Winterizing advice online is written for two climates that are not ours. The northern version assumes months of ice and tells you to shut everything down. The Florida version tells you to keep swimming. North Carolina sits squarely in between: we get real freezes, sometimes hard ones, but not a continuous winter of them, and the pool may sit in the 50s for weeks before a single overnight dip into the 20s.
That in-between climate is exactly why so many Piedmont pools get damaged. Homeowners either over-close and create a much harder spring, or under-close and lose a pump, a heater, or a section of plumbing to one bad night in January. Here is how to think about it, and what actually breaks when you get it wrong.
Why Hybrid Winterizing Is Common in the Triad
Two legitimate strategies exist here.
Full traditional close. Water level dropped, lines blown out and plugged, equipment drained, pool covered, everything shut off until spring. It is the safest option and it asks nothing of you all winter. It is what most Guilford County homeowners choose.
Hybrid or partial close. The pool stays full and the system stays operational, chemistry is set for low demand, and freeze protection runs the pump when temperatures drop. This keeps the water clear, makes spring opening trivial, and keeps a heated pool available on a warm winter weekend. It also means a power outage during a hard freeze is a real risk you are accepting knowingly.
Neither is wrong. What is wrong is the half-measure done by accident: a pool that was never properly closed and never properly protected.
Balance the Water Before You Close It
This step gets skipped constantly and it quietly costs the most. Whatever chemistry the water has on the day you close it is the chemistry that works on your plaster, tile, and equipment for months.
Balance before you cover, not after:
- pH and total alkalinity in range, so the water is neither aggressive nor scaling.
- Calcium hardness in range. Water low in calcium will pull it out of your plaster over a long winter, etching the surface.
- A proper closing shock and algaecide, circulated fully before shutdown.
- Filter cleaned. Do not leave organic debris fermenting in a filter for four months.
Corrosive water does not take a break because the pump is off. Months of contact time is how a good plaster finish gets ruined.
Lowering the Water Level (or Using Gizzmos)
Water expands as it freezes. Wherever it is trapped in a rigid space with nowhere to go, it becomes a wedge, and the rigid thing loses.
The skimmer is the classic casualty. Water sitting in a skimmer throat freezes, expands, and cracks the housing or the tile around it. Traditional practice is to lower the water below the skimmer mouths, usually just below the returns as well, so the upper plumbing is simply empty.
The alternative is a Gizzmo, a hollow, compressible tube that threads into the skimmer. It fills the void so ice has less room to work, and it is designed to crush rather than transmit force to the skimmer body. Gizzmos let you keep the water level higher, which is useful under a mesh safety cover. What you must not do is leave the water at operating level with an open, unplugged skimmer.
Blowing Out and Plugging the Lines
Underground plumbing is the expensive thing to get wrong, because fixing it means breaking concrete. Use a blower or compressor to push all water out of the suction and return lines, then plug each line at the pool so water cannot flow back in. Plugs go in the returns and the main drain line if applicable; the skimmer gets a plug or a Gizzmo. At the equipment pad, lines are opened and drained.
Then add non-toxic pool antifreeze to the lines. It is not a substitute for blowing them out; it is insurance for the water that clings inside the pipe. Use pool-rated propylene glycol only. Automotive antifreeze is toxic and does not belong near a pool.
Draining the Equipment
The equipment pad is where most freeze damage actually happens here, because it is above ground, exposed, and full of water in rigid housings.
- Pump. Remove the drain plugs, empty the strainer basket, and get the volute dry. A pump housing full of water on a 22-degree night will crack.
- Filter. Remove the drain plug. Pull, rinse, and dry-store cartridges. Set a multiport valve to a neutral or winterize position.
- Heater. Drain it. A heat exchanger is a dense array of thin metal passages and one of the most expensive things on your pad to replace. Do not assume it self-drains.
- Salt cell. Remove, clean, and store it indoors. Fit the dummy cell if you have one.
- Store the drain plugs in the pump basket so you can find them in April.
Freeze Protection If You Keep the Pool Running
On a hybrid close, your protection is not plugs and antifreeze, it is circulation. Moving water is dramatically harder to freeze than still water. Nearly every modern automation controller includes freeze protect: when the air sensor reads below a set threshold, typically around 35 to 38 degrees, it overrides the schedule and runs the pump regardless of the hour. Better systems also rotate valve actuators so spa and feature plumbing circulate too.
It works, and it is a strong argument for automation in this climate. Understand its one weakness: it depends on power. An ice storm that takes your power on the coldest night of the year takes your freeze protection with it. If you will not be around to react, close the pool traditionally. Freeze protect can be added to an older pool as part of modern pool upgrades.
Choosing a Cover
- Mesh safety cover. Anchored into the deck, rated to hold weight, the best answer if children or pets are around. Water and light pass through, so you will see some algae by spring, but there is no standing water to pump off.
- Solid safety cover. Same anchored strength, blocks light entirely, so the water opens far cleaner. It collects rainwater that must be removed with a cover pump or it becomes hundreds of pounds of dead weight.
- Winter cover (tarp style). Cheap, held down by water bags, blocks light. It is not a safety cover, will not hold a child, and tends to be a mess by March.
In the Triad, an anchored safety cover is the right call for almost everyone. The anchors sit in the deck, which means cover planning belongs in the decking and hardscape conversation during the build, not after the concrete cures.
What Actually Cracks, and Why You Should Not Drain the Pool
Freeze damage follows one rule: water trapped in something rigid, with nowhere to expand. That is why pump housings, filter tanks, heat exchangers, skimmer throats, and above-ground pipe elbows are the usual victims, and why properly drained equipment survives a night that would have destroyed it full.
Finally, the mistake that turns a maintenance problem into a catastrophe: do not drain your pool for the winter. A shell in the ground is fighting the groundwater around it, and the water inside is what holds it down. Empty it and hydrostatic pressure from saturated Piedmont clay can lift or float the structure, cracking it or popping it partially out of the ground. Our red clay holds water well, which makes this worse, not better. If a shell must ever be emptied for resurfacing or structural repair, that is a controlled job with the hydrostatic relief valve opened and the timing planned, and it belongs to a renovation crew, not a weekend.
If you want your pool closed correctly, or you inherited one and have no idea what shape the plumbing is in, request a design consultation and we will look at your equipment pad, your cover, and what your pool actually needs going into a Piedmont winter. Call Oasis Pools at (336) 471-0103.