Rain affecting PH

[Gill the 3rd]

This is more of a curiosity question and to see if other people have experience this. The PH in my tank used to run 7.8-8.0 until I ran my skimmer intake to the outside. My tank now typically runs between 8.1-8.3. I have noticed that when we have rain over a couple of days, my PH drops to 8.0. When the rain stops, my PH climbs again to 8.3 the next day. Just curious if this happens to anyone else and why it happens?

 

[Troylee]

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.

 

[Gill the 3rd]

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.

My sump is in my basement so no open windows or doors. We typically keep our windows closed regardless of weather and I have 2 kids and 2 dogs, so I'm sure we have a good build up of CO2 in our home. Running the skimmer intake outside had a noticeable difference on my PH.

I don't really care that it drops to 8.0, I'm more curious as to why. Like you said, I would think it wouldn't make a difference.

 

[taricha]

I wonder if water gets on/in the airline outside and slows the flow of outside air being pulled into the skimmer.

 

[Gill the 3rd]

I wonder if water gets on/in the airline outside and slows the flow of outside air being pulled into the skimmer.

I thought that as well, but its under a deck and stays dry

 

[taricha]

Rainy days also have lower pressure, so I wonder if the house is well sealed enough that on rainy low pressure days the skimmer suction is too weak to pull in air as quickly as it would on a higher pressure good weather day.

(It's a stretch, lol. Random fluctuations in your pH measure that happened to coincide with a couple of rainy days seems at least as likely.)

 

[Gill the 3rd]

Yea I'm leaning towards it being a coincidence. I will continue to pay attention to it.

 

[Garf]

Yea I'm leaning towards it being a coincidence. I will continue to pay attention to it.

Don’t supposed you have Kalkwasser in your top off water?

 

[Gill the 3rd]

Don’t supposed you have Kalkwasser in your top off water?

I dose Kalk via a doser, not in my ATO. I dose continuously over 24 hours. My PH during lights out is 8.1 and is 8.3 when lights are on. When we have rain for an extended period of time is when I noticed it dropped to 7.9 to 8.0.

 

[Court_Appointed_Hypeman]

Rain does cause a drop in PH, I'm not 100% sure of the mechanism, but it must have to do with a change in local atmosphere composition. I notice high humidity has the same affect, just to a lesser extent. I think it increases the local concentration of CO2, either by causing stuff to gas off from the ground, or pulls co2 from the upper atmosphere down by disolving into the water as it falls and then gasses off.

I notice the affect whether our house is open or not, but the affect appears to be far greater at face value with the house open given it can be up to 1.5 lower during rain, but my PH is higher with windows open so the 8.25 I sit at with windows open on a rainy day looks wat better than the same drop with windows shut to 8.05 down from 8.4 and 8.2 respectively.

 

[Troylee]

I dose Kalk via a doser, not in my ATO. I dose continuously over 24 hours. My PH during lights out is 8.1 and is 8.3 when lights are on. When we have rain for an extended period of time is when I noticed it dropped to 7.9 to 8.0.

That makes more sense than a top off.. with higher humidity we have less evap obviously so a kalk top off wouldn’t help much.. I know I’m playing that game currently lol

 

[Garf]

I dose Kalk via a doser, not in my ATO. I dose continuously over 24 hours. My PH during lights out is 8.1 and is 8.3 when lights are on. When we have rain for an extended period of time is when I noticed it dropped to 7.9 to 8.0.

I expect you don’t like the rain and stare into your tank all day, breathing on it

 

[taricha]

Rain does cause a drop in PH, I'm not 100% sure of the mechanism, but it must have to do with a change in local atmosphere composition. I notice high humidity has the same affect, just to a lesser extent.

Now I want to take a CO2 monitor and go measure the wooded area behind my house when it's dry, versus after a rain. Makes me wonder if the moisture from the rain kickstarts decomposition processes that would increase CO2 in the outside air near the ground.

 

[rhitee93]

It might simply be that on rainy days the gas you pull in through the tube has a higher concentration of water vapor in it therefore less oxygen to dilute the CO2 in your system.

 

[Court_Appointed_Hypeman]

It might simply be that on rainy days the gas you pull in through the tube has a higher concentration of water vapor in it therefore less oxygen to dilute the CO2 in your system.

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

 

[Court_Appointed_Hypeman]

Now I want to take a CO2 monitor and go measure the wooded area behind my house when it's dry, versus after a rain. Makes me wonder if the moisture from the rain kickstarts decomposition processes that would increase CO2 in the outside air near the ground.

I'd be very curious as to what the results are.

Because I think the difference between 8.4 and 8.25 is pretty absurd if you think about it, that outdoor CO2 ppm would shift that dramatically, but who knows.

It might have more to do with additional mousture reducing the exchange of air from within the home to the outside, but we have a whole house fan we use pretty frequently, so I would assume our CO2 concentration would vary directly with outside air and only be a little elevated in conparison.

If you do this, tag me

 

[jda]

If you let me know the before and after co2 readings, I can run it through the Co2Sys model and see what it anticipates for a difference. My guess is not that much... in my house, my tank pH barely moves from 420ish ppm of co2 all the way up to 700ppm.

According to the model a change from 8.4 to 8.25 is like 450 vs like 850 ppm of co2 which is not likely outside... especially the 850ppm.

My guess is that the rain affects the fresh air down the pipe to the skimmer and what you are seeing is the difference between good gas exchange with low-co2 air vs the higher co2 air that is in the home all of the time. Another guess is that if the home was at outdoor-level co2 then this would not be a thing at all.

dKH: 9.0 , Alk: 3240.0
co2: 500
pH NBS: 8.226
tank pH Est: 8.446

dKH: 9.0 , Alk: 3240.0
co2: 850
pH NBS: 8.033
tank pH Est: 8.253

 

[Court_Appointed_Hypeman]

If you let me know the before and after co2 readings, I can run it through the Co2Sys model and see what it anticipates for a difference. My guess is not that much... in my house, my tank pH barely moves from 420ish ppm of co2 all the way up to 700ppm.

According to the model a change from 8.4 to 8.25 is like 450 vs like 850 ppm of co2 which is not likely outside... especially the 850ppm.

My guess is that the rain affects the fresh air down the pipe to the skimmer and what you are seeing is the difference between good gas exchange with low-co2 air vs the higher co2 air that is in the home all of the time. Another guess is that if the home was at outdoor-level co2 then this would not be a thing at all.

dKH: 9.0 , Alk: 3240.0
co2: 500
pH NBS: 8.226
tank pH Est: 8.446

dKH: 9.0 , Alk: 3240.0
co2: 850
pH NBS: 8.033
tank pH Est: 8.253

My PH varies quickly with each extra person in the house or once closed up. I can tell from work when someone gets home down to the 10 minutes. Might be a gas exchange factor, I have quite a lot that happens independently of my skimmer.

 

[vetteguy53081]

This is more of a curiosity question and to see if other people have experience this. The PH in my tank used to run 7.8-8.0 until I ran my skimmer intake to the outside. My tank now typically runs between 8.1-8.3. I have noticed that when we have rain over a couple of days, my PH drops to 8.0. When the rain stops, my PH climbs again to 8.3 the next day. Just curious if this happens to anyone else and why it happens?

I have not seen this but air I believe is more dense during a rain fall

 

[KrisReef]

Rain does cause a drop in PH, I'm not 100% sure of the mechanism, but it must have to do with a change in local atmosphere composition. I notice high humidity has the same affect, just to a lesser extent. I think it increases the local concentration of CO2, either by causing stuff to gas off from the ground, or pulls co2 from the upper atmosphere down by disolving into the water as it falls and then gasses off.

Yup- Raindrops strip CO2 from the atmosphere and release it near the ground as the water reevaporates, causing near ground increases in atmospheric CO2. Op's intake must be getting elevated CO2 air during rainfall.

Rainwater collected during the intial rainfall will have elevated TDS and pH slightly lower that 7.