How much does rainwater affect FC. I would expect a small drop if I don't have to backwash pool. But that all I would expect is this correct?
Rainwater affecting chlorine
- Thread starter Kellybbb
- Start date
f3justusc
Well-known member
I am to recall that if you are expecting a lot of rain you should raise your FC a little. Normal rainfall should have no impact if your numbers are right.
I'm not sure how many gallons your pool is, but generally unless it's a small monsoon rain doesn't affect the chemistry that much.
Funny thing is Im not sure on how many gallons my pool is. The way I figure it is length(18) x width(33) x average depth(5.25) x 5.9 its 18399 gallons. So that's the number I been working with. What my problem is that Im overseas and my pool is losing the FC every day which tells me the chlorine is being eating up. My wife is telling me that its from all the rain we been having. But I have learned better here. Unfortunately I have been trying to get her to start up the pool while I'm over here. Because I turned the hose off and declared the pool full right before she brought me to the airport
A single rainy day will have virtually no effect on your pool chemistry. Unusually heavy or persistent rains over a long period of time (like we've had lately) can cause some dilution in FC. But, odds are, that there is some other factor in play if you are losing a substantial amount of FC every day. Even with the heavy rains that we've had lately, it has been punctuated with periods of sun and that will cause some FC loss which is typical. I would run an Overnight Chlorine Loss Test test whenever a rain-free night is forecast just to get some insight as to what's going on.
Without test results it's hard to say. Did you add any stabilizer after you turned the hose off? The sun will eat up the chlorine without the proper amount of stabilizer.
No matter what, there is going to be FC loss every day. It gets burned off by sunshine and UV. So some FC loss is expected. Every pool is different, so dependiing upon specific circumstances, you can expect anywhere from 1-3 ppm loss per day.
Debris washed into the pool will increase chlorine demand. If you are getting enough rain that the pool is overflowing the fresh water dilution will lower FC as well. Just have her test daily and add chlorine as needed. If it is not raining, run an overnight test to see if anything else is going on.
I would also love an OCLT IF I could get my wife out of bed before 10. I am going to show her this thread so she might believe me that its not the rain. I have had her add CYA to the pool by using poolmath but I didn't let her put the full amount in so it has some but not what supposed to have. I can barley get her to use the ph test much less a CYA test. Iam going to just have her maintain till I get home in two weeks. Please keep your fingers crossed.
Normal rain is no issue, but 2" in half an hour (Thursday evening) will cause a big mess! Re-tested and chlorine was a bit low. Easy fix.
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