Is it necessary to add algaecide when closing the pool
- Thread starter syedsam
- Start date
John Faulkner
Member
I skip it and just do a strong shock right before closing never had a problem so I’d say it’s optional depends how much peace of mind you want.
Ella Robinson
Member
I usually do a strong shock the day before covering and balance the water that’s enough for me. If you want extra peace of mind (or it’s still warm), add a non-foaming polyquat algaecide per the label. Totally optional
Alma Weber
New member
In my opinion, if the water’s still warm or you want a little extra protection, adding some polyquat is fine. But skipping it is usually totally fine too.
Michael Williams
New member
If you’re closing when the water is consistently cold and the pool is truly clean, it’s usually enough to dial in pH/alkalinity, make sure sanitizer is in a safe range, circulate a bit, and cover. Adding an algaecide is more of an “insurance policy” when you’re closing while it’s still relatively warm, the cover lets in more light, or you expect more organic junk to get in over winter. So it’s not mandatory, but if you tend to open to musty/slimy water, it can be an extra layer on top of the real basics that matter most: remove organics before closing and don’t close with low sanitizer.
Henry Graham
Member
I went back and forth on this for a few seasons because some closing guides make it sound mandatory and others barely mention it. What I noticed over time is that the condition of the water when you close matters more than whether you add algaecide.
If the pool is really clean, the pH and alkalinity are stable, and you close once the water temperature drops into the upper 50s or lower, algae usually doesn’t have much opportunity to grow anyway. Cold water slows everything down a lot. The bigger mistake I made early on was closing while the water was still warm and there was still some organic debris in the system. Even with chemicals, that can cause problems under the cover.
Now I focus more on circulation and filtration the day before closing. I let the pump run long enough for the filter to grab anything still floating around and I check that the filter pressure is normal so I know flow through the system is good. Starting winter with clear water and a clean filter seems to make the biggest difference when opening.
Algaecide can still act like insurance, especially if you’re closing a little early or using a cover that lets in light. But if the water is cold, balanced, and free of organics, it usually isn’t the deciding factor. I’ve had some of my easiest spring openings in seasons where I skipped it but closed with really clean water.
If the pool is really clean, the pH and alkalinity are stable, and you close once the water temperature drops into the upper 50s or lower, algae usually doesn’t have much opportunity to grow anyway. Cold water slows everything down a lot. The bigger mistake I made early on was closing while the water was still warm and there was still some organic debris in the system. Even with chemicals, that can cause problems under the cover.
Now I focus more on circulation and filtration the day before closing. I let the pump run long enough for the filter to grab anything still floating around and I check that the filter pressure is normal so I know flow through the system is good. Starting winter with clear water and a clean filter seems to make the biggest difference when opening.
Algaecide can still act like insurance, especially if you’re closing a little early or using a cover that lets in light. But if the water is cold, balanced, and free of organics, it usually isn’t the deciding factor. I’ve had some of my easiest spring openings in seasons where I skipped it but closed with really clean water.
Katherine Morgan
Member
I used to treat algaecide like a required step too, mostly because a lot of closing guides bundle it into the process. After a few seasons I realized the bigger factor was always the condition of the water when the cover went on.
The year I had the worst spring opening was actually when I did use algaecide, but I closed a little early while the water was still warm and there were leaves breaking down in the pool. By spring the water had that dull green tint and the filter pressure climbed fast once I started circulating again. Ever since then I’ve focused more on getting the pool really clean before closing, running the pump long enough that the filter grabs the last bits of debris, and making sure the balance is steady before shutting things down.
Now I usually wait until the water temperature drops quite a bit before closing. Cold water slows algae growth so much that it becomes less of a factor over winter. If the pool is clear, the organics are removed, and circulation has been good before the cover goes on, that seems to matter more than whether an extra bottle goes in at the end.
That said, I can see why some people still use it as insurance, especially if they have to close while the water is still relatively warm or if their cover lets in more light. For me the biggest difference has always been starting winter with really clean water and normal filter pressure rather than relying on extra additives. Anyone else notice the spring opening is easier when the pool is closed later in the season?
The year I had the worst spring opening was actually when I did use algaecide, but I closed a little early while the water was still warm and there were leaves breaking down in the pool. By spring the water had that dull green tint and the filter pressure climbed fast once I started circulating again. Ever since then I’ve focused more on getting the pool really clean before closing, running the pump long enough that the filter grabs the last bits of debris, and making sure the balance is steady before shutting things down.
Now I usually wait until the water temperature drops quite a bit before closing. Cold water slows algae growth so much that it becomes less of a factor over winter. If the pool is clear, the organics are removed, and circulation has been good before the cover goes on, that seems to matter more than whether an extra bottle goes in at the end.
That said, I can see why some people still use it as insurance, especially if they have to close while the water is still relatively warm or if their cover lets in more light. For me the biggest difference has always been starting winter with really clean water and normal filter pressure rather than relying on extra additives. Anyone else notice the spring opening is easier when the pool is closed later in the season?