So over the course of the year we've been remodeling the house and left the pool covered for the season. With winter approaching I'm curious to know if I should pump out all of the now green water remaining in the pool and replace it to the normal winter fill height with fresh water, or if I can just leave it until next year when we re-open the pool.

My primary concern is that the green untreated water will possibly permanently stain the liner of the pool. It's a 10k+ gallon pool and I wouldn't want to open it next season with an ugly green stain stuck at the level the water sat at all season this year.

Is that a valid fear? Or will it be fine remaining covered through the winter with the current water and opened next season without trouble?

  • 1
    I've never seen a swimming pool that benefited from less attention. I've seen a few that have clearly not.
    – user23752
    Commented Sep 5, 2014 at 2:21

1 Answer 1


There should be no permanent cosmetic damage unless you have something seriously wrong with your liner (in which case the damage is already done).

Replacing water is very rarely the solution for algae. In practice you can just leave it until next season. Of course make sure it's winterized — i.e., if you're in a freeze zone ensure all lines, pumps, and filters are clear of water; and pump the water level back down.

If it were me I'd probably also dump in a "winterizing" dose of KemTek 60% algaecide, and if you have any metal in your water or pool also a winterizing dose of stain preventer.

But there's nothing you can do to have clear water when you open it in the spring: It will have to be started up, vacuumed, balanced, etc.

  • Thanks that sounds like pretty solid advice, this is our first house with a pool so still learning as we go. Cheers!
    – Chris W.
    Commented Sep 7, 2014 at 20:28

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