Why Winterizing Matters
If you live where it freezes, closing your pool correctly is the single most important maintenance task of the year. Skip a step and you risk cracked plumbing, a damaged pump, or a green swamp to clean up in spring. Done right, winterizing protects your equipment and makes opening a breeze.
Here's the step-by-step.
Step 1: Balance the Water (A Few Days Before)
Balanced water protects surfaces and equipment all winter. Target:
- pH: 7.2-7.6
- Alkalinity: 80-120 ppm
- Calcium hardness: 200-400 ppm
- Chlorine: shock to a high level, then let it come down before covering
Balancing a few days ahead lets shock levels normalize.
Step 2: Deep Clean
Skim, brush, and vacuum thoroughly. Any debris left in the pool over winter stains surfaces and feeds algae. A clean pool closes better and opens cleaner.
Step 3: Lower the Water Level (Freeze Climates)
For pools with skimmers, drop the water below the skimmer mouth (or to the manufacturer's recommended level). This prevents water from freezing and expanding in the skimmer and plumbing.
*Note: with some cover systems you keep the level higher — follow your cover's instructions.*
Step 4: Blow Out and Plug the Lines
This is the step that prevents the most expensive damage. Water left in plumbing can freeze, expand, and crack pipes underground.
- Use a shop vac or air compressor to blow water out of each line
- Plug the lines with winterizing plugs as you go
- Add pool antifreeze to lines where recommended (never put automotive antifreeze in a pool)
If you're not confident here, this is the step to hire a pro for — a cracked underground line is a major repair.
Step 5: Winterize the Equipment
- Drain the pump, filter, heater, and chlorinator
- Remove drain plugs and store them in the pump basket so you can find them in spring
- Bring removable equipment (pump, cartridge filters) indoors if possible
- For sand/DE filters, set the valve to "winterize" or follow the manufacturer's guidance
Step 6: Add Winterizing Chemicals
A winterizing kit typically includes:
- Winter algaecide
- A final shock or oxidizer
- Sometimes a stain/scale preventer
Add these last, after the pool is clean and balanced.
Step 7: Cover It
- Safety cover: best protection, keeps kids/pets/debris out
- Solid winter cover: blocks light (prevents algae) but needs a cover pump for rain/snow melt
- Mesh cover: lets water through, easier to manage
Use an air pillow under solid covers in hard-freeze climates — it absorbs ice expansion and protects the walls (critical for above-ground pools).
Above-Ground vs In-Ground Notes
Above-ground: the air pillow is essential — ice expansion can buckle the walls. Don't fully drain (an empty above-ground pool can collapse or shift). In-ground: plumbing blowout and proper water level are the priorities. Gunite/plaster and vinyl surfaces have slightly different ideal levels — check yours.Winter Check-Ins
- Pump standing water off solid covers after rain/snow
- Check the cover for tears or sagging
- Watch for ice damage to coping or the cover
Bottom Line
Winterizing is mostly about one thing: keeping water out of places where it can freeze and crack something expensive. Balance, clean, blow out the lines, protect the equipment, and cover it well. If the plumbing blowout makes you nervous, hire a pro — it's the cheapest insurance against the costliest mistake.
Find a pool service company near you that handles seasonal closings and winterization in your area.