The Ultimate Pool Closing Checklist for Minnesota

October 1, 2026  |  Your Happy Dolphin Pool & Spa Team

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Closing a pool right the first time saves you a hard spring. Miss a step now, and you might find a cracked pipe, a stained liner, or green water waiting for you in April. This checklist walks through the full job, start to finish. We'll dig deeper into each piece over the next few weeks, but here is the whole picture in one place.

1 Time It Right

Water temperature drives the calendar, not the date on your phone. Close too early and algae grows in warm, chemical-light water all winter. Close too late and you risk a hard freeze catching you off guard. We covered the exact temperature and timing signals to watch for in a separate article.

2 Give It One Last Deep Clean

Brush the walls and floor, vacuum any settled debris, and skim the surface clean. Anything left behind now sits under your cover all winter and feeds stains and algae. A clean pool at closing is a clean pool at opening.

3 Balance the Water Before You Cover It

Get pH, alkalinity, and calcium hardness into range before you close up. Unbalanced water sits and works on your liner, plaster, and metal fittings for months with nobody watching. BioGuard Balance Pak 100 raises alkalinity, Balance Pak 200 raises pH, Balance Pak 300 raises calcium hardness, and Lo 'N Slo brings pH and alkalinity down if you're running high. Stop in for a $7 water test — it's free with a $50 or more chemical purchase — and we'll tell you exactly what your water needs.

4 Shock and Protect Against Winter Algae

Shock the pool a day or two before you close it, then finish with a winterizing dose of algaecide. BioGuard Algae Complete is our lead recommendation here — it prevents and treats algae growth through the closed months. If you're working with a tighter budget, Back Up is a lower-cost preventative option, though it won't do as much on its own. Want it in one box instead of separate bottles? The BioGuard Arctic Blue Winter Kit pairs a cold-weather shock with an algae protector built for the closed season.

5 Lower the Water and Winterize the Equipment

Drop the water level below the skimmer and returns so freezing water has nowhere to crack a fitting. Then move to the pump, filter, and heater: drain them, blow out what water you can, and add antifreeze rated for pools where your closing kit calls for it. If your filter media is due for a change, this is a good time to do it — and any time we replace filter media, we replace the laterals underneath it too.

6 Blow Out the Lines

Push the remaining water out of every pipe running to and from the pool. Any water left in a line can freeze, expand, and split the pipe. This is one of those jobs you can do yourself with the right compressor, or hand to us if you'd rather not risk it.

7 Store Chemicals and Your Robot Cleaner Safely

Chemicals need a cool, dry, ventilated spot, kept apart from each other and away from anything that can pull moisture out of the air. Your robot cleaner needs its own care too — rinsed, dried, cord checked, and stored somewhere it won't freeze. We'll cover both in full detail later this month.

8 Choose Your Cover and Close It Up

Before the cover goes on, run a bottle of BioGuard Pool Closing Complete through the water. It's built to go in last — it clarifies the water, strips out phosphates, and protects surfaces and equipment while the pool sits closed. Then it's time for the cover. Mesh, bag, or no cover at all — each one changes how much work waits for you in spring. Stretch it tight, secure every anchor point, and check it after the first snow. We'll walk through picking the right cover for your pool later in this series.

What's Ahead in This Series

Closing Day Essentials

Not sure you want to tackle all eight steps yourself? Our closing service handles the whole checklist — because we make pool ownership a joy!

Call Us Now — 763-542-9000

Your Happy Dolphin Pool & Spa Team