Pool after a storm

Jun 10, 2011
53
SE Michigan
We got a big storm Wednesday night that turned my crystal clear pool into a hazy green mess when I checked it yesterday. so much rain that it filled my pool to the brim and I had to backwash for a few minutes to bring the water level back down 3-4 inches. I couldn't even see the bottom of the deep end. we got more rain last night and I had to backwash again this morning. the pool had a definite green tint to it.

my questions are:

is it normal for a storm to turn a clear pool this dirty looking and green?

what do you do to clear this up quickly?


my normal routine is to bring my FC to 7 at the end of each day. it falls down to 3.5 -4 most days before I add more bleach. my CYA has been hanging around 40. last night, I added a little more bleach to bring it up to 8 but then it poured rain again. FC this morning was 7 even with the extra water in the pool so I believe I passed the OCLT. CC was <.5 as well, so I don't think I need to shock the pool. I vacuumed yesterday and added chlorine, turned the filter up a little and let it run overnight. I added a little more chlorine this morning. is there anything else I can do other than up the FC level a little and wait 2-3 days for this to clear? the last big storm it took about 3 days to clear up. I'd like it to be clear and blue again for the hot weekend.

I think that we got so much rain that some of it goes from my retaining wall into the pool and pulls in some dirt with it. there was alot of dirt on the steps that I could see both yesterday and today that I brushed off each time.

also, is there any reason kids couldn't swim in what looks like green, hazy water?
 
A LOT of rain will do that if your FC had drifted towards the lower end of the spectrum...........you hadn't added any more chlorine yet........and then the bottom fell out. Not so much if it had been "recharged" to target levels before.
 
woodyp said:
A LOT of rain will do that if your FC had drifted towards the lower end of the spectrum...........you hadn't added any more chlorine yet........and then the bottom fell out. Not so much if it had been "recharged" to target levels before.


My FC was brought up to 7 on Wednesday night. It rained all night and filled up the pool, which I saw when I got home yesterday. I pulled off the solar cover to reveal the dirty, hazy, greenish pool. I checked the FC level and it was still at 5. I backwashed to lower the water level, vacuumed the pool, put in more bleach to raise the FC to 8, raised my filter rmp to 2100 and let it run all night. It rained again last night and filled the pool again. Pool still had the same greenish tint. I again lowered the water level and tested FC, which was at 7 and CC was <.5. I added a little more bleach to bring FC up to 8-8.5 for the day. I upped my filter speed again to 2200 and I'm hoping things will be a little better when I get home from work. but like I said, the last time it took a few days. is this normal? asked another way, do other pools go from crystal clear to incredibly dirty from a heavy rainstorm? and is there anything else I can do to help clear it up faster?
 
Bama Rambler said:
I agree that you're going to need to shock. If you want to prove that you can run the OCLT tonight.

I ran it last night and seemingly passed.....I will do it again tonight to be sure

can a overnight rainstorm take a perfectly clear pool and turn it into something that needs to be shocked? even if my FC never fell below 5 with a CYA of 40? I'm confused as to how this could happen....

also, this happened a few weeks back when we had a pretty good rain (even threw some furniture into the pool :shock: ). that time, I did what I was planning on doing this time, just make sure my FC levels are ok, and it eventually cleared up in 3 days. I didn't shock it then as I never had a CC reading over .5 and passed the OCLT. assuming there was something in there, is it possible to clear it up without shocking as I somehow did?

my original post was just to find out what a big rainstorm will do to a pool as far as making it murky and also what to do to help it clear faster. I take it from the lack of answers that this is not normal and that there really is no way to speed up the recovery other than shocking.
 
If you passed the OCLT then you don't need to shock just raise the FC to the top of the recommended range and let the filter take care of it.

Most of the time rain won't affect a pool too much but if dirt or debris rains or blows in it can affect it a good bit.
 
Bama Rambler said:
If you passed the OCLT then you don't need to shock just raise the FC to the top of the recommended range and let the filter take care of it.

Most of the time rain won't affect a pool too much but if dirt or debris rains or blows in it can affect it a good bit.

as far as the OCLT, I went from 8 to 7 but did have quite a bit more rain too so thought that may have accounted for part of the 1 ppm that was lost.

I came home from work and the pool had a definite green tint to it so its gotta be something. I added enough chlorine to get up to 16 ppm shock level for 40 CYA. Is there any downside to shocking if its not needed? I didn't think so, so I went ahead with it.

I do get quite a bit of dirt blown in to the pool during storms it seems. trying to remedy that for the future.
 
and when it rains, it pours (pun intended). I was running low on test kit supplies so I ordered the complete refill set. almost out of the R-0870 powder for the chlorine test, so I opened up the package today and, of course, every single item is in there but this one. I have to do a bunch of chlorine tests for my shocking process and have enough powder to do 2 tests maybe.

called TFTest Kits but get a machine every time. left a message about my emergency to see if they could help me out, but no call back yet.
 

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FC = 11.5 as of 9:00 tonight, down from what should have been 16 at around 3:00. I put in 126 oz of bleach to bring it back up to 16. I didn't retest it due to the low R-0870. I'll retest in the morning for FC loss assuming I was at 16.

the pool looked to be turning more of a cloudy white from the greenish tint so I'm hoping for it to be clearer by morning.

what are the rules for swimming during the shocking process? at what point can I allow kids to swim?
 
FC was at 13.5 at 9:00 am.
CC <.5

I added 32 oz of chlorine to bring it back around 16. I can't tell for sure if I failed the OCLT as I couldn't test it last night. the water is still more cloudy than green at this point. I still can't see the bottom of the 6'6" deep end.

supposed to be over 90 today so we'll probably be hopping in this afternoon. I'm under the impression that this is just my sand filter being slow. I'm not sure what I'm going to do going forward. I can't have the pool like this for 3 days after every storm we get.
 
questions I still have that are unanswered:

1. can you get an algae outbreak with FC not lower than 5 (CYA 40)? not even sure if this is possible
2. can algae clear up and go away without shocking? I didn't shock last storm and whatever was causing my cloudiness did go away
3. is there any downside to shocking if its not needed? if you do it, just to be on the safe side
4. when can you swim during or right after shocking? what am I looking for before I allow kids to swim?


if anyone wants to take a stab at these, I'd appreciate it.
 
judge smails said:
questions I still have that are unanswered:

1. can you get an algae outbreak with FC not lower than 5 (CYA 40)? not even sure if this is possible
Yes, if it was never cleared up in the first place.

2. can algae clear up and go away without shocking? I didn't shock last storm and whatever was causing my cloudiness did go away.
No, but it can be invisible and make you think it's gone away.

3. is there any downside to shocking if its not needed? if you do it, just to be on the safe side.
Some pool owners may increase FC in anticipation of a pool party. I don't shock if it isn't needed.

4. when can you swim during or right after shocking? what am I looking for before I allow kids to swim?
I don't swim during shocking of if the pool is murky/cloudy in anyway.


if anyone wants to take a stab at these, I'd appreciate it.

Lastly, if the cloudiness is persistent and consistent, I'd increase my filter run time to 24/7 for a day or two.
 
ivyleager said:
judge smails said:
questions I still have that are unanswered:

1. can you get an algae outbreak with FC not lower than 5 (CYA 40)? not even sure if this is possible
Yes, if it was never cleared up in the first place.

2. can algae clear up and go away without shocking? I didn't shock last storm and whatever was causing my cloudiness did go away.
No, but it can be invisible and make you think it's gone away.

3. is there any downside to shocking if its not needed? if you do it, just to be on the safe side.
Some pool owners may increase FC in anticipation of a pool party. I don't shock if it isn't needed.

4. when can you swim during or right after shocking? what am I looking for before I allow kids to swim?
I don't swim during shocking of if the pool is murky/cloudy in anyway.


if anyone wants to take a stab at these, I'd appreciate it.

Lastly, if the cloudiness is persistent and consistent, I'd increase my filter run time to 24/7 for a day or two.


thanks!!

1. the pool was as clear as possible for the last 3 weeks or so. prior to that, I had some slight cloudiness due to the new plaster the first couple weeks the pool was open. since then, its been very clear. not sure if this means, it was cleared up or not. could it have been invisible all of this time? if it matters, I've never had a CC reading of >.5 ever, even in the last couple of days.

2. the last storm was 3 weeks ago or so. it was very cloudy and greenish. after a few days, the filter cleared it up and it was crystal clear since then until this last storm.

3. so no downside?

4. I did some more searching this morning and read that you can swim as long as you're below shock level.

edited to add: my filter has been running 24/7 since the pool opened.
 
ivyleager said:
You can do whatever you feel is best.

I'll add that I've had algae outbreaks before (including mustard algae) in which CC was NEVER over 0.5 and a few readings of 0.0. Don't know how that is possible, but it was.

I was wondering this myself. I assumed that if my FC was breaking down algae, that my CC would read over .5. it never has, so I always thought I was good on that front.

pool is turning more blue from the greenish blue tint of yesterday. still cloudy though, but I'll monitor it over the next day or two to see how long my filter takes to clear it up.


still confused as to why it turned greenish in the first place and if I even had an algae problem. I'd like to be running more frequent tests but I'm out of luck with very little R-0870 powder
 
How long has it been since you checked the CYA? If you have had overflow due to rain and also had to lower the water level in the pool you may have lost a significant amount of CYA, causing the FC to burn off more quickly.
 

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