Questions about Ph

[Jedi Knghit]

We were away from home for 3 days, upon returning home we found one of three fish dead. I tested the water and everything was normal and about the same in the tank except for Ph. It jumped from the 7.8-7.9 range that the tank normally maintains. I suspect lower CO2 levels in the home, due to a lack of occupants, allowed the tank to exchange CO2 for O2 and raised the Ph. Is that a reasonable explanation?

Would a .3 change in Ph be enough to kill a fish if it were already stressed due to disease?

Thanks.

 

[Larry L]

It jumped from the 7.8-7.9 range that the tank normally maintains. I suspect lower CO2 levels in the home, due to a lack of occupants, allowed the tank to exchange CO2 for O2 and raised the Ph. Is that a reasonable explanation?

Yes, lower CO2 levels would account for the pH increase you saw. It's not that it's exchanging CO2 for O2 (pH has nothing to do with O2 levels), it's just that lower levels of CO2 in the air means lower levels of CO2 dissolved in the water since (if gas exchange is good enough) they will usually reach an equilibrium.

Would a .3 change in Ph be enough to kill a fish if it were already stressed due to disease?

I doubt it, my pH swings almost that much every day just due to normal photosynthesis cycles.

 

[jsker]

Yes, lower CO2 levels would account for the pH increase you saw. It's not that it's exchanging CO2 for O2 (pH has nothing to do with O2 levels), it's just that lower levels of CO2 in the air means lower levels of CO2 dissolved in the water since (if gas exchange is good enough) they will usually reach an equilibrium.



I doubt it, my pH swings almost that much every day just due to normal photosynthesis cycles.

+1

 

[Jedi Knghit]

Thanks Larry. I was thinking along the right lines, just off a bit on the actual science.

 

[Randy Holmes-Farley]

The pH change wasn’t the cause of the fish deaths. A power failure while gone might have been. That’s a common disaster scenario.

 

[Jedi Knghit]

Good suggestion, but I would have been alerted that our smart thermostat lost connectivity to the cloud. None of the digital clocks lost the time either.

I believe I have ick in the tank as the fish that died was scratching occasionally for a few weeks. It wasn't flukes as confirmed by multiple FW dips. I was planning to QT and fallow the DT to eliminate it when we returned, but she didn't make it long enough. . She was a very finicky eater. I suspect she didn't eat well with the automated feeder and succumbed to ick. The two clown fish were not eating well and looked a little lethargic too. Got the QT up to 1.0 copper power and moved them over yesterday. They seem to be looking a little better already and eating more.