Best Pool Shock 2019 – Reviews & Buyer’s Guide

using shock to clean our pool

The shocking truth about swimming pools is that they can’t always be kept crystal clear and free of algae just with slow, measured additions of chemicals. This sad truth includes spas and hot tubs too. Slow and steady might win the race for the tortoise when he’s racing against the hare, but that ain’t happenin’ against algae.

Bacteria and algae spores carry with them a built-in exponential growth rate. Once they get beyond a certain tipping point you’ll suddenly get foul-smelling or green water overnight. The only way to prevent it, or stop it once it happens, is to shock the water in your swimming pool with a huge burst of chlorine.

There are a lot of different brands of shock on the market, and not all brands are the same. There’s no such thing as pure chlorine, and the additives can make it either acid or alkaline, depending on what they are. So how do you decide which one is best for you?

Easy. You read our reviews where we’ve already compiled all the information you’re looking for and need in order to make an informed decision. That’s what they’re here for.

Our Favorite Picks Compared

ModelPriceWeightEditor Rating
In The Swim Chlorine Pool Shock (24 bags)
In The Swim Chlorine Pool Shock (24 bags)
(Top Pick)

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25 lbs4.95/5
Doheny’s Super Pool Shock (24 bags)
Doheny’s Super Pool Shock (24 bags)

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24 lbs4.8/5
Clorox Pool&Spa Shock Xtra Blue 33012CLX
Clorox Pool&Spa Shock Xtra Blue 33012CLX
(Best for the Money)

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12 lbs4.7/5
Aqua Chem 12101AQU-02 (10 Pack)
Aqua Chem 12101AQU-02 (10 Pack)

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10 lbs4.3/5
Ultima 24726 Total Control
Ultima 24726 Total Control

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3 lbs4.0/5

5 Best Pool Shock – Reviews 2019:

1. In The Swim Chlorine Pool Shock (24 bags) – Top Pick

In The Swim Chlorine Pool Shock (24 bags)

Once a week, sprinkle this on your pool at the rate of one bag for every 10,000 gallons, and you’ll be a happy camper. Do the same thing the day after a heavy rain or storm. It works to kill harmful bacteria that are constantly trying to invade your pool, and prevents algae from turning your water pea soup green.

This dry, powdered shock dissolves quickly in water. For best results, sprinkle it evenly all around the pool. If your pool is big enough to require more than one bag, try to distribute it around the pool on a per bag basis. For instance, if you need two bags, spread one bag around one half of the pool and the other bag on the other half.

This ensures good distribution as it dissolves and prevents localized buildup that might eat the liner of your pool. Chlorine is good for swimming pools, but concentrated chlorine can eat rubber like a dog wolfing down your lunch when your back is turned. Spread it around to keep that from happening.

This provides a powerful and effective shock treatment to overcome stubborn algae and bacteria that slower-acting chlorine tabs just can’t handle.

  • Prevents algae
  • Dissolves quickly
  • Quick chlorine boost
  • Kills harmful bacteria
  • Powerful and effective
  • Heavy concentration eats rubber

2. Doheny’s Super Pool Shock (24 bags) – The Runner-Up

Doheny's Super Pool Shock (24 bags)

The selling point here is that this shock is good for pool openings after a long winter. It is intended to shock the water into crystal-clear clarity in a matter of days, killing bacteria and algae, then preventing any more from taking up residence in your swimming pool.

The other selling point is supposed to be the low price. Doheny apparently wants to be the low price leader. Unfortunately, not all low prices are as good as they sound. In this case, it’s not.

While it does a reasonable job of killing harmful bacteria in the water and keeping algae away, it has a regrettable tendency not to dissolve all the way. One of the additives in the mix leaves a residue at the bottom of the pool, and sometimes floating on the top. This can also leave the water looking a bit cloudy. Additionally, it seems to require more shock than the top pick to get the same results.

Like any shock, you need to spread it around for the best results, and to avoid a heavy concentration of chlorine that could damage the liner in your swimming pool.

  • Low price
  • Kills bacteria
  • Quick chlorine boost
  • Good for pool openings
  • Doesn’t dissolve all the way
  • Heavy concentration eats rubber

3. Clorox Pool & Spa Shock Xtra Blue – Best for the Money

Clorox Pool&Spa Shock Xtra Blue 33012CLX

Clorox is a well-known brand for everything from kitchen cleaners to swimming pool chemicals. Given the size of this company, it can easily afford to offer economies of scale to customers. This would explain how it can offer an effective shock at a low price.

The bottles are easy to open, and arguably give you more control over where you spread the contents than the bags do. The bottles are also resealable if you’ve got a small pool that doesn’t require the whole bottle. This is a small but very nice feature that will save you some money.

It kills algae and bacteria reasonably well. But if you find it’s not doing anything for your pool, or your water starts turning green, check the expiration date. Clorox apparently has a habit of shipping out products even after they’ve passed their expiration date. This creates a problem where older chemicals don’t do their job, algae and bacteria build up in your pool, the water turns green, and you wind up spending way too much money to fix the problem.

It’s good for the price, but keep an eye on those expiration dates.

  • Nice container
  • Well-known brand
  • Works reasonably well
  • Watch the expiration date
  • Older chemicals don’t work
  • Heavy concentration eats rubber

4. Aqua Chem 12101AQU-02 Pool Shocks (10 Pack)

Aqua Chem 12101AQU-02

This is an expensive, chlorine-based shock with a little bit of copper-based algaecide thrown in for good measure. Although the advertising claims to reduce chlorine odor and eye irritation, it mainly seems to do it by not working. This is a weak product that falls short in many areas.

At first, it seemed to work decently as a pool shock, only to have all the blue color in it wind up in the cartridge filter. It created a gigantic mess that took several tries to finally wash away. A sand filter might not catch it, so it could conceivably wind up right back in your pool. If you want to be our experimental guinea pig on this one, feel free to give it a try.

In addition, the copper in the shock can play havoc with the copper levels in your swimming pool, to the point where that has to be addressed before anything else.

This shock does kill some bacteria and algae, but the side effects make it more trouble than it’s worth. Unless you have a lot of spare time to waste monkeying around with the chemical levels in your pool, try something else.

  • Contains algaecide
  • Kills some bacteria
  • Weak product
  • Fairly expensive
  • Messes up cartridge filters
  • Creates havoc with chemical levels

5. Ultima 24726 Total Control Pool Shock

Ultima 24726

This product contains shock and algaecide in the container. It claims to prevent green and black algae, as well as improving water clarity. Although the label doesn’t list it prominently, it does contain copper sulfate.

This is a granulated product, instead of a fine powder like most chlorine shock. This translates into a slower dissolve time once it hits the water in your pool. It gets there eventually, but it won’t be nearly as fast as you’d like.

It does work to a certain extent, but it’s not going to impress anyone in the process. The algaecide isn’t as strong as stand-alone algaecides that you buy separately, and neither is the shock. There’s enough of both that they do work a little, but not enough of either that they can do an outstanding job. It’s sort of “the worst of both worlds.” Even using more than the label recommends doesn’t produce any noteworthy results.

The copper in it can create problems with the copper levels in your water just like number four on our list above. There’s simply nothing interesting about this product. Don’t waste your time or money on it.

  • Contains shock and algaecide
  • Weak product
  • Granular product
  • Dissolves very slowly
  • Copper creates problems
  • Waste of time and money

Buyer’s Guide

Shock is one of those products that has little or no expectation of a return policy of any kind. Generally speaking, once you buy it, it’s yours. That’s one of the reasons reviews like these are such money savers. Who wants to get stuck with a bunch of chemicals you can’t use and can’t get rid of?

Shock is also one of those products like gasoline whose price is subject to change at a moment’s notice. One day you can buy gas at one gas station for a low price, and the next day you find it across town for even less. It happens. Shock is the same way.

Just because you can get it for less online today doesn’t mean it won’t cost less at your local swimming pool store tomorrow. Once you figure out which shock is the one for you and your pool, take a few minutes to do a little price shopping. You’d be surprised at the savings you can find if you try.

If possible, buy in quantity. Everyone offers quantity discounts sooner or later. Some outlets even offer them 24/7. If you can afford a little extra out-of-pocket expense right now, it’ll save you quite a bit over the long run.

What makes a good shock?

A good shock should dissolve quickly. The whole point of shocking your pool is to give it a quick, powerful burst of chlorine to kill any harmful bacteria and to throw up a roadblock to any type of algae that’s trying to establish a foothold in the water. Shock that dissolves slowly is going to act slowly too, or not at all.

A good shock should be as close to pH neutral as possible. None of it will be perfect, but the closer it is to the center line, the less you’ll have to mess around with pH increasers or decreasers. Less time horsing around with chemicals means more time horsing around in your swimming pool for fun. And that, after all, is the whole point of having a swimming pool in the first place.

Shock should also be free of additives that leave behind a residue that has to be cleaned up. Some shock, unfortunately, does leave a residue behind, requiring cleaning – vacuuming or skimming – before you can use your pool.

Shock that contains algaecides or copper additives can reduce the effectiveness of the chlorine. Those other chemicals can, and should, be added separately. They’re much easier to adjust when you don’t have to worry about increasing or decreasing some other chemical at the same time.

Remember the old acronym, KISS – keep it simple, stupid. Adherence to this principle pays dividends when you’re adjusting the chemicals in your pool.

Available Options

The need for shock implies the need for other chemicals, as well as other equipment. If you’re buying online, you can save yourself a lot of shipping charges by throwing several items together in one order. If you’re buying at local swimming pool stores, they sometimes offer discounts on orders over a certain price range. Either way, you win. Let’s look at some extras you might need.


As mentioned earlier, products that combine chlorine and algaecides are a bad idea. Increasing one means you’re increasing the other, not always a good idea. Keeping them separate avoids those complications.

Once you’ve got the chlorine levels in your pool dialed in, you can throw in however much algaecide you need without having to worry about overdoing it on the chlorine, or vice versa. Separate chemicals allow for much greater precision, which in turn yields better results.

pH adjustments

The water in your swimming pool should ideally have a pH value of 7.2-7.6. When it doesn’t, the water can become cloudy, bad-tasting, bad-smelling, or all three. Chemicals for adjusting the pH in your pool up or down are generally known as pH increasers or pH decreasers.

They go by a wide variety of names from different manufacturers, but their purpose is the same: to raise or lower the pH value of the water in your swimming pool until it returns to normal.

You don’t need large quantities of these chemicals, but you do need them. Buying them at the same time as your shock only makes sense. Once you’ve got them on hand, they have a very decent shelf life and you’ll have them on hand any time you need them.

Chlorine tabs

Shock alone won’t keep your pool in usable condition. You need a steady supply of chlorine entering the pool in between shock treatments. Chlorine tabs provide it in the form of compact 1-3″ tabs that sit in your skimmer or inside a float, slowly dissolving over a period of days.

A 25-pound bucket of chlorine tabs can last most of the summer, or even longer if you keep the water in your pool properly balanced and treated. Go ahead and grab some while you’re at it.

A floater – a plastic device for holding a chlorine tab while floating free in the pool – can be a valuable addition to your arsenal for keeping your pool in pristine shape. They’re fairly inexpensive, so toss a couple of them in your basket on the way to the checkout.

Test kits

You need to test the chemical levels in your swimming pool’s water. You probably have a test kit already, but if you don’t, or if it’s time to get a new one, why not throw it in with your order of shock? There are a number of good test kits available on the market today, any one of which can help you pin down exactly how much of each chemical you have in your pool.

Precision in chemistry is like precision in the kitchen. If you don’t add enough of each ingredient to your cake batter, it won’t taste right. It might even be so bad the dog won’t eat it. Test kits help you achieve that precision. A test kit with a digital readout is better still.

Pool cleaning equipment

There’s a wide variety of pool cleaning equipment, from handheld manual skimmers, brushes, and leaf bags, to fully automated robotic cleaners that crawl tirelessly across the bottom of your pool sucking up dirt and debris. Shock is only one way of keeping your pool clean and sanitized. Scrubbing the bottom and sides of the pool, then vacuuming it out, can make life easier for the chemicals you’re throwing in the water. Combining physical cleaning with chemical cleaning can work wonders.

Any time you go to the swimming pool store or do your shopping online, take a moment to visit the cleaning equipment just in case something you need or want is on sale that day. Sales come and go. If you catch one at the right time you can get some great deals.


Shocking the water in your swimming pool is standard procedure if you want that movie star quality pool. Bacteria and algae never quit and never give up; you shouldn’t either. These reviews were designed to help you get ahead of the curve by making the best decision for you and your pool.

The top pick is In The Swim Chlorine Pool Shock (24 bags). Each one-pound bag contains enough shock for 10,000 gallons of water and will do the job you’re looking for. It kills bacteria, prevents or kills algae, and clarifies the water. The result will be a pool to be proud of.

The best for the money choice is the Clorox Pool&Spa Shock Xtra Blue 33012CLX. This is your inexpensive choice for swimming pools. The bottles are easy to open and make distributing the chlorine evenly quick and simple. Keep an eye on the expiration dates, though. Older products sometimes get shipped out.

Hopefully, you’ve learned from the work we put into these reviews and can take what you’ve learned to the store or the website to get the brand of shock that’s best for you. If this helps you make a good decision, our job is done.