Rain affecting PH

[leon.1980]

Not me.. I have my skimmer line ran outside and it’s a very large skimmer that draws a ton of air and my ph only went up .02 at best… do you have windows or doors open on days it’s not raining and close them for the rain? I can’t see that large of a difference with just a skimmer line outside… the co2 in your home is the only thing that can make that kind of a difference.

And that depends on how much is windows are open and how many people in the house. We are a family of 5 humans and 2 dogs. Our sliding glass door in the upstairs is open a few hours a week. The rest of the time it’s just from people going in or kut or maybe a little airing out of the house.
My ph jumped from 7.8 - 7.9 to 8.0 - 8.15 with just an airline outside. Once I added a co2 scrubber to that line it went as high as 8.6 before I programmed slimy skimmer to shut off at 8.35

 

[SteveMM62Reef]

I pump outside air into my Skimmer, but have noticed higher pH in my Aquarium when we are gone a couple of days. So the house CO2, is still affecting the Aquarium. Your roof, if designed correctly for ventilation, is probably pulling air out of the house, through air leaks in Light Fixtures, and wall electrical boxes. Hotter the roof, the more the air is moving.

 

[Jamie814]

Raindrops strip CO2 from the atmosphere and release it near the ground as the water reevaporates

I've noticed slightly lower pH on rainy or cloudy days as well. I just assumed it was due to less sunlight meaning less photosynthesis in vegetation outside (trees, plants, grass, ect) that consumes the co2 in the atmosphere?
Similar to how the pH drops when lights out in the aquarium due to less photosynthesis.

 

[Court_Appointed_Hypeman]

I've noticed slightly lower pH on rainy or cloudy days as well. I just assumed it was due to less sunlight meaning less photosynthesis in vegetation outside (trees, plants, grass, ect) that consumes the co2 in the atmosphere?
Similar to how the pH drops when lights out in the aquarium due to less photosynthesis.

Certainly could be a contributing factor. Could be measurable, could be negligible, but definitely true.

 

[Randy Holmes-Farley Verified Community Expert]

I think co2 concentration is independant of o2 and both would vary directly with additional moisture

Neither will change with simple humidity changes.

 

[Randy Holmes-Farley Verified Community Expert]

The only ways that I think rainy days can impact pH are:

1. Changes in evaporation based on ATO dosing of alk additives.

2. Reduced light from cloudiness resulting in less photosynthesis.

3. Reduced air exchange with outside air for any of several reasons related to wind or temperature differences or window and door opening/closing.

4. Improved scrubber performance at higher pH.

5. People inside more.

 

[shwareefer]

It might have more to do with additional mousture

I think you nailed it.