How to winterize an inground pool in Ohio

Because our winters freeze and thaw over and over. Water expands by about 9 to 10 percent as it freezes, as Latham's winterizing guide notes, and a pipe, pump housing or heater exchanger full of water will crack when it does. A single hard freeze can do it. Northeast Ohio gives you many chances: our count of NOAA daily records for 1996 to 2025 found an average of about 71 days a year at Akron-Canton Airport where the temperature crossed freezing in both directions, and about 85 at Chardon.

Every one of those cycles works on any water left where it should not be. A proper winterization removes that water from the plumbing and equipment, leaves the right amount in the pool and puts a cover on that keeps kids, pets, leaves and snow out until spring.

Before the first hard freeze, and with some margin. NOAA's 1991 to 2020 normals put the median first fall temperature of 32 degrees on October 26 at Akron-Canton Airport, October 29 in Ravenna, November 3 at Cleveland Hopkins near the lake and October 18 in Chardon. Those are medians, so in about half of years the first freeze comes earlier. A harder freeze of 28 degrees has a median date of November 7 at Akron-Canton and November 1 in Chardon.

In practice many owners in the Akron, Canton and Kent area close from late September to mid-October, and snowbelt owners in Geauga and inland Lake County close earlier. If you have a heater and want to swim late, keep the pump running through any early cold snap so water keeps moving in the lines, and book your closing before the forecast turns rather than after.

Start a few days ahead. Test and adjust pH, alkalinity and calcium hardness, then shock the pool and let the filter run. Balanced water through the winter protects the surface and makes the spring opening easier. For a fiberglass pool, Latham's Liberty warranty lists target ranges including pH 7.2 to 7.6, total alkalinity 80 to 120 ppm and calcium hardness 250 to 350 ppm. AQUA Magazine's guidance for fiberglass winterizing adds that no extra chlorine is needed if chemistry is in range and that calcium hypochlorite products can cause problems on fiberglass, so use liquid chlorine or a non-chlorine shock if levels are low.

Then skim, brush and vacuum. Anything left on the floor sits there for six months and can stain. Clean the skimmer and pump baskets and remove ladders, rails and anything else that comes out.

This is where pool type matters most. Latham's winterizing guide is blunt: never fully drain a swimming pool, and in most cases it is safe to lower the water about an inch below the skimmer. Follow your pool manufacturer's instructions and your cover maker's instructions on the exact level.

• Fiberglass. Be conservative. Latham's Liberty warranty says the pool is designed to stay full and is voided by failing to keep the water above the skimmer outlet. AQUA Magazine's fiberglass guidance is to lower the water only to the bottom of the skimmer and never below. Some owners skip lowering entirely and use a skimmer plug or cover plate instead. On our wet clay soils, an overly low fiberglass pool is at real risk of bulging or lifting.
• Vinyl liner. Lower only to just below the skimmer. A liner needs the water's weight to stay in place, and draining it can let the liner shrink or shift.
• Concrete, including ICF. Lower to just below the skimmer or as the finish requires. Never drain a concrete pool for winter either. Groundwater can lift an empty concrete shell too.

Lowering the water does not protect the underground pipes. Latham's guide says to blow the water out of the pump, pipes, hoses and any vessel that holds water. That means using a blower or compressor to push air through the skimmer lines, returns and main drain line until no water is left, then sealing each line with winterizing plugs at the pool end. The main drain line is usually protected by blowing air through it and closing it off so an air lock keeps water out.

Some service companies also add pool antifreeze to the lines as a backup. Either way, the goal is the same: no standing water in any pipe that sits in freezing ground. A skimmer freeze-protection device, often called a Gizzmo, is worth adding even with a plug, because melting snow and rain can refill the skimmer throat during a thaw.

• Pump. Remove the drain plugs, let it empty and store the plugs in the pump basket so they are easy to find in spring.
• Filter. Clean a DE filter thoroughly, drain the tank and leave the drain open. Our packages include a Pentair DE filter.
• Heater. Drain it completely per its manual. A heat exchanger with water left inside is one of the most expensive things to crack in a pool system.
• Salt cell, chlorinator, automation. Drain or remove as their manuals say, and shut off power to the equipment at the breaker.

If any of this sounds unfamiliar, it is worth paying for a professional closing at least the first year and watching how it is done.

Every extra with water in it needs the same treatment as the main pool. An attached or spillover spa has its own suction and return lines, and often jets and an air blower line, and each must be blown dry and plugged. Leave the spa water at the level its maker recommends, and never assume the spa is protected because the pool is. Sheer descents, bubblers and waterfalls have supply lines that sit near the surface, which makes them among the first things to freeze. Blow them out and plug them too.

Automation panels, timers and remote sensors should be shut down per their manuals. A salt chlorine generator cell is usually removed, cleaned and stored indoors. If you have an automatic cover, check the cover maker's guidance on winter use, keep the cover box drained where it has a drain and do not run the motor with ice on the fabric. Finally, write down what was done and where each plug and part is stored. In April that list saves an hour of hunting, and it tells whoever opens the pool what was done in the fall.

A winter safety cover anchored into the deck is the standard in our area. Latham's guide says to seal the edge so wind cannot get under it. Liberty's cover page describes the two main types:

• Solid safety covers block all sunlight and keep out fine debris, so the water is cleaner in spring. Rain and snowmelt collect on top, so you need a cover pump to remove standing water.
• Mesh safety covers let water drain through and cost less up front. Fine dirt comes through with the water, and the pool level rises over winter, so plug the skimmer well.

An automatic cover is not a winter cover on its own in most cases. Follow the cover maker's guidance on whether it can stay closed through snow.

Look at the pool after every major thaw and heavy rain. With a solid cover, pump off standing water so the cover is not overloaded. With a mesh cover, watch that the water does not rise into the skimmer. On a fiberglass pool, make sure the level has not dropped from a leak. If snow drifts heavily onto one side of the cover, clear what you safely can, but do not walk on the cover.

In the snowbelt, where Chardon averages more than 110 inches of snow a year in NOAA's normals, check more often. Heavy, wet late-season snow is the hardest load a cover sees.

Plenty of owners learn to close their own pool, and the steps above are the core of it. The parts people most often get wrong are the water level on fiberglass pools, leaving water in the heater and not blowing the lines long enough. A mistake shows up in April as a cracked fitting, a split pump housing or a stained floor.

We do pool closings and openings as part of our service work, including water balancing and equipment checks. If you would rather learn, ask us to walk you through it the first year.