The week before
Balance the water while the pump is still running. Corrections need circulation, and a pool dosed on closing day is a pool full of chemicals that never mixed, sitting still for five months. Get total alkalinity into band, pH into the WHO range of 7.2 to 7.8, and check calcium hardness against what the shell can tolerate.
Chlorine is the exception: bring it to the top of the working range on the day itself, not a week early, because it is going to decay all winter regardless.
Closing day: water and lines
Lower the water to the level your cover type and your climate call for — mesh safety covers, solid covers and no cover at all want different levels, and the manufacturer’s instruction beats any general rule you read anywhere, including here.
Then blow every line clear and plug it at the wall. Set a gizmo in the skimmer throat so ice has somewhere to go instead of into the concrete. This is the step that separates an uneventful spring from a plumbing invoice.
The equipment pad
| Component | Do | Why |
|---|---|---|
| Pump | Both drain plugs out, basket empty, plugs in the basket | A cup of water splits the volute |
| Filter | Clean it, drain it, valve to winterise | Media sits all winter either way |
| Heater | Both plugs out, gas off at the valve | Exchangers are the expensive failure |
| Salt cell | Acid wash if due, then store indoors | Freezing a wet cell cracks it |
| Power | Off at the breaker, not the timer | A timer can be switched on by anyone |
Photograph the pad before you take anything apart. Next spring, that photo answers every “which way was this valve?” in five seconds.
The cover
Clean the deck first so you are not dragging grit across the cover, then fit it tight enough that it does not develop a low spot. A slack cover collects rain, sags, and tips the whole lot into the pool during the first thaw. Put the cover pump where it can actually reach the low point, not where it is convenient to plug in.
Through the winter
Tell the client the two things that matter between now and spring: check the cover after storms, and run the cover pump before standing water freezes into a sheet. Everything else waits. A pool closed properly and checked twice comes back in three days rather than as a green-pool recovery.