Pool winterizing kits are one of the most redundant products in the pool industry.
The truth is, most winter closing kits provide you with unnecessary and potentially even disruptive pool chemicals to make them appear more valuable than they really are.
Should anyone buy one of these kits? What’s the alternative when it comes to closing your pool? This article will lay it all out.
Quick answer: For the vast majority of pools, shocking and balancing the water is more than enough to ensure a smooth opening the following season, though a dash of algaecide to see it through the winter certainly doesn’t hurt.
What Do You Get in a Pool Closing Kit?
Let’s start by breaking down the usual products included in a winterizing kit:
- Shock or Oxidizer. All pool closing kits come with shock treatment or oxidizer to sanitize and break down any combined chlorine in the water.
- Algaecide. Most pool closing kits also often provide algaecide as an additional protective measure against algae blooms.
- Anti-stain. Many closing kits include anti-stain (metal sequestrant) to clump metals and minerals in the water, preventing them from staining your pool surfaces.
- Anti-scale. Some kits come with an anti-scale (scale inhibitor) to keep excess calcium in a dissolved state to prevent calcium scaling.
- Antifreeze. Many kits include antifreeze to stop the water in your skimmer and plumbing lines from freezing, expanding, and breaking your pipes.
- Enzymes. Some kits come with enzymes to help break down and oxidize organic and non-organics in the water, reducing the load on your chlorine throughout the winter.
- Accessories. Some winterizing kits bundle in accessories like floaters, sponges, or sometimes even covers to sweeten the deal.
Why Most of Those Things Are Unnecessary
As good as those products sound, most of them are subpar or simply not needed when closing your pool.
Let’s tackle each one in more detail.
Most Closing Kits Give You a Weak Shock
Most winterizing kits contain non-chlorine shock because it’s generally safer to use and less harsh on vinyl and fiberglass pools.
Since manufacturers don’t know what type of pool you have, they almost always opt to include a “catch-all” shock treatment (non-chlorine shock) even though it’s less effective than chlorine shock.
In truth, you can use chlorine shock in any type of pool as long as it’s properly handled and diluted before adding it to your water — and you really should be using the best possible treatment if you’re closing down for the winter.
What’s more, if you already use chlorine shock as part of your maintenance routine, you probably already have this chemical on hand without having to rely on a kit to provide it.
Algaecide Is Optional for Chlorine Pools
A lot of pool owners like to dump algaecide into their swimming pool before covering up for the winter.
While this isn’t necessarily a bad idea, it’s not always required if you have a chlorine pool because chlorine is far more effective than algaecide at preventing algae growth.
Algaecide simply adds a fallback layer of protection against algae — and one that typically only comes into play if you fail to follow the proper closing procedure for a pool.
With that being said, algaecide plays a more important role in a non-chlorine pool because other sanitizers typically aren’t as capable of defending against algae, at least not for a sustained period.
But even if you do choose to use algaecide, closing kits don’t always give you the most optimal type of algaecide.
Some kits include a metallic algaecide along with anti-stain to counteract the additional copper being introduced to the water, but this is a cost-cutting measure and it adds more risk to you with no practical upside.
For closing a pool, 60% polymer algaecide (or polyquat 60) is widely considered to be the best. It works against most types of pool algae and won’t cause metal staining because it doesn’t introduce more copper into your water.
You Probably Don’t Need Anti-Stain
High metal content in your water can cause metal staining on your pool surfaces.
By using anti-stain, otherwise called metal sequestrant, you can clump the metal particles together to prevent them from depositing on your pool.
In this case, you only need to worry about metal staining if your pool has a high metal content upon closing, or if you’re using a metallic algaecide that will ultimately add copper to your water.
If you’re under those levels, you’re not at risk of metal surface stains and there’s no benefit to using stain-prevention products in your pool.
If you do happen to be using a copper-based algaecide, you will need to pair it with metal sequestrant to counteract the increase in metal — which, as mentioned, is why you often see both products bundled into a pool closing kit.
With that being said, we still don’t recommend this pairing because the more effective the sequestrant, the less effective the algaecide becomes. It’s a fight you’re never truly going to win.
Note: You’ll want to stay below 0.3 parts per million (ppm) for iron and copper, and below 0.1 ppm for manganese.
You Probably Don’t Need Anti-Scale
Just like with metals, high calcium content in your water can lead to calcium stains forming on your pool surfaces.
Anti-scale, sometimes called scale inhibitor, keeps excess calcium dissolved in your water when it otherwise would crystalize and precipitate out, causing cloudy water and eventually calcium scaling.
Again, this only applies if your calcium hardness level is too high — which is something you should correct before closing your pool anyway.
Saltwater pools are a little more sensitive to scale formation due to their higher resting pH level, so you’ll want to stay below 400 ppm.
Overall, rebalancing is always better than trying to manage an imbalanced pool. If there was ever a band-aid solution to a pool chemistry problem, using a scale inhibitor is undoubtedly it.
Note: The threshold is very forgiving for traditional chlorine pools. Most plaster, fiberglass, and vinyl pools can tolerate a calcium hardness level of up to 500-600 parts per million (ppm) before scale becomes an issue.
You Probably Don’t Need Antifreeze
When you close a pool, one of the most crucial steps is blowing out and plugging the plumbing lines to prevent the pipes from freezing up.
If done correctly, there should be no water in the lines, which means they can’t freeze over.
In that case, the only reason you would want to use antifreeze is if you’re not confident in your ability to blow out the lines, making it more of an insurance policy to hedge against human error than anything else.
If using antifreeze in your pool helps you sleep at night, by all means, go ahead and use antifreeze when closing your swimming pool.
In fact, if you’re concerned enough to use antifreeze, you should probably get a gizmo to protect your skimmers from cracking under the expansion of ice.
For most pool owners, though, these things simply aren’t necessary.
You Absolutely Don’t Need Enzymes
Some pool owners use enzymes to help break down and oxidize organic and non-organics in the water, effectively reducing the load on your chlorine.
It sounds good in theory, right?
The problem is, that it’s far more expensive to use enzymes alongside chlorine when you can just use more chlorine.
Where a better case can be made in smaller bodies of water (like hot tubs), it simply doesn’t make sense for a swimming pool.
In the end, much like phosphate or nitrate removers, enzyme products are largely an unnecessary expense when it comes to pool maintenance.
You Don’t Need Random Accessories
Some closing kits will try to win you over with bonus pool equipment like chlorine floaters and absorbent foam sponges. Some even come packaged in fancy boxes or carrying cases to really make a statement.
Of course, none of this makes any difference when it comes to winterizing your pool the right way, and it certainly won’t be the deciding factor in opening a clean and clear pool.
While these little freebies can make you feel like you’re getting a good deal, they’re just gimmicks that offer very little to the pool closing process.
What You Should Buy Instead
If closing kits are a waste of money, what should you buy instead?
Well, for almost everyone reading this, the answer is lots of chlorine and possibly a dash of algaecide for peace of mind.
Seriously, that’s it.
For the minority of pool owners using alternative sanitizers like bromine or biguanide, simply swap out the chlorine for your chosen sanitizer, and be sure to use plenty of algaecide.
Overall, shocking and balancing the water is 90% of the work when it comes to keeping your pool water clean and clear throughout the winter months.
The rest depends on the temperature of the water, how much water you drained from your pool, and how effectively you blew out the lines to prevent freezing.
The Bottom Line
Pool closing kits sell you on the convenience of having “everything you need to close a pool”.
In reality, they inconveniently provide subpar and unnecessary chemicals.
The best approach is always to identify the few chemicals and accessories you really need for closing your pool, and individually buy the most suitable variant of those products.
For many, it’s as easy as buying more chlorine and algaecide.