Winterization and Freeze-Thaw Care in Connecticut

When to close

The closing window in Connecticut runs roughly mid-October to early November, once water temperatures consistently drop below 60 degrees. Close while the water is still warm and algae grows under the cover all winter; close too late and a hard freeze can arrive before the equipment is drained. Closing-season schedules fill fast in October, so book the closing in September.

What a proper closing does

• Balances the water first. pH, alkalinity, and calcium are adjusted before closing so the water does not scale or corrode surfaces over the winter, then winterizing algaecide and shock go in.
• Lowers the water level. Typically to a few inches below the skimmer, so ice movement does not damage the skimmer or lift the liner.
• Blows out and plugs the lines. Every return line, skimmer line, and cleaner line is blown clear with air and plugged, and antifreeze goes into the lines. Water left in plumbing is where freeze damage starts.
• Drains the equipment completely. Pump, filter, and heater are drained — heater heat exchangers are especially vulnerable, and a single freeze can crack a manifold that costs hundreds to replace.
• Secures the cover. A taut, anchored winter cover keeps out leaves, debris, and rainwater, and keeps the water chemistry stable until spring.

What freeze damage actually costs

Water expands when it freezes, and it does not negotiate. Water left in pipes, pump housings, or filter tanks cracks PVC fittings, splits pump housings, and fractures filter tanks — a single freeze event can produce $1,000 to $3,000 in equipment damage that a thorough closing would have prevented. A light frost on a full pool is rarely a disaster; an overnight hard freeze on undrained equipment is.

What not to do

Do not drain the pool. The water left in the pool — tens of thousands of gallons, weighing over a hundred tons — is what holds the walls and floor in place against the earth around them. Draining a pool for winter risks the ground pushing the walls in or lifting the shell, and it ruins vinyl liners. What comes out is the water in the plumbing and equipment; what stays is the water in the pool.

Fiberglass, vinyl, and concrete in winter

Fiberglass handles winter best: the shell flexes with ground movement and the gelcoat resists the staining and algae that plague rougher surfaces under a cover. Vinyl needs careful water-level management, because ice movement and low water can wrinkle or float a liner. Concrete needs the most vigilance: any crack or tile defect that lets water behind the surface becomes a freeze-thaw wedge by spring. Whichever you own, the closing checklist is the same — the material only changes how much forgiveness you have when it is skipped.