Low pH of 7.8, despite perfect alkalinity and surrounding oxygen. Help!

[Herides]

Hey guys,

According to my Seneye Reef, my pH is at 7.8 and has been dropping for a while until now, not dramatically but over a long period of time and seems to be settling at 7.8. I've been testing my alkalinity during this process and my alkalinity comes out at more often around 3 Meq/L, after looking up advice and seeing a BRS video for increasing pH, one thing they recommended opening a window for a few hours to let fresh oxygen in (as the tank is in my room and I am also always in my room so maybe i breath too much CO2), even after letting the window open without me in it for a few hours, still no hint of pH getting better. The tank is a 40g breeder and the only things in it at the moment are 2 clowns if that helps, and I don't have a sump and am unable to add one.

 

[Randy Holmes-Farley]

Sounds like a Seneye problem, not an aquarium problem, based on the statement " has been dropping for a while until now, not dramatically but over a long period of time ".

FWIW, oxygen has nothing to do with pH. it is accumulated indoor CO2 that is important.

You can try this aeration test:

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.

 

[Herides]

Sounds like a Seneye problem, not an aquarium problem, based on the statement " has been dropping for a while until now, not dramatically but over a long period of time ".

FWIW, oxygen has nothing to do with pH. it is accumulated indoor CO2 that is important.

You can try this aeration test:

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.

I went to my lfs right after work and got an independent pH test kit. Turns out the seneye is lying to me (or at least the slide is for this month) so I've adjusted the trim and now I think everything is OK. I had previously thought about if the seneye was wrong but thank you for confirming those thoughts for me!!

How did you think the seneye was wrong, is it the case where like, the pH value if it was an actual change would happen within the span of a day as opposed to several days?

 

[taricha]

How did you think the seneye was wrong, is it the case where like, the pH value if it was an actual change would happen within the span of a day as opposed to several days?

pH moves in a daily cycle of up and down due to photosynthesis etc. not a long slow multi-day drop. That's what made the pH data sound sketchy.