First time owning a pool!! Yesterday we put all the chemicals in to winterize our above ground pool. The directions said it would need to circulate for about 3 hours, then we could add the cover, turn off the pump, etc. About 2 hours into that, it started raining...and it hasn't stopped!! We totally should have checked the radar prior (hindsight is 20/20 am I right?!). And it looks like we've got 2 more days of rain.

Once this all clears, do you think we need to add more chemicals to the pool or do you think it'll be ok to finish closing (unhooking the pump, adding the cover, etc)?

Thanks in advance y'all!

  • 1
    What is the average depth of the pool? what depth of rain fell? what product did you use?
    – Jasen
    Sep 20, 2021 at 11:12
  • You know there are whole organizations that do nothing but collect and archive weather data, right? NWS, NOAA, numerous universities... all on the Web. One of the parameters they collect is "inches of rain". "An inch of rain" means if you set out a flat tray, the tray now has 1" of water in it from rain. This makes the math rather easy: If you know the average depth of pool in inches, and the number of inches of rain that fell, you can compute exactly how diluted it got. Sep 20, 2021 at 21:50
  • It's a 30ft above ground pool (I would assume 48 inches, simply based off my son's height). We received about 2 inches of rain so far.
    – mterry
    Sep 21, 2021 at 12:11

1 Answer 1


I suppose it depends on how "to the specs" you added chemicals. If enough water is added, the solution will be diluted and the effectiveness of the chemicals will be reduced. You need math here. You'll have to start with the concentration you were shooting for, determine how much water the rain added, and then work out the new likely concentration.

After that many days of rain, I have to suspect you'll be adding more. The question will be how much. If you've added an algaecide, you may not have to add a whole lot more of that. As for chlorine...well you can easily overdo that and it'll be ok.

  • What's the potential damage risk vs. the cost of re-winterizing?
    – jwh20
    Sep 20, 2021 at 13:22
  • @jwh20 It's not a question of damage, but one of "how badly to I want to avoid green water next spring?". Sep 20, 2021 at 14:26
  • I don't have a pool, but aren't there test kits to make sure you have the proper balance of treatments? I do have a hot tub and there are test kits for it. Sep 20, 2021 at 14:32
  • @GeorgeAnderson Sure, but most of the plain kits won't tell you about algaecide level, for instance. And winterizing tends to just be a "super shock" to ensure that you don't open in spring to a green sludge. Sep 20, 2021 at 14:34
  • I'll have to check with my husband about the kit he bought. It was a "dump and done" method (for lack of a better term). Cost isn't necessarily a factor; the kit was $45 ish. My main concern is having enough or having too much. We don't want green next year for sure, but also don't want to add too much for other unforseen reasons. And I don't think a testing kit would help due to this being a massive amount of chemicals added purposefully.
    – mterry
    Sep 21, 2021 at 12:15

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.