PH keeps dropping

[tcoyle]

I know that PH is something to monitor but not stress over. But over the past month or so I am seeing my PH trend down. I am using Kalk in my ATO, have had the windows open for days at a time and still the PH is trending down. It use to be from 8.1-8.3, now I am trending more like 7.9 - 8.1. I don't understand what is going on.

Alk is stable around 8. Anytime we have to close the house up and run the AC, it drops to 7.9 or a bit lower at night and never gets back up above 8.15. I am at a loss as to what might be going on so any help would be great. I just calibrated my PH probe a few weeks ago and its a Lab Grade BRS probe that is only a year old, monitored via my Apex. I have an old probe (stored in a PH solution) that I might try to see what any difference might be, but not sure how reliable it will be with out calibrating that one as well.

 

[jsker]

Check you test kit, I was having the same issue and purchase a new kit and no more issues with testing

 

[tcoyle]

not using a test kit, just the apex PH probe.

 

[Randy Holmes-Farley Verified Community Expert]

The accumulation of CO2 in your home air seems to be the explanation.

I discuss it here:

http://www.reefedition.com/ph-and-the-reef-aquarium/

 

[tcoyle]

I have read that many times, and what confuses me as I am running Kalk in my ATO and what use to be a more stable 8.1-8.3 is now much lower. Opening up the house windows for days does not seem to increase the level like it use to. I would agree that it seems to be a CO2 issue, I just can't figure out how to solve it or if I have some sort of issue with my apex.

 

[Randy Holmes-Farley Verified Community Expert]

I have read that many times, and what confuses me as I am running Kalk in my ATO and what use to be a more stable 8.1-8.3 is now much lower. Opening up the house windows for days does not seem to increase the level like it use to. I would agree that it seems to be a CO2 issue, I just can't figure out how to solve it or if I have some sort of issue with my apex.

If you've done the simple things, I wouldn't worry about it at that pH level, but as a tank matures, there are often more organisms in it, and more organisms can mean a lower pH at night due to release of CO2.

 

[Cory]

According to this website the ph in the ocean is now 8.1

"Today, it is around 8.1, a drop of 0.1 pH units, representing a 25-percent increase in acidity over the past two centuries. The oceans currently absorb about a third of human-created CO2 emissions, roughly 22 million tons a day"

So i wouldnt worry about it.

 

[tcoyle]

So global warming has hit my reef tank in the past month? ha.. At its lowest point so far today it has dropped to 7.8. With the API test kit I bought yesterday it appears to me that the probe is off. When I tested this morning with the lights off it tested (api) around 8.1, but probe was at 7.95. Just ordered another set of test solution to calibrate the probe. Im wondering if my probe is damaged.

The probe itself seems to measure changes much more wildly then before. For instance, when my ATO kicks on it jumps from say 8.0 to 8.5 and then after a few minutes settles back to 8.04 reading. It use to not show the dramatic change that I see now. It would jump from 8.0 to 8.2 and then settle quickly back to 8.04, which is about what I would expect from my 1 tablespoon of Kalk/gallon of rodi water in my ATO.

 

[Cory]

Yes the probe seems bad. Yeah id say our maximum ph when equilibriated with air should be 8.1, not 8.2 anymore.

 

[beaslbob]

try macro and other algae to consume the co2 during the day. Betcha pH will rise above the 8.1 then. LOL

my .02

 

[tcoyle]

try macro and other algae to consume the co2 during the day. Betcha pH will rise above the 8.1 then. LOL

my .02

Yeah I have Chateo in my sump already. I have been trying to keep my fuge light on 24hours a day for the past few days to see if that helped. I think it might be doing the reverse of what I want.

 

[beaslbob]

Good.

then you need more chaeto.

Or possibly the tank just need more time to mature. Sometimes it is best to do nothing.

BTW I "worry" about the just before lights off pH values. The overnight drop is more a function of alk which you seem to have ok. But the just before lights off pH value is an indication of how completely the algae is removing the co2. The idea is the tank becomes a net producer of oxygen and consumer of co2 each 24 hour period.


my .02

 

[tcoyle]

thanks for the input… Right before lights out it drops from like 8.1 to 8.05… Tank has been up for almost 2 years so maturity should not be an issue. I was just concerned that maybe there was something else going on as this is a relative sudden change. Tank still looks good however.

 

[Randy Holmes-Farley Verified Community Expert]

Aside from dosing, aeration, and photosynthesis/respiration, there is not much else that impacts pH.

 

[omykiss001]

didn't see it mentions so forgive if already covered, but when did you calibrate the probe last? Mine when new did drift that way, but stabilized after a couple of months. Calibrate your pH probe and see if there is any change in the reading.

 

[tcoyle]

Aside from dosing, aeration, and photosynthesis/respiration, there is not much else that impacts pH.

Well except for a bad probe…. Inserted my old probe and it read exactly 8.1 same as the API test kit. The BRS probe was reading 7.8 and was getting more wide in the swing. I reached out to BRS and they are sending me a new one as it was still under warranty! Got to love that company!

I am glad I am learning if things don't seem to be aligning to the science or just don't seem right, not to act on it and verify things first. Thanks for all the help and suggestions guys.

 

[tcoyle]

didn't see it mentions so forgive if already covered, but when did you calibrate the probe last? Mine when new did drift that way, but stabilized after a couple of months. Calibrate your pH probe and see if there is any change in the reading.

Yeah I had calibrated it twice and was getting worse. The wild swings from 7.8 - 8.2 had me questioning if I had a problem with my probe. I have never seen a swing that wide before. Even before or after calibrating the probe.