How to Open Your Pool, Cover Off to First Swim

First, a reassurance: the water under the cover will probably look bad. Green, cloudy or full of leaves is normal for a pool that has sat closed since October. It tells you very little about how the season will go. What matters is the order you bring things back to life.

Opening usually happens in Toronto from late April through May, once the worst frosts are past. Our post on when to open your pool in Ontario covers timing. Opening earlier usually means less algae to clear, because cold water is easier to recover than warm water that has sat untreated.

Day one: cover off and equipment back

1. Clear the cover. Pump or sweep off standing water and leaves before you release anything, so they don’t end up in the pool.
2. Remove the cover, clean it, let it dry fully, and store it folded off the floor.
3. Take out the winter plugs and the skimmer guard. Replace them with the summer return fittings and skimmer basket.
4. Reinstall the drain plugs in the pump, filter and heater. If you followed our closing advice, they’re in the pump basket.
5. Reconnect anything you brought indoors, such as the salt cell, the chlorinator, or a portable pump.
6. Raise the water level to the middle of the skimmer opening.
7. Prime and start the pump, then check for leaks at every fitting as pressure builds. Note the clean filter pressure reading. You’ll compare against it all season.
8. Put the ladders, rails and steps back, and screw down the safety cover anchors so they sit flush with the deck.

Days one to three: getting the water back

Run the pump continuously for the first few days. Then:

• Skim, brush and vacuum out the debris. If there’s a lot of fine sediment, vacuum to waste so it bypasses the filter.
• Test and balance in order: alkalinity, then pH, then chlorine. Our pool chemicals guide explains why the order matters.
• Shock, usually at a heavier dose than a summer shock. A very green pool may need more than one.
• Clean or backwash the filter often while the water is clearing. It’s working much harder than normal.

A clear pool after opening typically takes anywhere from a day to about a week, depending on how it looked under the cover and how warm the weather is.

When can you swim?

When the water is clear enough to see the main drain, chlorine and pH are back in range, and a day has passed since the last shock. Swimming in water that is still cloudy isn’t just unappealing. It means the sanitizer is still fighting a load.

Things to watch for

• A pump that won’t prime, or a stream of bubbles in the pump basket, often points to an air leak on the suction side or damage from water that froze over winter.
• A heater that won’t light after sitting all winter needs a check before you rely on it. Gas heaters must be serviced by a licensed gas technician in Ontario.
• Water dropping overnight after you’ve filled it suggests a leak, possibly from a pipe that froze.
• Wrinkles or a liner pulling away from the wall need attention before the water warms up.

Questions we get asked

Should I shock the pool before or after removing the cover?

After. Get the cover off, clean out the debris, start circulation and balance the water first.

Do I need to replace the water?

Usually not. You top it up. Very high stabilizer or calcium from previous seasons is the main reason to partly drain, and only after testing.

Can you open my pool for me?

Yes. See our pool opening service in Toronto, or use the short pool opening checklist if you’re doing it yourself.