Opening your pool in spring: step-by-step guide

Open your pool correctly in spring: remove the cover, clean the filter, treat the water and balance the chemistry. Plan 1 to 2 weekends for the opening process.

Opening your pool takes an average of 4 to 8 hours spread across 1 to 2 weekends. Do not rush it: the water treatment takes time. Start early enough to be swimming in a perfect pool by early May.

Step 1: Remove and clean the cover

Remove standing water from the cover with a submersible pump or wet vacuum before opening it, so dirt does not fall into the pool. Clean the cover with cover cleaner, rinse, allow to dry, and store in a cool, dry place.

Step 2: Inspect filter and equipment

Check the sand filter for clumping. Inspect all hoses and fittings for cracks or loose connections — frost can crack pipes. Perform a thorough first backwash of at least 5 minutes.

Step 3: Start the pump

Start the pump carefully for the first time after winter. Let it run 30 seconds, then stop and check all connections for leaks. Bleed air via the filter bleed valve.

Step 4: Top up the water level

Fill to halfway up the skimmer opening. After filling, retest the water — the fill water chemistry differs from the pool water.

Step 5: Test and balance the water

ParameterTarget
pH7.2 to 7.6
Free chlorine1.0 to 3.0 mg/l
Alkalinity80 to 120 mg/l
Calcium hardness200 to 400 mg/l

Correction order: alkalinity first, then pH, then shock treatment.

Step 6: Shock treatment

A shock treatment is always needed when opening. Add liquid chlorine or calcium hypochlorite in the evening to reach 10 mg/l free chlorine. Run the pump overnight and the following day. Backwash the filter the next morning.

After 24 hours add preventive algicide for extra protection in the first weeks of the season.

The pool is ready to swim when

  • pH is between 7.2 and 7.6
  • Free chlorine is between 1.0 and 3.0 mg/l
  • The water is clear and blue

Recommended products

Chlorine Tablets 200g (5 kg)

Chlorine Tablets 200g (5 kg)

4.6/5

Slow-dissolving chlorine tablets for use in skimmer or floating dispenser. 5 kg for a full season.

Our pick: Best value for routine chlorination

Price indication: EUR 34.99

This page contains affiliate links. If you purchase through these links, we receive a small commission at no extra cost to you.

Pool Test Strips 6-in-1 (100 strips)

Pool Test Strips 6-in-1 (100 strips)

4.5/5

Test pH, chlorine, alkalinity, hardness and more in one go. 100 strips per pack.

Our pick: Best choice for beginners

Price indication: EUR 12.99

This page contains affiliate links. If you purchase through these links, we receive a small commission at no extra cost to you.

Frequently asked questions

Open the pool when outdoor temperatures consistently exceed 15°C, typically late April to early May in Northern Europe. Do not wait too long: algae growth starts even at lower temperatures.

Yes, in most cases. Unless the water is severely contaminated (black, muddy), it is cheaper to treat it than to replace it. Follow the water treatment step-by-step plan.

With correct treatment, the water clears within 24 to 72 hours. Severely contaminated water can take 3 to 7 days. Backwash the filter daily.

Keep your pool clear with the right maintenance schedule

See our complete maintenance schedule with daily, weekly, and seasonal tasks.

View schedule

By

Zwembadwijzer

The Zwembadwijzer editorial team consists of experienced pool owners and water treatment specialists who combine practical knowledge for residential pool owners.