The Piedmont winter is a wet season with cold snaps, not a frozen one. That is good news for pool structures and less good for a closed pool, because rain keeps coming, the cover keeps collecting, and every warm week is a chance for the water to wake up. A closed pool is not a sealed pool. Here is what it needs between the closing and the opening.
Rain and the water level
A closed pool is usually lowered a few inches below the tile line or the skimmer, depending on the type and how it was closed. Over a wet winter, rain brings it back up. With a mesh safety cover, rain goes straight through and the pool fills. With a solid cover, rain sits on top unless a cover pump removes it, and if the pump fails or the cover sags, water runs in at the edges.
A pool that rises to the tile line in winter can crack the tile when the surface freezes and expands. A pool that rises into the skimmer can crack the skimmer. After a heavy rain, look. If the level is too high, pump it down with a submersible pump or the cover pump placed in the pool. Winterizing a pool in North Carolina explains why the level was set where it was.
Cover pumps
A solid cover needs a pump on top of it, and the pump needs to work. Check it after storms. A pump clogged with leaves or one whose float has stuck leaves a pond on the cover, which stretches it, strains the anchors and eventually puts water in the pool anyway. Clear the pump and the debris around it. Automatic pumps are worth having; manual ones are worth remembering.
Leaves and debris
Fall leaf drop goes on into December in the Piedmont, and oak leaves keep coming. On a mesh cover, leaves sit on top and break down, sending tannins through into the water; brush or blow them off. On a solid cover, they collect around the pump and in the low spots. Debris left all winter stains the cover and feeds whatever grows in the pool. Fall pool care covers the run-up to closing.
Warm spells and algae
January in North Carolina can deliver a week in the sixties. Under a mesh cover, with sunlight coming through and chlorine long gone, algae starts. It is slow in cold water, but by March a pool that had no chlorine since November can be green. Every few weeks, especially after a warm stretch, pull back a corner and look. If it is starting to tint, add chlorine, brush what you can reach and check again. It is far easier than opening a green pool. Opening your pool in spring is a much shorter job when the water is clear.
Ice
A skin of ice on a closed pool is normal and harmless to the pool. Do not break it; sharp edges can cut a liner or a cover. The risk from cold is in plumbing that holds water and equipment that was not drained. If the pool was closed with lines blown out and plugged, the cold snap is not a concern. If it stays open and running through winter, the freeze-protect function has to be set and the power has to stay on. Freeze protection covers the running-pool approach. A power outage on a freezing night is the scenario to have a plan for.
Chemistry through winter
A closed pool does not need to be balanced weekly, but it should not be left to drift for four months either. Check pH and chlorine every few weeks. Rain dilutes the water and lowers alkalinity; a heavy winter can leave the pool with almost no buffer by spring. A little chlorine during warm weeks and a check of alkalinity in late winter mean the opening starts from a reasonable place.
The cover itself
Check anchors and straps on a safety cover after wind. A loose strap lets the cover flap, which wears it and lets debris in. On a solid cover, check for tears and for water-bag or edge failures. A cover that has failed in February is a pool that is open to everything for two months.
The equipment pad
Glance at it. Leaves piled on the heater, a critter in the pump housing, a plug that has worked loose: winter is when these happen unnoticed. If the system is running with freeze protection, make sure the pump is actually coming on when it should.
A short winter checklist
- After heavy rain: water level, cover pump, cover edges.
- After wind: straps, anchors, debris.
- After a warm week: pull back a corner and look at the water; add chlorine if needed.
- Monthly: pH, chlorine, a look at the equipment pad.
- Late winter: alkalinity, and a plan for opening.
We build pools that are straightforward to close and open across the Triad, including Winston-Salem and Graham. Reach out for a free consultation if you are planning a build or a renovation.