Pool opening: getting the spring startup right
Reopening your pool at the right time saves a lot of trouble. Too late, and the water has already turned green; at the right time, the startup is simple. The benchmark: water rising back above 12 °C.
In short
You reopen when the water durably exceeds 12 °C: beyond that, algae start again, so it is best to take control before they do. The startup is not about draining, but about putting filtration back in service, cleaning, rebalancing the water and disinfecting. Done early and in the right order, it guarantees clear water without repeated shock treatments.
The right moment
The trigger is temperature, not the calendar: as soon as the water crosses 12 °C in spring, algae start developing again. Reopening then lets you disinfect still-healthy water, rather than having to rescue already-green water — far longer and costlier.
Don’t drain, rebalance
Except in special cases, you keep the winter water: systematic draining is pointless and risky for the pool. Remove the cover, put filtration back in service, clean the walls and floor, then rebalance (pH, alkalinity) and disinfect. A full analysis at the end of the startup validates everything.
What to do, step by step
Reopen when the water exceeds 12 °C
Watch the temperature rather than the date: it is what drives algae restarting.
Remove the cover and clean
Take off the winterizing accessories, clean the water line, floor and walls.
Put filtration back in service
Raise the water level, restart the pump and run filtration continuously at first.
Rebalance and disinfect
Adjust the pH and alkalinity, run a shock treatment, then check the full water balance.
Frequently asked questions
When should I reopen my pool?
As soon as the water durably exceeds 12 °C in spring. Waiting longer gives algae time to settle in.
Should I change the water at reopening?
No, you usually keep the winter water. A well-run startup (cleaning, balance, disinfection) is enough to get clear water back.
My water is already green, what do I do?
Follow the green-water rescue method: set the pH, shock-chlorinate, brush and filter continuously. It is longer, which is why reopening early is worth it.