Best Pool Shock

We all love owning a swimming pool, right? Sometimes, especially in summer, it’s the best – or only – way of keeping cool at home.

But pools need maintenance, and whether you do it yourself, or hire someone to do it for you, you’re going to need to regularly shock your pool.

By giving it an intense dose of chlorine (up to 5 times the normal amount) every couple of weeks (plus in the event of specific, pool-contaminating events) you kill any growing bacteria, while clarifying your pool water.

All of that is great, but which are the best pool shocks to buy – and come to that, why? Isn’t one pool shock pretty much like another?

No, not really. Picking poorly here will leave you with mediocre results and a pool that’s less clean and clear that you’d like.

Don’t panic, though. We’ve found the best pool shocks on the market today, so you don’t have to compare them.

In a hurry? Here’s our top pick.


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The SpaGuard Enhanced Spa Shock 6# makes it to the top of our list of the best pool shock treatments because it does a lot of hard work from a single, simple treatment.

Taking only 1 pound of shock to clean up 10,000 gallons of pool water, and coming in a 6 pound bottle, there’s an economy to the SpaGuard Enhanced that belies its four-process cleaning action.

Relatively few pool shocks on the market claim to be dedicated shock-only treatments, but the SpaGuard Enhanced makes the most of its chemistry to deliver a clarifier, a chock, a pH buffer, and a flocculent.

That means it will do more than just deal with the algae and bacteria that will have been building in your pool since the last time you shocked it.

It will also break down all the human-goo that has leached into the water while you’ve been using your pool for the last two weeks.


All the stuff that comes out of us, like sweat and (this being a swimming pool, and humans being humans) any other bodily fluids that have been diluted in the water.

But beyond that, also all the sun lotions, moisturizing skin milks, any home tanning cream, as well as the standard soaps and shampoos that make us apes worth hanging with, will have left traces in the water.

The SpaGuard Enhanced Shock will help neutralize their effects and their presence.

The clarifier does exactly what it claims to do, letting you see clearly through the water again, rather than through that slightly murky soup you may not have noticed building up in your pool.

So, you get the four actions that clear the water, clean away the chemicals we add to our bodies, and kill the algae and bacteria in your pool.

As an extra bonus, you should be able to run this shock through the pool in around a quarter-hour, too, so you get started on that waiting period before you can get back in the pool fast.

The SpaGuard Enhanced Shock is a solution that plays well with a wide variety of pools, too – whether you have a chlorinated or a brominated system, you’re good with the SpaGuard.

Likewise, it will work just as well with ionization and ozone systems.

Secret ingredient?

Not so secret – the SpaGuard Enhanced Shock wins extra points for the simplicity and transparency of its ingredient-list, which is not necessarily a given with some other spa shocks.

But the active ingredient here is sodium dichlor at a 58% concentration. Just to be extra clear, you’re not going to want to get back in the pool for at least 25 hours.

Usually, when your shock contains sodium dichlor, it’s stabilized, so you can use it in the daylight without the UV rays from the sun affecting it.

But the SpaGuard Enhanced Shock is a non-stabilized sodium dichlor chlorine-rich shock, so it can bring you the benefits of a rapid effective shock without having to build in UV protection, which would be chemically complex and cost you more money – though you will have to use it when the sun goes down.

For your swimming pool and home spa, the SpaGuard Enhanced Shock is enough to put our mind at rest.


  • The four-action shock improves the clarity of the water
  • It’s particularly useful as a flocculant to capture and dispose of the oils and creams we spread on our bodies
  • It takes away the “Pool Odor” that can build up when a pool needs shocking


  • The non-stabilized nature of the shock means it’s less effective by daylight


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You’ve heard of Clorox. Chances are high that your family has been using Clorox products inside the house for generations to keep your surfaces clean and germ-free.

There’s no reason to think Clorox pool shock would be any different or less effective.

It’s another multi-functional high performance shock – clear water, and death to three kinds of algae – green, black and mustard algae (particularly prevalent in pools). Bacteria? Not a chance.

Like the SpaGuard Enhanced Shock, you’re talking about a 58% concentration of sodium dichlor.

And it’s equally rapid in its dispersion through the system – 15 minutes and your shock will be shocking nicely.

Again like the SpaGuard, the cleverest thing about the Clorox shock is that for all its chemical warfare on bacteria and algae, it doesn’t mess up your pool’s pH balance.

There’s little to choose between the SpaGuard and the Clorox, really – so how come the Clorox can only take second place? Honestly, it’s a writing gig. SpaGuard’s instructions are clear, simple, to the point – bang, you’re done and on with your day.

The Clorox instructions… to put it kindly, don’t let you get on with your day. It’s not quite at the same level of difficulty as folding a fitted sheet, but it’s up there.

By the time you’ve understood the instructions on the Clorox, the Spa Guard’s happily circulating.

So – second place for the Clorox Shock – but it’s still better than most other pool shocks out there.


  • The Clorox Shock kills three kinds of algae – including mustard algae
  • It’s another multifunctional shock that gets lots of jobs done – fast
  • It doesn’t affect the pH levels of your pool


  • The instructions are written by the Riddler


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Let’s talk about value for money for a moment. If you have a bigger pool, you’re going to need more than 1 pound of shock per instance of shocking.

Your sweet little Clorox 6-pack is going to be done in around 6 weeks.

By buying in bigger bulk, you take a slight hit now, but you have shock on hand for much longer, and for many more shocking sessions. Let’s talk about the DryTec Calcium Hypochlorite 24-pack.

Yes, it has the same power per pound as the earlier shocks – 1 pound equates to 10,000 gallons of shocked pool water. But you bulk order and then stop having to restock the shock.

The chemistry is different in this shock, too. Not sodium dichlor, but a 68% concentration of calcium hypochlorite, which make the DryTec a real, hardore player in the pool shock market.

Yes, it’s still an unstabilized shock, which means applying it at night, and the different chemistry means you might notice some initial sediment on the surface of the water with this one.

Disperse it with a brush and you’ll be fine. Think Kool-Aid, but for pools.


Leave it to do its thing and give it at least the recommended 24 hours, and you should have pure, clear, algae-free pool water again.

And again. And again, because the bulk pack means you won’t run out practically all pool season!


  • This is chemically hardcore, with high concentrations of calcium hypochlorite
  • It destroys algae, bacteria, and all the chemistry we add to our bodies before jumping into the pool
  • It dissolves fast and gets to work in a hurry


  • The sediment can be a little disturbing initially


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If you’ve never come across the brand – with an infuriating difficulty to pronounce – calls itself hth, you haven’t been looking for top quality pool shock for very long.

It’s a brand that stands out not just for its quirky name but because it delivers some hardcore pool shocking action at a reasonable price point in the market.

With a 56% concentration of calcium hypochlorite in every pound of shock, it’s technically less dramatic than the likes of the DryTec, but you’ll still get impressive results within 24 hours of running this shock through your system.

And, like some of the higher-ranking shocks, it will clear up your water without overstabilizing your pool.

This is a standard 6-pack, chosen for the reasonable price-point, but you might as well buy the 6-packs in bulk to get you through the whole of pool season.

There’s no fuss, no muss, no measuring with this shock, you just open, pour the pre-measured amount into your pool and let the calcium hypochlorite do its job.


  • This shock dissolves fast and gets to work rapidly, so that within 24 hours, you’re seeing results in your pool
  • There’s less eye irritation with the hth shock than there is with some other leading brands
  • It doesn’t overstabilize your pool in the process of killing all the algae and bacteria


  • To boost consumer confidence, it could dissolve more effectively without help


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Taking on the DryTec shock at its own game, In The Swim brings its 68% calcium hypochlorite shock to the market, and it’s a thing of pool cleaning joy.

Taking a leaf out of hth’s book, the In The Swim shock comes in individual bags containing pre-measured amounts of treatment.

That makes it fuss-free and ready to go at the drop of a shock-bag.

What In The Swim brings to market here is a solid, reliable, regular maintenance regime, with a chlorine boost to boot.

Algae and bacteria don’t stand a realistic chance against a 68% concentration of calcium hypochlorite.

One thing we’d say though is that if you have a vinyl pool, the In The Swim is probably not your ideal go-to shock.

But if you have any other sort of pool, you’d struggle to go wrong with the In The Swim 6-pack. 

And while there’s something to be said for buying in greater bulk at one time, the In The Swim 6-pack is very reasonably priced, so unless you have a larger pool than 10,000 gallons (for which, a 1 pound bag will be quite enough), you could do a lot worse than simply stocking up on this shock and having it in hand throughout the whole of the pool season.

Just add 4 (or 5, to be safe) to your shopping cart and boom – all the shock you need for a hot girl/boy/non-binary groover summer in and out of the pool.

Naturally, we wouldn’t recommend products simply on the basis of their brand, but what you have here is a highly effective shock with some powerful algae-killing chemistry that also just happens to be from a leading brand in the market.

So there’s a degree to which the brand underlines the confidence you can have in the product.

But there’s not a real need to fall back on the brand here, because the product does what it claims to do, and will give you easy, no-hassle results when you next need to shock your pool.


  • In The Swim has made its packaging easy, meaning there’s no mess, no fuss, and no need to measure out precise doses of its shock. Just empty the pre-measured bag into the pool and let the games begin.
  • This shock contains a high level of calcium hypochlorite, matching the higher-rated DryTec, but at a lower price point
  • This is a highly cost-effective pool shock that could see you all the way through pool season without breaking the bank


  • Peculiarly, this shock is no friend to those who have vinyl pools, and should not be used to shock those pools

Best Pool Shock Buying Guide

When you’re buying shock for your pool, it helps to keep a handful of things in mind before you click on the “buy” button.

Best Pool Shock

Stabilized Or Unstabilized

There are differences between stabilized and unstabilized shock.

If your shock contains sodium dichlor, what you have is usually a stabilized pool shock, so the chlorine is protected from the sun, and you can use it during the day. 

With unstabilized shock, you have to apply it at night, so the UV rays don’t dissipate the chlorine too quickly.

Choose Your Chlorine Hit

Most of the best pool shocks will contain chlorine. In fact, it’s usually a major ingredient behind the algae and bacteria-nuking action of your shock.

But not all chlorine shocks are the same. The higher the percentage of chlorine, the more effective the chemical bomb of your shock.

But it’s not as simple as just dialling up the chlorine to 11 and walking away.

Sometimes, too much chlorine will mess with your water’s chemistry or pH levels. If you can find shocks that protect your water’s pH balance, you’re in a good place, and can afford to go heavy on the chlorine.

Powder Or Liquid Shock

Most pool shocks out there are sold in powdered form. That means you have to pre-mix the shock before you add it to your pool.

On the other hand, if you can find a liquid treatment, you cut out the time-consuming pre-mix and go straight to a product you can just pour straight into your pool. We know which we’d go for – and so do you.


Technically, it’s slightly absurd to look for a pool shock that’s free of additives. After all, pool shock is an additive, that’s the definition of what it is.

But you should probably keep an eye open for the potential effects of the chemistry of your shocks on the water in your pool. Calcium hypochlorite is – entirely unsurprisingly – going to add more calcium to your pool water.

Sodium dichlor on the other hand adds cyanuric acid to the water, which is – at least a little – less disturbing than it sounds.

If you can minimize the impact of the additive chemicals in your shock and keep it simple, you’re winning at pool shocking.


There’s pool shock, and then there’s pool shock. Some of the sodium dichlor shocks claim to be effect-free within minutes. Others caution you to wait 24 hours before getting in the pool.

Invest in a chlorine photometer to allow you to do rapid, definitive tests for the chlorine levels in your pool, so you cut out the guesswork.

Frequently Asked Questions

Is Stabilized Or Unstabilized Shock More Effective?

Neither – it’s just a question of when you use it. Stabilized shock can be used in the daylight, because its chlorine is protected from the effects of UV sunlight.

Unstabilized shock is a night treatment, because UV light would dissipate its chlorine.

Is It Worth Bulk-Buying Shock For Pool Season?

Probably, yes – shocking is something you have to do at least every two weeks during pool season. Why leave yourself short when you need it?

Will Shock Really Get Rid Of Things Like Make-up And Body Oil From The Pool?

Usually, so long as it’s labelled as a flocculant, as well as killing algae and bacteria, yes.