How does rain water affect PH? Recently we have had alot of rain and have been pumping the pool out every couple days. My PH seems much more stable with the rain then when not raining. Why is this?
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How does rain water affect PH? Recently we have had alot of rain and have been pumping the pool out every couple days. My PH seems much more stable with the rain then when not raining. Why is this?
Depends on where you are. Here in NY, the rain is quite acidic, below what you can test on the normal phenol red test, so it is below 6.8. If you get enough rain, it can definitely drop (or counter a natural rise) your PH.
Funny you have observed this!!! During some of the thunderstorms we had this summer I was noticing that my ph and alkalinity would fall off the chart. We had a 5+" rain overnight the other night and I woke up to water levels above the skimmers. My first thought was that this would be an ordeal to get things back in order. I dumped about 3" of water from the pool with the pump and however much went out the overflows during the night, added some chlorine to get the cl back up and that was it. Ph was at 7.5 and alkalinity was at 70 while cya stayed in at below 30. This surprised me because I figured that on a 20x40 Ig pool I probably pumped out several thousands of gallons to get out 3" of water. Maybe it was not as much as I figured and the overnight rainfall has a different effect than a thunderstorm during the daylight hours.
Not being a climate guru I can believe rain chemistry is very dependant on the local area. Chemical and power plants, big city with lots of vehicles, etc. Here in rural Northeast PA I periodically measure the pH of rainwater and it is always as close to 7.0 as I can measure with a pool test kit. The only effect I have ever seen, even after many inches of rain, is smple dilution. I catch rain from gutters when I need to top the pool. I love it.
Al
Al is correct about pH of rain water being dependent on local area. I have measured the pH of rain water from the area where I work and home. I commute about 45 miles and have noted a pH at work around 5.0 and at home around 7.0. There is a coal power plant not far from the hospital and it causes a lower pH in rain water. I have also noted a variance in rain pH when the storms come from different directions at home. I have a rain gauge on my deck and plot rain fall and check pH each time I dump it. Next year I also plan to add ALK to the measurements to compare rain pH and ALK to pool pH and ALK.
Steve
All that would make sense to me because thunderstorms could come from an area around here that had a paper plant or industrial boiler but any weather that came from the north would come from a national forest. Thus one weather event might produce a very different ph than another. Then again what do I know!! My handle is "chemistrydropout". But I'm learning. I have found that if I test the water and keep the chemicals on hand it doesn't really matter that much. It is scary though when you check the water and it is off the ph scale, very little or no chlorine, and alkalinity is out of whack. Panicky might be a better word. This happened during one heavy rain event this summer. At least this week I knew to check things out the morning after instead of waiting till the normal afternoon test routine.:rolleyes:
Here in Hawaii the pool is kept at 7.5. When it rains the pH jumps up depending on how long it rains for.
Aloha