Summer can feel like it ended overnight. The towels are packed away, sunscreen is sitting unused, and you’re checking the weather more often. That first cold breeze isn’t just a sign to grab a warmer jacket it’s your reminder that winter is coming. Before Ottawa freezes over, it’s time to think about your fiberglass pool.
A fiberglass pool is low maintenance during summer, but winter is different. Simply throwing a cover over it and hoping for the best can lead to problems come spring cracked pipes, dirty water, and expensive repairs. Closing a pool properly isn’t just about shutting it down. It’s about protecting it from freezing temperatures, ice, and pressure damage.
Taking the right steps now means you can enjoy Ottawa’s winter festivals without worrying about what’s happening in your backyard. No second-guessing while sipping hot chocolate or wondering if your pool equipment has frozen solid. With the right preparation, your pool will come through winter safely and be ready to enjoy again when warmer days return.
The reason why this is not a Maybe Later Job
Winterising may not sound exciting, but it’s important to understand why it matters. Water doesn’t just freeze it expands. When it does, it pushes with force and looks for the weakest points in your pool system to break through.
This is what you will lose in case you cut corners:
Plumbing Nightmare:
That water in the pipes to your pump and filter? It will freeze. And ice growing does not meekly request additional space it pushes through PVC or breaks metal pump housings. It is the most widespread and sickly expensive winter error.
The Pool Shell
Fiberglass pools are strong, but they’re not indestructible. Ice forming on the water can press against the pool walls. At the same time, groundwater around the pool can freeze and expand, pushing from the outside. Without proper winterising, this pressure can damage the pool shell. Correct preparation helps balance these forces and protect the pool.
Poor or Loose Pool Covers
A cheap or badly fitted cover can cause problems. Snow and ice can weigh it down until it sags into the pool. In some cases, the cover can collapse completely, leaving dirty water and debris inside. By spring, this turns into a smelly mess that’s difficult and time-consuming to clean.
Stains on the Pool Surface
Closing a pool while it’s dirty can lead to lasting stains. Dirt, algae, and minerals can sit on the surface all winter and dry onto the fiberglass finish. This often leaves marks and discolouration that are hard to remove when the pool is reopened.
The good news? All of this is 100% preventable. It’s about a bit of know-how and a weekend of work. And the perfect deadline to aim for? Getting it done well before the city comes alive for the Winterlude Weekend in Ottawa. Trust me, you don’t want to be wrestling with a cover while everyone else is heading to the Canal.
Your Straight Talk, Step-by-Step Guide
Plan for a dry, halfway decent Saturday in late fall. You want the water cold (below 15°C so algae is sleeping) but the air temperate enough that you’re not wearing three pairs of gloves.
Step 1: Give It a Proper Send-Off (The Clean)
Don’t just shock it and walk away. Show it some respect.
- Test and Tweak the Water: Use your test strips or kit. Get the pH, Alkalinity, and Calcium Hardness into the recommended range. This isn't just for now it keeps the water from getting corrosive or scaly over the long months ahead.
- The Final Shock: About a day before you shut it down, give the pool a strong dose of chlorine shock. Walk around the edge as you pour it in. This is the "scorched earth" policy for any last-minute algae trying to set up shop.
- The Big Scrub: This is your workout. Brush every single surface walls, floor, the corners, the steps. Get all the invisible film off. Then, vacuum it all up. For this final clean, vacuum to "WASTE." This sends the dirty water out of the pool instead of through your filter. Yes, you'll lose water. You were going to lower it anyway.
- Filter Spa Day: Now, clean your filter. If it's a sand filter, give it a long backwash. If it's a cartridge, pull it out and hose it down until the pleats are white again. Let it dry completely in the sun.
Step 2: The Water Level Question
This is where people panic. How much water do I drain? For a fiberglass pool, the rule is simple: Never drain it completely. The water left inside is a crucial weight that counteracts groundwater pressure from below.
Lower the water to about 4-6 inches below the bottom of the skimmer opening. That’s it. This protects the skimmer from ice damage but leaves plenty of water as an anchor. Use a submersible pump or your pool’s waste setting to do this.
Step 3: The "Make or Break" Step: Emptying the Pipes
This is the heart of winterizing. You must get the standing water out of all the plumbing. A shop-vac with a blower function works, but a dedicated pool air blower is better.
- Kill the Power: Go to your circuit breaker and turn off the power to the entire pool system. No exceptions.
- Drain the Equipment: Find the little plastic drain plugs on the bottom of your pump, filter, and heater. Unscrew them and let everything dribble out. Put these plugs in your pump basket. You will forget where they are by spring.
- Blow Out the Lines: Connect your blower to the skimmer line. Start with the main drain. Blow air until you see a huge, steady stream of bubbles coming from the drain on the pool floor. That means the pipe is clear. Then, switch to each return jet line (the ones that push water back in), blowing air until water stops spraying out of the jet.
- Plug It Immediately: The second you stop blowing on a line, plug it shut. For return jets, use black rubber expanding plugs. Twist them tight.
- Protect the Skimmer: Screw a skimmer guard (often called a Gizzmo) into the skimmer opening. It’s made to take the pressure if ice forms. After that, pour a bottle of pink, non-toxic pool or RV antifreeze into the skimmer.
- Use Antifreeze as Backup: Once each pipe has been blown out, add a small amount of pink antifreeze into the lines. This helps protect against any water left behind.
Step 4: Cover and Protect the Pool
You’re nearly finished.
- Ice Pillow: Inflate an air pillow and place it in the centre of the pool. Tie it in place. If ice expands, it presses on the pillow instead of the pool walls.
- Winter Chemicals: Add a pool-closing chemical kit or slow-dissolving chlorine tablets and algaecide. Follow the instructions for your pool size.
- Put the Cover On: Secure the pool cover tightly. A tight cover helps snow slide off and stops it from sagging into the water. Loose covers cause problems.
Step 5: Store Summer Equipment
Clean and store items like the filter cartridge, ladder, solar cover, and pool floats in a garage or shed. To keep rodents out, place a piece of cloth or insulation into open pipes or the skimmer opening.
The Winter Watch: Quick and Easy Check-Ins
Once it’s closed, you’re not done forever. You simply put it in monitor mode.
After USA Snowfalls: We fall on. When a big storm has come, the kind of snow that is a Winterlude Weekend special in Ottawa, loose a little of the snow on the centre of the cover with a long-handled soft brush. Never walk on the cover, and be no hero and attempt to have it all. You are merely averting the accumulation of the weight of crush.
Pillow Check: Air pillows at times leak. Look under the cover stitching here in a mid-winter. In case it is deflated, take it out and inflate.
Cover Patrol: Check on after a raging windstorm, to see that all straps, springs or water bags are in place.
The Expensive "Oops" Things to Do Away With
Learn not to make the mistake others make:
Pumping out the Pool Dry: This is one of the biggest mistakes with fiberglass pools. Never drain the pool dry. Without water, the shell can shift, crack, or lift due to ground pressure.
Application of the Car Antifreeze: The pink pool/RV antifreeze is not toxic. The green automotive stuff is toxic and will destroy your pool.
Fraud: Antifreeze: It is a back-up, not a primary policy. To blow the lines out is 90 per cent of the work.
Closing Too Late: When you shut the stable door when it is frozen, you have left it. It has to be an autumn thing, not a scramble at the last moment.
The Sweet Spring Payoff
The payoff comes in spring. When the ice melts and warmer days return, your pool will be easy to open, clean, and ready to use. No major repairs, no surprises, no delays.
Closing your pool properly lets you enjoy Ottawa’s winter without worry, knowing everything is protected. When summer comes back, your pool will be waiting , just as it should be.
FrequentlyAsked Questions
Because water freezes and expands. If there’s still water in your pipes, pump, or filter, it will freeze, crack things, and you’ll be looking at expensive repairs come spring. A cover alone doesn’t stop ice damage. You’ve got to get the water out of the plumbing, lower the pool water correctly, and protect the equipment. It’s a few hours of work that saves you thousands later
Not too much and never drain it completely. Lower it to about 4 to 6 inches below the bottom of the skimmer opening. That’s it. The water left inside helps weigh the pool down so groundwater pressure doesn’t push the shell up or crack it. Draining a fiberglass pool dry is one of the biggest mistakes people make.
Blowing out the lines is the main job. Antifreeze is just backup. If you don’t blow the water out first, antifreeze gets diluted and can still freeze. You use a blower or a strong shop vac to push air through the pipes until water stops coming out of the returns and main drain. Then you plug the lines and add a bit of pink antifreeze for safety. Skip this step and you’re gambling on cracked pipes.
Only use pink RV or pool antifreeze. The green stuff you put in your car is toxic and will ruin your pool and void warranties. Pink is non‑toxic and safe for pool plumbing. You’ll find it at any pool supply shop. Pour it into the skimmer and return lines after you’ve blown them out.
A couple quick checks. After a big snowfall, gently brush snow off the cover; don’t walk on it. Check that the cover straps or water bags are still tight after wind storms. And every now and then, peek under the cover to see if the ice pillow is still inflated. That’s it. A few minutes here and there keeps things from turning into a spring disaster.
