Relationship between O2, CO2, and PH

[jason2459]

Is it normal for there to be a discrepancy in pH between sump water and display tank water? I would think that with a turnover rate of maybe 10x per hour, the water exchange would be happening faster than any differential gas exchange.

Yes, my basement sump and display pH are always different. My sump is directly under my tank now and just an extra 4 feet lower then a sump normally would be under the tank. I've ran my return up to 1400gph and sump would still run higher.

Its been like this through many different probes, calibrations, and even controllers.

I contribute it to the fact that's where my skimmer is aerating the water. And where my limewater is dosed. So will have the strongest effect of both.

 

[Cas8100]

Jason,

It looks like your difference is about 0.1, which makes sense. The other guy was talking about a 0.7 difference. That seems more significant to me.

 

[jason2459]

Jason,

It looks like your difference is about 0.1, which makes sense. The other guy was talking about a 0.7 difference. That seems more significant to me.

I would be surprised if it's accurate.

I would get some Borax and test
http://web.archive.org/web/20010211...twork.com/fish2/aqfm/2000/feb/bio/default.asp


Edit: you also only asked if it was normal for them to be different. Not in any specific way or by any certain amount.

 

[Reefable]

Hi Guys
I know what you guys mean and i am in the same boat but the fact that everything seems healthy and normal in my display is a proof that Ph isnt that low in there as my Apex probe is showing. To test the accuracy of the PH probe i dipped it in the Kalkwasser solution and it showed 11.8 in the same boiler room. The difference between my display and sump is approximately 40'ft of piping. The difference between the two readings for sure raise lots of questions considering the rate at which the water is being circulated (Reeflow barracuda pump). I am going to test the Display water again today with some lab grade test strips (I work in a college so i can get the high end strips) and see what it shows.

Jason thanks for the link i will look into Borax too...Ultimately if everything looks ok than i will leave it at that..Will post the updates later tonite when i retest the Ph of my display...lol my sump Ph shows 7.37 right now :headwally:

 

[bertoni]

Is it normal for there to be a discrepancy in pH between sump water and display tank water? I would think that with a turnover rate of maybe 10x per hour, the water exchange would be happening faster than any differential gas exchange.

I wouldn't say that such a difference is common, but it's certainly possible. If the sump is in a room with a lot of carbon dioxide, it might happen, especially with the skimmer attached to the sump. I don't have the equipment to test that guess, though.

 

[Reefable]

Ok I spoke to my lab technician and he loaned me a portable Ph meter from Henna. I will check it out tonite. He mentioned something interesting which I would like to share and MIGHT BE A CONTRIBUTING FACTOR of low Ph in the sump. He mentioned there is a relationship between Temperature and Ph. I know my sump temperature has gone down to 73 from 80 when I moved my sump below as it sits towards an exterior wall. most recently I took off one heater thinking its always hot down there. I also added a fan to circulate some air in there. These r all contributing to lower the temperature imo and might be the real issue. I will still test the display ph tonite with the portable meter and update u. Thanks


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[Reefable]

Ok here is the update. So it is my ph probe giving me wrong results. As you can see from the pics below the big difference in the Ph readings than compared to Apex Probe.

First picture is what Apex shows

Second picture is from portable probe from my Display

Third picture is from my Sump in the basement taken by portable probe

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[bertoni]

I suspect that there's an electrical interference problem, then, if the AquaController calibrated properly. It's possible that the calibration solutions are off, though.

 

[Reefable]

I suspect that there's an electrical interference problem, then, if the AquaController calibrated properly. It's possible that the calibration solutions are off, though.

Hi Bertoni the probe I used is not from the Apex to get a second opinion. I used a different probe from my chemistry lab at work.


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[Reefable]

I retested my ph again now with the portable ph probe from henna and my ph showed rock solid at 8.16 on both display and sump


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[jason2459]

I retested my ph again now with the portable ph probe from henna and my ph showed rock solid at 8.16 on both display and sump


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Very nice. I had high doubts the other reading was accurate. I agree with Bertoni that there's some interference with your other probe and could be something not even close by.

For instance my conductivity probe worked great for years and then I moved my sump location in my basement closer to under the tank but still in the basement. After that move my conductivity readings fluctuated wildly daily and tried calibrating it several times.

Trying to track down the cause I noticed a rhythm and ended up tracing it to when my T5s, used to supplement my LEDs, would turn on. The ballast a good 10 to 12 feet away on another floor was causing enough interference I assume electromagnetic to cause my conductivity to go crazy. Changed ballasts and went away and has worked fine since.

 

[jason2459]

And FWIW my sump is also by my furnace and windows closed pretty much year round. As you saw in my screen shot from this morning my pH drops pretty good.

But my pH difference from DT to Basement sump is around .1 to .2 consistently. Your numbers threw red flags to me.

 

[Reefable]

And FWIW my sump is also by my furnace and windows closed pretty much year round. As you saw in my screen shot from this morning my pH drops pretty good.

But my pH difference from DT to Basement sump is around .1 to .2 consistently. Your numbers threw red flags to me.

Yeah tht was always a question to me too and hence I went and loaned another probe from my lab and bam tracked the issue. How do I know or trace the electrical interference now to my apex probe or shall I get a new probe altogether?


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[jason2459]

Yeah tht was always a question to me too and hence I went and loaned another probe from my lab and bam tracked the issue. How do I know or trace the electrical interference now to my apex probe or shall I get a new probe altogether?


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It would be very hard to say. I was lucky in that what was causing my issue was also connected to my apex and I pulled up graphs comparing on times with when my conductivity probe would go haywire.

Usually conductivity probes are much more sensitive to things like that. It's rare it happens to a pH probe on the Apex. On older controllers it was more common but the Apex uses a Galvanic Isolation but it's not unheard of to have something still interfere with the pH probe.

 

[Reefable]

Ok thanks I will get a new proble just incase


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