to a computer, the Wireless adapter is connected to that port.

There is nothing in the tank that turns on or off during those hours.

I guess I will have to watch to see if something somewhere else in the house comes on when this happens.

Don

dedvalson · Post by **dedvalson** » Thu Nov 10, 2011 2:09 pm

I think I may have found a fix for this.

The probe was sitting with the tip touching the bottom of my sump. I relocated it an inch or so off of the bottom of the sump and it has been solid since.

Don't know if that makes sense or not but it seems to have fixed it.

Don

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