How do I prevent my Ottawa pool skimmer basket from cracking during early frost?

The key to preventing your Ottawa pool skimmer basket from cracking during early frost is to ensure the water level in the skimmer is lowered below the bottom of the skimmer opening before freezing temperatures arrive, and to install a winter gizzmo (freeze plug) in the skimmer throat to absorb ice expansion pressure. A gizzmo costs $8 to $15 per skimmer and is one of the least expensive yet most important winterization components for any Ottawa pool.

Ottawa's unpredictable fall weather makes skimmer protection a genuine concern. While the official pool closing season runs from late September through mid-October for most Ottawa pool companies, early frost events are not uncommon in September — Environment Canada data shows overnight temperatures at the Ottawa International Airport weather station dropping below 0°C as early as mid-September in some years, with the average first frost date falling around September 28 to October 5 depending on your specific neighbourhood. Pools in lower-lying areas of Orleans, Kanata South, Barrhaven, and along the Ottawa River tend to experience frost earlier than elevated neighbourhoods like Westboro and Alta Vista due to cold air pooling in the valley.

Understanding why skimmer baskets crack requires understanding how water freezes in a confined space. Water expands approximately 9 percent when it freezes. Your pool skimmer is essentially a rectangular box molded into the pool wall, with the basket sitting inside it. If water remains at or above the skimmer basket level when the temperature drops below freezing, the water inside the skimmer body freezes and expands against the basket walls. The plastic basket, confined within the rigid skimmer body, has nowhere to flex and cracks under the expansion pressure. The basket itself is a relatively inexpensive replacement at $15 to $40, but the skimmer body behind it is built into the pool wall and costs $500 to $1,500 to replace if it cracks — a repair that requires excavation around the outside of the pool.

The gizzmo is the standard solution used by every professional pool company in Ottawa. A gizzmo (also spelled "gizmo") is a hollow plastic cylinder threaded at the bottom that screws into the skimmer's drain hole after the basket is removed. The hollow body compresses when ice forms around it, absorbing the expansion force that would otherwise crack the skimmer body. Think of it as a sacrificial shock absorber — the gizzmo deforms slightly to protect the rigid skimmer housing. After removing the skimmer basket for winter, lower the pool water level to 10 to 15 centimetres below the bottom of the skimmer opening, then screw the gizzmo into the skimmer drain fitting and apply Teflon tape to the threads for a tight seal. The gizzmo should stick up above the top of the skimmer opening so it remains visible under the winter cover.

If you have not closed your pool yet and an early frost warning appears in the Ottawa forecast, take these immediate steps. First, remove the skimmer basket entirely — a cracked basket is annoying but inexpensive, while a cracked skimmer body is a major repair. Second, if you have a gizzmo on hand, install it immediately. Third, if you do not have a gizzmo, place a tightly sealed plastic bottle (like an empty 2-litre pop bottle) filled halfway with pool antifreeze into the skimmer throat — it provides some compression space for ice expansion as a temporary measure. Fourth, pour pool-grade antifreeze directly into the skimmer until it fills the plumbing line below — this prevents the pipe running from the skimmer to the pump from freezing and cracking, which is an even more expensive repair at $300 to $1,000 or more.

Ottawa pool owners who keep their pools open into October for late-season swimming need a frost management strategy. Running your pool pump continuously on nights when the forecast calls for temperatures between -2°C and 0°C keeps water circulating through the skimmer and prevents ice from forming. Moving water requires sustained temperatures below approximately -5°C to freeze, and most September and early October frost events in Ottawa are mild, brief overnight dips that a running pump can easily handle. However, if the forecast predicts sustained temperatures below -3°C or lower, circulating water alone is not sufficient — at that point, you should either close the pool or lower the water level below the skimmer as a precaution.

The quality of your skimmer basket affects its frost resistance. Bargain replacement baskets made from thin, brittle polypropylene crack at the slightest ice pressure, while premium baskets made from thicker ABS plastic or UV-stabilized polypropylene can withstand minor frost without damage. If you live in an Ottawa neighbourhood where you routinely keep your pool open into early October, investing in a high-quality replacement basket for $25 to $40 rather than the cheapest $10 to $15 option provides some additional frost tolerance — though no basket can survive a hard freeze without water level management and a gizzmo.

Multiple skimmers require individual protection. Larger Ottawa pools — common in executive homes in Bridlewood, Riverside South, and Stonebridge — often have two or three skimmers. Each skimmer needs its own gizzmo, its own antifreeze treatment, and its own basket removal. At $8 to $15 per gizzmo and $15 to $25 worth of antifreeze per skimmer line, protecting a three-skimmer pool adds approximately $70 to $120 in materials compared to a single-skimmer pool. This cost is negligible compared to the $1,500 to $4,500 repair bill for multiple cracked skimmer bodies.

Spring follow-up is equally important. When you open your pool in May, inspect each skimmer body carefully before reinstalling the baskets. Look for hairline cracks along the bottom and side walls of the skimmer housing, particularly at the corners where stress concentrates. Shine a flashlight inside and check for any signs of water seeping through cracks from the soil side. A cracked skimmer body that is not leaking yet may survive another season with marine epoxy patching at $20 to $40 for materials, but this is a temporary fix — plan for a proper replacement before the following winter if you find damage.

Need help winterizing your pool before Ottawa's first frost? Ottawa Pool Installation connects homeowners with local pool closing professionals who protect every component of your pool system against freeze damage.