Hi PH problems

[glenvdm]

I have a 30G biocube thats been up and running for a year and a half now, i have a neptune AC3 connected to it monitoring the temp and PH, however my PH fluctuates wildly, during the day it gets as high as 9.5 and in the evening it gets to 8.0. what could cause the huge deviations in the ph? i understand that ph does lower at night, but never thought that it would ever get as high as 9.5? i have calibrated the probe many times, so i know the probe is reading actual ph.

[joemelo]

If you head over to the reef chemistry thread, randy has some blogs posted. or even post this on that thread and I'm sure he will respond.

[glenvdm]

Thanks joemelo, had a read there and was very helpful!!

[disc1]

I have a 30G biocube thats been up and running for a year and a half now, i have a neptune AC3 connected to it monitoring the temp and PH, however my PH fluctuates wildly, during the day it gets as high as 9.5 and in the evening it gets to 8.0. what could cause the huge deviations in the ph? i understand that ph does lower at night, but never thought that it would ever get as high as 9.5? i have calibrated the probe many times, so i know the probe is reading actual ph.

Your pH probe is wrong. I promise your tank water isn't going to pH 9.5 or there would be a snowstorm of massive proportions.

There could be electrical interference, a bad probe, or a probe that needs to be calibrated.

[IslandCrow]

Are you dosing anything? If not, I'm with disc1. It seems extremely unlikely your PH could be getting that high if you're not adding something very alkaline to your water. When was the last time you calibrated your probe? Also, low batteries can cause measurement errors.

[Chris27]

Take out some tank water, put it in a cup, and use your pH meter to measure the water away from the tank....likely it will be around 8.2 if the meter is calibrated properly with a proper power source.

[Randy Holmes-Farley]

I agree. This is clearly testing error.

[glenvdm]

thanks guys, i used another ph meter i had in a cupboard and yip my probe has seen better days, the tank measures 9.05 on the AC3 but measured 8.19 on the other PH meter, guess i need a christmas present now!!

[Randy Holmes-Farley]

Good to hear.

In general, no reef tank will have unacceptably high pH in the absence of dosing high pH additives. And if the pH is getting high, more aeration will bring it down.

This has more:
High pH: Causes and Cures
http://reefkeeping.com/issues/2005-03/rhf/index.htm