pH Rises.....Any assistance?

[demariners]

So I went ahead and recalibrated my pH probe. I am going to see how it goes for the next day or 2. Today when I woke up in the morning the pH read 8.28. By the end of the day it read 8.45. I now recalibrated it and going to see what it shows for the day and evening and morning and go from there. I am not sure what else could be raising the pH so quickly.

 

[Randy Holmes-Farley]

FWIW, those last numbers (8.28 to 8.45) are perfect and not unusual for a tank using limewater, IMO.

 

[demariners]

I totally agree but they keep rising. I will take a look today after recalibration. Overnight it did not rise so I think it might have been a calibration issue. I will keep you posted.

 

[Tim Duncan]

I hate to jump in on someone else's thread, but I am having the same issue. My tank is fairly new, about 2 months old, and recently (this week) my PH started constantly rising. When I first got the tank running, my PH was around 8.0-8.2. It's at a point now, that when my lights are on during the day, the PH climbs to 8.6. I am using my Apex probe, which was just calibrated a few weeks ago. I also verified with another test kit, so it isn't the probe calibration. I do 2-part dosing and try to keep my numbers at alk-8, calcium-450, mag-1350. I've had to dose to keep alk and mag up, but calcium has pretty much stayed at 450 without dosing. I am pretty much stumped on what to do. I've tried aeration, but that seems to raise the PH even higher! Please help before things start dying :uhoh2:

 

[Randy Holmes-Farley]

I don't think it likely that with two part and alk at 8 dKH that the pH 8.6 is correct. I'd recalibrate again, maybe even with new buffers. A few weeks is not often enough for calibration when something appears off, and kits are not very useful.

If aeration raised the pH more, then you certainly have measurement error. There is simply no uncertainty about what aeration will do at 8 dKH and pH 8.6.

You are not using new artificial rocks made of cement, are you?

 

[HiggyBrew]

My guess is that your ATO pump flow rate is too high which is causing the kalk slurry at the bottom of the reactor to mix into the saturated water above. This will add too much OH ions to the tank causing a large spike in the tanks pH. You may have better luck using a very low flowrate peristaltic pump. This way the RO/DI input will be very gentle, and will not stir up the slurry. You may also have too much kalk in the reactor for its design. Make sure the kalkwasser is clear and not milky, if it's milky then you are adding concentrated CaOH which is very harsh (caustic). This could cause a runaway pH, drifting upwards. Another possibility would be an extreme evaporation rate, causing large additions of ATO/kalkwasser. I would check that the reactor is working properly first.

 

[joelespinoza]

If you are really having an issue with raising PH and you cant control it even with the correct mag/cal/alk values, and it is not being caused by something removable, like lime filled homemade concrete rocks, then as Randy said greater air exposure is a good way to control the situation without resorting to dosing. The increased exposure of CO2 to the tank water is helpful.

If you are incredibly concerned and are having a long term issue, try something like a larger chamber skimmer or algae scrubber waterfall screen. You dont have to make an actual algae scrubber for this to work (IE it doesnt have to be lit), but hanging waterfall screens are a great way to increase exposure to atmosphere.

 

[joelespinoza]

If you are really having an issue with raising PH and you cant control it even with the correct mag/cal/alk values, and it is not being caused by something removable, like lime filled homemade concrete rocks, then as Randy said greater air exposure is a good way to control the situation without resorting to dosing. The increased exposure of CO2 to the tank water is helpful.

If you are incredibly concerned and are having a long term issue, try something like a larger chamber skimmer or algae scrubber waterfall screen. You dont have to make an actual algae scrubber for this to work (IE it doesnt have to be lit), but hanging waterfall screens are a great way to increase exposure to atmosphere. Here is a couple examples:

http://algaescrubber.net/forums/showthread.php?28-Hundreds-of-Waterfall-Scrubber-Designs