Uncover, top off, and reconnect
Start by clearing debris and water off the cover before you pull it, so the gunk does not fall into the pool. Remove the cover, clean and store it, and top the water back up to its normal level, which usually dropped over winter. Reinstall and reconnect the equipment you took out for the season: pump, filter, returns, ladders, and any plugs.
Get the pump and filter running before you start dosing chemicals. Circulation is what makes everything else work.
Clean before you treat
Skim the surface, brush the walls and floor, and vacuum out the debris that settled over winter. The cleaner the pool is before you balance the water, the less chlorine and effort it takes to clear. Empty the skimmer and pump baskets and check the filter is clean.
If the water is already green, do not panic; it is normal after a winter and the chemistry steps below handle it.
Balance in the right order
Test the water, then balance from the buffers up. Set total alkalinity first with the alkalinity calculator, because it steadies pH. Then adjust pH to 7.4 to 7.6 with the pH calculator. Check cyanuric acid and bring it into range with the cyanuric acid calculator, since it sets your chlorine target.
If you are not sure of your pool volume after topping off, the pool volume calculator gives you the gallons every dose depends on.
Shock and clear
With the water balanced, shock the pool to bring free chlorine up to the shock level for your CYA, which the shock calculator sets. Hold it there with the pump running until the water is clear, which can take from a day for a clean pool to several days if it opened green.
Once it is clear and holding chlorine overnight, let chlorine settle to your normal target and you are open. Clean the filter again after a heavy opening, since it catches a lot.
Do not skip the order
The single biggest opening mistake is dumping shock into unbalanced, dirty water and hoping. Clean first, balance the buffers, then chlorinate. Done in that order, opening is a short job. Done backwards, it is weeks of cloudy water.
Frequently asked questions
How do I open my pool for the season?
Clear and remove the cover, top off the water, and reconnect the pump and filter. Clean the pool by skimming, brushing, and vacuuming. Then balance the water in order: alkalinity, pH, then cyanuric acid. Finally shock to the level for your CYA and run the filter until the water is clear.
What chemicals do I add first when opening a pool?
Balance the buffers before chlorinating. Set total alkalinity first because it steadies pH, then adjust pH, then bring cyanuric acid into range since it sets your chlorine target. Only after that do you shock the pool. Adding shock to unbalanced water is the most common opening mistake.
Why is my pool green when I open it?
Algae grows over winter when chlorine is gone, so a green pool at opening is normal. After cleaning and balancing the water, shock it to the level for your cyanuric acid and hold that level with the pump running until it clears. A badly green pool can take several days.
How long does it take to open a pool?
For a pool that wintered clean, often a day or two to balance, shock, and clear. A pool that opened green takes longer, sometimes a week, because you have to hold shock level until the algae is gone. Cleaning thoroughly before you treat speeds the whole thing up.
When should I open my pool?
Open it once daytime temperatures are consistently warm, often when they reach the 70s Fahrenheit, even if you are not swimming yet. Opening earlier rather than later is easier, because warm water left covered and untreated grows algae fast, making the opening harder the longer you wait.