Clearer water after rain?

Jun 4, 2012
Malvern, PA

I've just bought a house and moved in just over a week ago. The previous owner was in pool business for 30 years which he passed it down to his son. He showed me what to do which chemical and I've been following that.

When I tested it, CL and PH was pretty high(He advised me to shock the pool first day I moved in and then every 2 weeks and every one week during hot summer when it's in high use) I think CL was above 3 and PH was more than 8.3 which water seemed to clear to me. I decided to not to add anything to lower CL and PH so I just added water when level was low and left it after it rained(thinking that+sunlight will lower CL and PH) We had couple of rain and Thunderstorm recently. We had thunderstorm day before and yesterday morning before I head out for work, I just glanced at the pool and noticed leaves and other things in it. I figured I would have to clean and put some CL tablets when I come back home.

When I was at work, it rained again so I figured with everything that happened water wouldn't be that clear when I get back home. To my surprise when I came back home after work, other than leaves and other stuff in the pool that fell in during thunderstorm, water was clearer than ever. It could have just been that it was cloudy and water wasn't reflecting much sunlight because of that but I definitely noticed water was much clear than before. Not saying it wasn't clear before the rain and everything but just noticeably clearer after thunderstorm and rain. It's not clear now since I've brushed wall(white powdery cloud comes out when I brushed it. I think it maybe calcium from what I've been reading?)

Could this be because it was too high CL and PH before? When I tested yesterday, CL and PH was at normal range instead of way above 3 for CL and 8.3 for PH.


Mod Squad
TFP Expert
Platinum Supporter
LifeTime Supporter
In The Industry
Apr 1, 2007
Sebring, Florida
Welcome to the forum :lol: Generally, rainwater doesn't have much affect on your pool but you have a problem that needs immediate attention. You need to lower your pH into the 7's. pH should never be allowed in the 8's and yours has apparently been that way a long time. I suggest you lower it now.

Secondly can you post complete test result for FC, pH (after you lower it) and CH, CYA and TA? That would help us better help you.
Jun 4, 2012
Malvern, PA
Thank you for warm welcome and such a quick response. When I tested yesterday, CL and PH was in normal range although I can't give you exact number as I can't remember the number but I do remember it was in normal range. I'm not sure the testing kit(which previous owner had) has ability to test everything. I think it can test for chlorine, PH, Alkalinity and one other thing which I can't remember right now. I'll check what it can test once I go back home today.

Thank you again.


Mod Squad
TFP Expert
LifeTime Supporter
May 19, 2010
Tucson, AZ
:wave: Welcome :wave:

Define "normal range" for chlorine.

The required MINIMUM FC level could be anything between 1ppm and 7+ppm ... depending on your CYA (stabilizer) level.

A little reading in Pool School (button at upper right) will take a you long way to understanding your pool's chemistry.

Soon you should realize the importance of accurately testing your water and I have to recommend you order one of the suggested test kits now, so that you have it when you come to that realization.