Why is my pH doing this??

[ShanePike]

OK. Brand new Milwaukee pH probe calibrated with brand new Hanna 7.01 and 10.01 calibration fluids. pH started at 8.78 at 3:27 ET when I first calibrated and has climbed to 8.93 an hour later. Alk is still at 7.

Why would my pH be so high?? There is nothing photosynthesizing in this tank except a light dusting of what looks like diatoms in the darkest corners and normal film algae that develops like usual on the glass (and presumably other surfaces).

 

[Garf]

OK. Brand new Milwaukee pH probe calibrated with brand new Hanna 7.01 and 10.01 calibration fluids. pH started at 8.78 at 3:27 ET when I first calibrated and has climbed to 8.93 an hour later. Alk is still at 7.

Why would my pH be so high?? There is nothing photosynthesizing in this tank except a light dusting of what looks like diatoms in the darkest corners and normal film algae that develops like usual on the glass (and presumably other surfaces).

Did you add aeration / circulation? Does the cable to the pH probe cross any other power cables?

 

[Randy Holmes-Farley]

Seawater at that alk won’t have a pH that high after any reasonable aeration. If aerated seawater does have pH that high, it is test error for alk or pH.

 

[ShanePike]

Did you add aeration / circulation? Does the cable to the pH probe cross any other power cables?

Seawater at that alk won’t have a pH that high after any reasonable aeration. If aerated seawater does have pH that high, it is test error for alk or pH.

Thank you for the responses on this! I've lost count of how many tanks I've set up, and this one should have been the easiest of them all. Instead, I'm stuck dealing with a problem that baffles me. I still can't put zoas in this tank without them closing up, and stomatellas still begin to die within minutes. Meanwhile, the new fish in this tank still seems to be doing fine 10 days after the problem began, and the amphipod and mini nassarius populations seem to be completely unaffected. I'm completely stumped.

It does appear that the pH issue is a measurement problem, though. I took a small container of water to my other tank and put its pH probe in it. That probe quickly returned a reading of 8.38 — still higher than I think it ought to be, but far below the 8.99 that the other probe was reading.

The tank has heavy surface aeration plus aeration as the water falls through the weir. I had moved the pH probe to try to eliminate any interference, but I just moved it completely so that the wire doesn't cross anything. The pH reading didn't change. I'm also confident in my Alk measurement, because I've been testing Alk for a long time and this Alk test also shows results on my other tanks that I would expect.

I determined earlier today that this Apex isn't reading temperature correctly either. I thought that was just a calibration issue, but now it seems like the Apex is the problem.

But still no answer on what's actually wrong with the tank :/

 

[Garf]

Thank you for the responses on this! I've lost count of how many tanks I've set up, and this one should have been the easiest of them all. Instead, I'm stuck dealing with a problem that baffles me. I still can't put zoas in this tank without them closing up, and stomatellas still begin to die within minutes. Meanwhile, the new fish in this tank still seems to be doing fine 10 days after the problem began, and the amphipod and mini nassarius populations seem to be completely unaffected. I'm completely stumped.

It does appear that the pH issue is a measurement problem, though. I took a small container of water to my other tank and put its pH probe in it. That probe quickly returned a reading of 8.38 — still higher than I think it ought to be, but far below the 8.99 that the other probe was reading.

The tank has heavy surface aeration plus aeration as the water falls through the weir. I had moved the pH probe to try to eliminate any interference, but I just moved it completely so that the wire doesn't cross anything. The pH reading didn't change. I'm also confident in my Alk measurement, because I've been testing Alk for a long time and this Alk test also shows results on my other tanks that I would expect.

I determined earlier today that this Apex isn't reading temperature correctly either. I thought that was just a calibration issue, but now it seems like the Apex is the problem.

But still no answer on what's actually wrong with the tank :/

What's wrong with the temperature then? Are you relying on a salinity probe on this Apex?

 

[ShanePike]

What's wrong with the temperature then? Are you relying on a salinity probe on this Apex?

Since I hooked it up on Jul 31, I have always suspected that the temperature was reporting incorrectly. So I bought a brand new probe and an NIST thermometer and calibrated it today. The probe was reading 79.3, but the thermometer was reading 77.9. And when I calibrated it, nothing happened. The Apex still reported the temp as 79.3.

I posted on the Neptune support forum this morning, but haven't gotten an answer yet:

Temp Probe not Calibrating

I bought a new temp probe. It seemed to be reading high, so I bought an NIST thermometer to calibrate it. The temp probe is currently reading 79.3. The thermometer is reading 77.9. So I went through the calibration process: 17151 17152

forum.neptunesystems.com

And nice catch on the salinity probe! Thankfully, no. I'm using a Tropic Marin hydrometer to measure salinity.

 

[ShanePike]

OK, I have another clue.

This morning:
7 AM - Lights came on.
9 AM - I wanted to see if pH would keep climbing even if the lights were off, so I turned them off completely.
11:30 AM - I noticed that the water looked much cloudier, so I turned on the lights again. Sure enough, the water had gotten very cloudy.

I don't think it's quite as cloudy as it was on July 28 when I had the tank covered and lights off for a couple hours, but it's definitely way cloudier than when I turned off the lights at 9 AM and way cloudier than it has been since July 28.

This is the second time now that I have turned off the lights completely after having them on for a while, and both times the water got really cloudy. The first time was on July 28 when this problem began. That doesn't seem like a coincidence to me.

Can you think of anything that would make the water cloud up when the lights were suddenly shut off?

 

[Randy Holmes-Farley]

Dinos are known to enter the water column when lights are off.