High PH - Normal dKH

Elgringodiablo · May 16, 2018

Hi Guys-

I am running a kalk reactor to my 15 gallon frag tank. I set my Apex to not feed the ATO/reactor if the PH exceeded 8.6. Came home the other day to find my return pump almost run dry because my ATO/kalk reactor was off due to the high PH.

Tested my dKH with the Hanna Checker and I'm sitting at a comfortable 8.6.

I've added a airstone to the return chamber to see if I can lower my PH that way. It's currently sitting at 8.77, I just recalibrated it with new packets of 7.00 & 10.00 milwaukee solution.

Corals look fine, airstone doesn't seem to be doing anything to my PH, just microbubbling my frag tank. I will try calibrating again in a few to see if it's just not reading correctly. Otherwise I am at a bit of a loss. Maybe add vinegar to my kalk reactor??

I wouldn't normally chase PH, but north of 8.6 seems bad.

Elgringodiablo · May 16, 2018

Recalibrated my PH probe again. No changes...
Added about 10ml of white vinegar to my frag tank and got the PH down to 8.62, still a little high, but not quite as nuts as it was. I also added about 15ml of vinegar to my 1.5L Avast Kalk Stirrer.

Not really freaking out, but it seems counter-intuitive that I should set a PH triggered off switch at a level I am way over and to have such high PH without abnormally high dKH. Can high PH actually wipe my livestock, or is the real concern a big Alkalinity spike?

Randy Holmes-Farley · May 16, 2018

I expect it is inaccurate, even with new calibration. Try measuring the pH in a cup of water away from the tank. Simple aeration will readily lower the pH if it really was that high.

Elgringodiablo · May 16, 2018

Retested the same frag tank water and the same probe in a cup away from the tank. Still showing 8.65 PH. Also tested a cup of new RODI water, which came in at 9.06 PH. Think it's the probe or my water? If the PH stays high like this, I will retest my dKH in a couple hours and make sure it's still around the same 8.6 range.

Randy Holmes-Farley · May 16, 2018

Elgringodiablo said:
Retested the same frag tank water and the same probe in a cup away from the tank. Still showing 8.65 PH. Also tested a cup of new RODI water, which came in at 9.06 PH. Think it's the probe or my water? If the PH stays high like this, I will retest my dKH in a couple hours and make sure it's still around the same 8.6 range.

RO/DI can read very high (mine did) and is unreliable.

Try the aeration test, except in reverse where it will drop if accurate:

pH And The Reef Aquarium
http://www.reefedition.com/ph-and-the-reef-aquarium/

The Aeration Test

Some of the possible causes of low pH listed above require an effort to diagnose. Problems 3 and 4 are quite common, and here is a way to distinguish them. Remove a cup of tank water and measure its pH. Then aerate it for an hour with an airstone using outside air. Its pH should rise if it is unusually low for the measured alkalinity (Figure 2). Then repeat the same experiment on a new cup of water using inside air. If its pH also rises, then the aquarium’s pH will rise simply with more aeration because it is only the aquarium that contains excess carbon dioxide. If the pH does not rise in the cup (or rises very little) when aerating with indoor air, then that air likely contains excess CO2, and more aeration with that same air will not solve the low pH problem (although aeration with fresher air should). Be careful implementing this test if the outside aeration test results in a large temperature change (more than 5°C or 10°F), because such changes alone impact pH measurements.

Elgringodiablo · May 16, 2018

Randy Holmes-Farley said:
RO/DI can read very high (mine did) and is unreliable.

Try the aeration test, except in reverse where it will drop if accurate:

pH And The Reef Aquarium
http://www.reefedition.com/ph-and-the-reef-aquarium/

The Aeration Test

Some of the possible causes of low pH listed above require an effort to diagnose. Problems 3 and 4 are quite common, and here is a way to distinguish them. Remove a cup of tank water and measure its pH. Then aerate it for an hour with an airstone using outside air. Its pH should rise if it is unusually low for the measured alkalinity (Figure 2). Then repeat the same experiment on a new cup of water using inside air. If its pH also rises, then the aquarium’s pH will rise simply with more aeration because it is only the aquarium that contains excess carbon dioxide. If the pH does not rise in the cup (or rises very little) when aerating with indoor air, then that air likely contains excess CO2, and more aeration with that same air will not solve the low pH problem (although aeration with fresher air should). Be careful implementing this test if the outside aeration test results in a large temperature change (more than 5°C or 10°F), because such changes alone impact pH measurements.

So basically run an airstone in a cup of the tank water for an hour and see if the PH drops down to a normal rate?

Randy Holmes-Farley · May 17, 2018

Elgringodiablo said:
So basically run an airstone in a cup of the tank water for an hour and see if the PH drops down to a normal rate?

Yes. Inside air is fine.

Elgringodiablo · May 18, 2018

Did the aeration test on a 100ml cup of tank water. Got the PH in the cup back down to 8.25 after aerating for an hour.

Meanwhile the tank PH is 8.7 and the dKH has gone up from 8.6 to 9.1.

Based on those results am I looking at a Kalkwasser overdose? Thinking I should take the reactor offline and do a water change.

Randy Holmes-Farley · May 18, 2018

You are looking at a need to aerate more. Water changes are not good ways to deal the CO2 equilibration issues. If you cannot aerate more, you might switch to a lower pH additive that doesn’t drive CO2 consumption.