We're in mid-October here in NC and the water is sitting right around 62 degrees, but my teenagers are still insisting on using the pool on warmer days. I know the general rule is to close when temps consistently stay below 60, but I'm trying to figure out if there's any real harm in waiting another week or two if they're still swimming occasionally. My concern is that algae growth slows way down at these temps anyway, so as long as I keep the chemistry dialed in, I'm not sure what the rush is. Anyone close late in the Southeast and have a reason I should just pull the trigger now?
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Closing timing question - temps dropping but pool still in use
- Thread starter NC_Nick
- Start date
poolmom_sarah
New member
We went through this exact same debate last fall. My kids were still jumping in through mid-October and I kept pushing the close date back week by week. Honestly, at 62 degrees you're in a pretty reasonable holding pattern, algae-wise, as long as you keep up with the chemicals. That's the part that bites people - they start treating the pool like it's "basically closed" but they haven't actually closed it, so the sanitizer levels drift and then they open in spring to a swamp.
What I ended up doing was just dialing back how often I was adding chemicals but still testing twice a week and keeping chlorine where it needed to be. Not full active-season maintenance, but not ignoring it either. The bigger thing I watched was the pH because that can swing faster in cooler water than people expect. If your teenagers are actually getting in on the 70 degree days you still have coming, there's no reason to rush the close just to have to partially reopen it for one last swim. I'd say keep an eye on your 10-day forecast and when you stop seeing any days that would realistically get them in the water, that's your window to close. Chasing that last swim is not worth pulling the cover back off.
What I ended up doing was just dialing back how often I was adding chemicals but still testing twice a week and keeping chlorine where it needed to be. Not full active-season maintenance, but not ignoring it either. The bigger thing I watched was the pH because that can swing faster in cooler water than people expect. If your teenagers are actually getting in on the 70 degree days you still have coming, there's no reason to rush the close just to have to partially reopen it for one last swim. I'd say keep an eye on your 10-day forecast and when you stop seeing any days that would realistically get them in the water, that's your window to close. Chasing that last swim is not worth pulling the cover back off.
Nick, the 60-degree threshold is a guideline, not a hard cutoff. The real number that matters for algae is closer to 50 degrees - below that, most algae strains essentially go dormant. At 62 you're in a gray zone, but like Sarah said, the chemistry has to stay active. The thing people miss is that the bather load drops off so they stop testing as often, then they get a surprise when they finally go to close.
If the kids are still getting in a few times a week, keep your FC in the upper range of whatever your CYA demands and test twice a week minimum. Phosphate levels creeping up during the shoulder season is a real thing too, especially with leaves starting to drop, so keep an eye on that. One thing I'd actually watch more than algae is your equipment. Running the pump in colder weather isn't the issue, but if you're in a part of NC that could see a surprise freeze overnight, you want to be ready to close on short notice rather than scrambling.
My personal habit in a similar climate was to set a firm mental deadline - something like "if we hit two consecutive nights below 38 degrees, we close that weekend regardless of who wants to swim." Takes the debate out of it and gives you time to get the chemicals right before closing rather than dumping everything in last minute.
If the kids are still getting in a few times a week, keep your FC in the upper range of whatever your CYA demands and test twice a week minimum. Phosphate levels creeping up during the shoulder season is a real thing too, especially with leaves starting to drop, so keep an eye on that. One thing I'd actually watch more than algae is your equipment. Running the pump in colder weather isn't the issue, but if you're in a part of NC that could see a surprise freeze overnight, you want to be ready to close on short notice rather than scrambling.
My personal habit in a similar climate was to set a firm mental deadline - something like "if we hit two consecutive nights below 38 degrees, we close that weekend regardless of who wants to swim." Takes the debate out of it and gives you time to get the chemicals right before closing rather than dumping everything in last minute.
Same boat here last year, almost exactly. I'm in Virginia so similar weather patterns to NC, and my son kept lobbying hard to keep it open through October. We ended up closing the second week of November and I was testing and dosing the whole time we kept it open, which looking back was the right call but also kind of a pain.
The thing D Hartley said about bather load is real. When it's cold and the kids only get in twice a week instead of every day, you kind of start eyeballing the chemicals instead of actually testing. That's where I slipped up toward the end - I figured "nobody's really using it, how bad can it be" and skipped a couple tests. Water looked fine but when I finally tested it, chlorine had drifted pretty low. Nothing catastrophic but it was a reminder that the pool doesn't care how often you're swimming in it.
If your teenagers are still actually getting in on the warmer days, my honest take is just treat it like normal season. Test twice a week, keep your free chlorine where it needs to be, and close when they finally give up on it or the temps make the decision for you. The only thing I'd add is to keep an eye on phosphates going into closing since fallen leaves this time of year can spike them fast, and you dont want to deal with a green pool in the spring.
The thing D Hartley said about bather load is real. When it's cold and the kids only get in twice a week instead of every day, you kind of start eyeballing the chemicals instead of actually testing. That's where I slipped up toward the end - I figured "nobody's really using it, how bad can it be" and skipped a couple tests. Water looked fine but when I finally tested it, chlorine had drifted pretty low. Nothing catastrophic but it was a reminder that the pool doesn't care how often you're swimming in it.
If your teenagers are still actually getting in on the warmer days, my honest take is just treat it like normal season. Test twice a week, keep your free chlorine where it needs to be, and close when they finally give up on it or the temps make the decision for you. The only thing I'd add is to keep an eye on phosphates going into closing since fallen leaves this time of year can spike them fast, and you dont want to deal with a green pool in the spring.
The bather load point is worth repeating because it catches a lot of people off guard. When usage drops to once or twice a week, it's easy to go 10 days without really looking at the water, and that's when you get behind on things. Your free chlorine can drift lower than you think even in cooler temps if you haven't adjusted your output for the lighter use.
What I'd do in your position is keep testing at least twice a week regardless of whether anyone swam, and maybe dial back your chlorinator a bit since the demand drops with the temperature and lighter traffic. Two or three more weeks in NC at 62 is pretty manageable as long as you stay on top of it. The risk isn't usually algae at that temp, it's just neglect sneaking up on you.
What I'd do in your position is keep testing at least twice a week regardless of whether anyone swam, and maybe dial back your chlorinator a bit since the demand drops with the temperature and lighter traffic. Two or three more weeks in NC at 62 is pretty manageable as long as you stay on top of it. The risk isn't usually algae at that temp, it's just neglect sneaking up on you.
following this thread because i'm in almost the same spot, first year owning a pool and not sure when to pull the trigger on closing. one thing i did pick up from someone at my local pool store was to throw in an algaecide as kind of a buffer while you're in that in-between period - i've been using the aquadoc one i found through mavaquadoc.com and it seemed to help me feel less anxious about stretching things out a bit. that said i'm definitely not the right person to advise on the chemistry side, so i'm mostly just reading what d hartley and nroberts are saying and taking notes.