The end of summer is bittersweet for pool owners. While it’s nice to get a break from pool maintenance, you’ll need to properly winterize your pool first. Winterizing with the right chemicals is crucial to keep your pool in good shape until next season.
In this comprehensive guide, we’ll discuss which chemicals you need to close a pool for winter and how to use them. With the proper preparation, opening your pool next spring will be hassle-free.
Why Proper Winterization is Important
Before jumping into the chemicals, let’s discuss why you need to winterize your pool in the first place. When you leave a pool neglected over the winter, several problems can occur:
- Algae growth – Stagnant water provides the perfect environment for green, black, and mustard algae to thrive. This leaves you with a massive algae problem next spring.
- Staining and scaling – Without proper chemical levels, metals in the water can attach to pool surfaces and cause unsightly stains and mineral scale buildup.
- Equipment damage – From cracks in the pool shell to corrosion of ladders and filters, the cold winter elements can damage your pool equipment.
- Cloudy green water – Without a sufficient chemical regimen, your pool water will be a murky, green mess come spring.
Proper winterizing provides a protective chemical barrier against these issues. Below, we’ll go through exactly which chemicals you need and how to use them.
Supplies Needed for Pool Closing
Before we get to the chemicals, gather some supplies you’ll need for the pool closing process:
- Pool cover – Choose a winter cover designed for securing pools in cold weather. Look for one with good durability, ventilation, and drainage holes to keep water from accumulating on top.
- Pool cover pump – Also called a water bladder, this fits under the cover to pump off rainwater and melted ice so the cover doesn’t sag from the weight.
- Gloves – Wear waterproof gloves when handling pool chemicals to protect your hands.
- Testing kit – Use a test kit before closing to ensure proper water balance.
- Tile loosener – If you have a vinyl liner pool, use a tile loosener to detach the liner from pool walls before draining the water level.
- Submersible pump – Use this pump to drain water from the pool plumbing lines.
Now let’s get into the key pool closing chemicals you’ll need.
Chlorine-Free Shock
Chlorine-free shock, also called non-chlorine shock or potassium monopersulfate, is an essential part of winterizing your pool. It helps maintain clean water because the chlorine stops working as effectively in colder temperatures.
Here’s what you need to know about using shock:
What It Does
Chlorine-free shock oxidizes organic contaminants like bacteria and algae spores. It also neutralizes ammonia, chloramines, and other compounds that deplete chlorine levels. In short, it provides a clean baseline before closing down the pool for winter.
When to Shock Your Pool
Plan to shock your pool 2-3 days before adding the other closing chemicals. This gives the shock time to fully circulate and work through the water.
Closing Shock Dosage
Follow the dosage guidelines on the packaging based on your pool’s size. Spread the shock evenly across the length of the pool as you add it.
Use chlorine-free shock at double or triple strength for proper pool closing. Single doses may not provide enough cleansing power.
Using Shock After Closing
We recommend adding one last extra dose of shock directly on top of the winter cover once the pool is fully closed. This gives an added layer of protection against contaminants all winter long.
Now that you know how to use chlorine-free shock, let’s move on to other important chemicals.
Winter Algaecide
Green, black, and mustard algae can easily grow even in a covered pool if the water contains enough nutrients to feed on. That’s where winter algaecide comes in.
Winter algaecide provides long-lasting prevention against algae growth for up to 6 months. Here are tips for using it:
Look for Long-Lasting Formulas
When selecting a winter algaecide, check that it’s formulated to last for at least 3-6 months. This ensures it will remain effective throughout the winter.
Proper Dosage is Key
Carefully follow the label directions to calculate the proper dose for your size pool. Under-dosing could lead to gaps in protection, while overuse wastes money without added benefit.
Application Timing Matters
Add winter algaecide about 1 week before fully closing the pool. This allows it to circulate adequately through the water. It also gives a dose of protection before the chlorine from shocking dissipates.
For Best Results, Combine with Shock
Using winter algaecide in conjunction with chlorine-free shock provides a one-two punch. The shock first eliminates any existing algae, while the algaecide provides ongoing prevention once closed.
With both shock and algaecide, your pool will stay algae-free no matter how cold it gets.
Stain and Scale Prevention
In addition to algae, stained and scaled pool surfaces can be another unpleasant surprise after winter. Stain and scale treatments prevent this through sequestering agents that stop minerals from binding to pool walls, floors, and equipment.
Follow these tips for adding stain and scale prevention:
Metal Staining vs. Scaling
Staining refers to metals like copper and iron that discolor surfaces upon contact. Scaling occurs when calcium and other minerals bind to form white or gray deposits.
Add at Shocking Stage
Add your scaling and staining treatment when you shock the pool right before closing. This allows the sequestering agents to fully dissolve and get to work.
Monthly Dosing
If you use a monthly stain and scaling product during the season, one last large dose at closing should suffice. For single-dose products, match the amount to your pool’s size.
Combine With Algaecide
An algae barrier and anti-stain/scale product complement each other perfectly. The algaecide prevents biological growth while the anti-stain/scale treatment prevents mineral deposits.
With both chemicals, your pool surfaces will stay free of unsightly spots and residue.
Maintaining Proper Winter pH
Balancing your pool’s pH before closing is also important. Proper winter pH helps:
- Maximize the effectiveness of closing chemicals.
- Avoid etching or pitting of pool surfaces from chemical reactions.
- Reduce corrosion of metal components.
Here are tips for managing pH before closing:
Test Water 2-3 Days Beforehand
Ideally, maintain a pH between 7.2-7.6 prior to closing. Test a few days early so you have time for adjustments.
Lower pH if Needed
If the reading is above 7.6, lower it using muriatic acid or another pH decreaser, following product directions.
Raise pH if Needed
If pH reads lower than 7.2, you can increase it using soda ash or sodium bicarbonate per label instructions.
Recheck After Adding Chemicals
Test again after adding winter chemicals to make sure they did not affect pH. Make final adjustments as needed.
With ideal pH balance, the other chemicals will work more effectively and your pool surfaces will stay protected.
Using a Pool Cover Winter Floater
Finally, a winter pool floater provides sustained chlorine levels while the pool is closed. Simply fill the floater with chlorine tablets and place it in the center of your pool before covering.
Here’s how a winter floater works:
Slow-Release System
The floater has openings at the bottom to slowly release a small amount of chlorine at a time. This maintains adequate chlorine levels even in cold temperatures.
Visible Chlorine Supply
You can see the tablets inside the clear floater to know if you’re running low and need to replenish before spring.
Easy Center Placement
The floater conveniently rests in the middle of the pool as you cover it for the winter season. No need to try placing tablets across the bottom.
Floats as Water Level Drops
As the pool slowly loses water over the winter, the floater will descend to remain at the water line. This ensures tablets stay submerged.
Fresh Tablets Only
Make sure you fill the floater with fresh chlorine tablets rated for winter use. Old or summer-grade tablets likely won’t provide sufficient chlorine release.
With a fully loaded floater, your pool gets a steady chlorine supply all winter long.
Step-by-Step Guide for Closing Your Pool
Now that you know which chemicals to use, follow this step-by-step guide for safely closing your pool:
1. Test and Balance Water
Test for proper pH, alkalinity, and calcium hardness. Make adjustments as needed to get all levels ideal.
2. Brush and Clean Surfaces
Give surfaces a thorough brushing and vacuuming to remove any debris and algae. Clean the filter and skimmer baskets too.
3. Add Stain & Scale Prevention
With water circulating, add the recommended dose of stain and scale inhibitor per label instructions. Let it dissolve and circulate completely.
4. Shock the Pool
Shock the pool with chlorine-free shock at double or triple strength. Spread it evenly across the surface. Run the pump to circulate.
5. Add Winter Algaecide
Measure out the proper amount of algaecide based on pool size. Add it and let the pump run to distribute it evenly.
6. Install pool floater
Place the filled winter chlorine floater in the center of the pool.
7. Drain water level
Lower the water to below the skimmer mouth and return line. Use a submersible pump to drain all plumbing lines.
8. Detach vinyl liner
For vinyl liner pools, use a pool tile loosener to detach the liner from all surfaces to prevent damage.
9. Add extra shock
Add one final dose of shock directly onto the cover once the pool is closed. This gives a boost through winter.
10. Install cover
Place your winter pool cover over the entire pool and secure the edges. Install a cover pump in the middle to prevent water accumulation.
11. Clean filter & equipment
With the pool closed, drain and thoroughly clean the pump, filter, and other equipment and store safely away from freezing temperatures.
With this process complete, your pool is officially ready for winter hibernation! The chemicals you added will keep it protected until spring reopening.
FAQs about Pool Closing Chemicals
Here are answers to some common questions about closing chemicals:
How often should I check the pool during winter?
Check the covered pool every 2-3 weeks. Look for any sagging from water buildup and check that the floater doesn’t need fresh chlorine tablets.
What’s the ideal winter pH?
Ideally maintain a pH between 7.2-7.6 while the pool is closed. This allows your chemicals to work most effectively.
Can I just drain the pool instead of using chemicals?
Simply draining the pool removes the extra protection. Chemical winterizing provides algae prevention, water balancing, and surface protection that draining alone does not.
Are closing chemicals safe for vinyl liner pools?
Yes, as long as you follow dosage directions. Shock and algaecides are formulated to be liner-safe when used properly. Just avoid any products containing acid.
How do I reopen the pool after winter?
When spring arrives, open the cover and test the water’s chemical levels. Balance and shock the water, clean surfaces thoroughly, and restart your pool’s filtration to get it swimmable again.
Properly winterizing your pool requires a bit of effort, but saves much more work when opening it after cold weather. With this guide, you can winterize like a pro using the right chemicals and techniques. Contact us if you need any help getting your pool ready for its long winter’s rest.