Knowing how to shock a pool is one of the essential pool maintenance tools that every pool owner needs. It’s a simple procedure, but you need to be highly aware of what’s involved so that you and other pool users stay safe!
Here’s how to shock a pool:
- Identify pool problem (stinging eyes, itching skin, or build-up of cloudy or green water)
- Decide on chlorine shock treatment vs non-chlorine shock
- Measure the correct amount of the desired shock treatment (1lb for every 10,000 gallons of water, or to double shock, 2lb for every 10,000 gallons of water)
- Apply to pool
- Test your pool chlorine levels – you’ll need to keep your levels at between 10ppm and 30ppm for several hours
- Check the result
- Test again – you’ll need the chlorine levels to have dropped to under 3ppm for safety
- Repeat the process to shock again if required!
That’s how to shock a pool, but here’s what you need to know in order to undertake this practice safely, and to make sure it works the first time around.
What Is Pool Shocking?
Pool shocking is using a 3-5X the normal amount of your chemical sanitizer in one go, in order to ‘shock’ your pool and get rid of undesirable qualities in your pool, such as green water.
Some pool owners make the mistake of shocking it at the first sight of green, or when they experience mild signs that something might not be quite right, such as your eyes are stinging! There could be a number of causes for the multiple types of pool problem, and shocking your pool automatically might not be the best solution in the long run – and at worst could cause pool damage if done too often.
So to know how to shock a pool, you’re going to want to know first more specific information about what it is, and how it works. That way you can understand exactly when it’s required, and how to use it safely as an effective pool treatment.
Pool shocking is also often known as ‘super chlorination’, and it’s super-effective at eliminating waste products in your pool such as oils left by sunscreens.
To achieve successful super chlorination, a single large dose of chlorine is applied to the water. Super chlorination actually works by first reacting with the organic wastes in the water to form more combined chlorine.
Once a sufficient level of chlorine has been added, all of the organics will have been reacted with (oxidized), and only then will the combined chlorine break down leaving free chlorine. Typically, the amount of chlorine required is ten times the level of combined chlorine in the water. For example, if the chlorine test shows a level of 1.2 ppm of combined chlorine you will need to add 12 ppm of additional chlorine in order to destroy all of the combined chlorine.
While most pool owners use chlorine to shock their pool, if you’re shocking your pool too frequently you might experience pH imbalances, which can lead to issues with eyes, skin, and health.
Chlorine overuse can also cause issues for your pool liner, deck, and surrounding areas, and your equipment – this is why I mentioned at the beginning you really need to research properly if you want to know how to shock a pool, as you don’t want to be just dumping in a load of chlorine at the first sign your pool is a little green!
However, you can also shock your pool without chlorine. Now, there are products available that can help you achieve the same results but with less ‘wear’ on your pool than you might experience with traditional chlorine.
However you choose how to shock a pool, if you don’t shock too often and stick to the guidelines, your pool won’t suffer whichever shock method you choose.
How To Shock A Pool Without Chlorine?
Shock oxidation treatment is a phrase commonly used when referring to the use of a product that does not contain chlorine, but you are still performing the pool shocking process. Instead, the process uses a unique oxidizer to work, or ‘non-chlorine shock’.
The non-chlorine shock uses an oxidizer that will directly oxidize the waste itself, whereas chlorine used in super chlorination works by first changing the waste into combined chlorine before the final breakdown.
Since non-chlorine shock oxidizer does not require chlorine, it can be used to destroy waste and even debris, before they have a chance to form combined chlorine; the advantages to using it are:
- does not require excessive chlorine use
- will not harm pool liners
- will not upset water balance
- easy to determine needed dosages
- can swim as soon as 15 minutes after treatment
How Often Should You Shock Your Pool?
When considering how to shock a pool you’ll want to know how often you need to do it! You’ll want to give the pool a good shock at the start of the spring/summer season for sure, to clear out any nasties and get the water all fresh and ready.
How often you shock your pool after that really depends on how much your personal needs it – factors that could signify you need a shock treatment include:
- heavy rains leading to debris and grime in the water
- how many swimmers (increased swimmers lead to more oils and body grease)!
- time of year (some months will naturally have less human load)
- the weather
- your pool location (trees around your pool will lead to more grime and debris)
- presence of combined chlorine
- any extreme discoloration eg vivid green
- algae visibility
Most pools are shocked every two or three weeks, but you can leave it up to a month if you’re not using your pool frequently.
It’s also useful to shock your pool after a heavy storm when your pool is likely to contain unexpected grime and debris. Shock oxidation treatment following a heavy rain will help to treat these problems.
How To Shock A Pool With Chlorine?
To properly learn how to shock a pool you need to learn how to get down and um, clean with the world’s most popular pool cleaning chemical.
You’re going to need to know a little about this in order to stay safe while using an extra-large dose of it! – what you might not know is what exactly is, how to really use it safely, and how to use it to get the result you want – (most important)!
What Is Pool Chlorine, Exactly?
Chlorine is a chemical pool cleaner and sanitizer that comes in multiple forms – tablet, powder or liquid form, which you add to your pool after a little prep work. Adding chlorine to your pool, whatever form it takes, is the main ingredient in keeping your pool healthy enough to swim in and looking good too.
Chlorine protects against:
- Micro-organisms carrying often deadly diseases (including dysentery and other deadly diseases you thought had died out in the middle ages).
- Sweat, saliva, multiple forms of oils (sunscreen), deodorant, body creams, and dirt from people swimming in the pool
- Dirt and debris from the pool surrounds and deck
Any growth and spread of algae (more about this later!)
How Chlorine Works?
Once the chlorine is added to your water, it forms a new substance called ‘hydrochloric acid’ which disables harmful bacteria, viruses, and other microscopic dangers by combining with them.
Combined chlorine is also known as chloramine. Hydrochloric acid, despite its name, is much less harmful to us than the diseases we are trying to prevent!
The process of chlorination only works when your pH levels of the pool are correct.
How To Shock A Pool To Prevent Chloramine Build-Up?
Remember when I told you chlorine combines with the harmful stuff in your pool to create new compounds called chloramines?
Well, as more chlorine is added to your pool, these chloramines (also called combined chlorine) begin to build up in the water.
This build-up is a problem because chloramine:
- Gets in the way of chlorine, slowing down the cleaning and filtering processes.
- Causes skin and eye irritation in pool users.
- Is responsible for that overpowering “chlorine smell”
The solution is to shock your pool, which requires adding even more chlorine to fix the problem.
However you need to know that if you don’t use enough chlorine to reach breakpoint you can actually make the problem worse as it will only create more chloramines. If that happens, you’ll need even more chlorine to reach the breakpoint.
So here are my top tips on how to do this, and how to shock a pool safely and easily!
How To Shock A Pool – Top Tips
Super chlorinating your pool water keeps pool water safe and clean by adding three to five times the normal amount of chlorine or other chemical sanitizers to the pool water to drastically raise the chlorine level, for a short time.
This will help to remove ineffective chlorine amounts, kills bacteria and anything else that doesn’t belong in the pool (grime, slime, bugs), and boosts the availability of effective chlorine.
Pool shocking sounds like an intensive process but really it’s just adding extra chemicals in order to flush out the undesirable build-up of other ones and all of the other things you don’t want floating around in your pool water.
Shock the pool regularly
Keep an eye on your pH levels and your chlorine levels in the pool. Even if everything looks good to you, pool shocking is still beneficial for your pool at least every month and even more for a heated pool or spa pool – and remember if your pool is near a particularly leafy area, or you’ve just had a spate of storms or bad weather – shock your pool on a fortnightly basis.
Shock after the sun has set
This sounds a little like an old wives tale or an urban myth, but sunlight genuinely does impact the chlorine from working, which is why if your pool is in direct sunlight you’ll possibly find that you need to top of chlorine far more frequently than you expected.
Dissolve the pool shock chemicals
Your packet or bag of pool shock treatment dissolves easily – you’ll need to add it to a bucket of water before pouring it into your pool. Make sure you add it to the bucket of water and not the other way around as chlorine can be hazardous when water is added to it. Mix the chlorine pool shock treatment with your water well before pouring it slowly and carefully into the pool.
For the best place to add it, look for where your water is returning into your pool. This will ensure that you get a great dispersion of the chlorine and that it spreads out to all areas of your pool and does not clump into one area.
Ensure that you pour slowly so that your shock treatment does not end up splashing your desk, pool surrounds, or anywhere else nearby where it could be a potential health hazard – as well as ensuring people, children, pets nearby are safe.
Not to mention the damage it can cause to your surrounding areas! Lean close to the water’s edge – obviously not too close, you don’t want to fall in holding chlorine shock treatment! – and pour slowly most of the mixture.
Once you get almost to the bottom, about a quarter left, refill the bucket with water, and stir again to dissolve any extra grains which did not dissolve the first time.
Pour this extra mixture in the same way as before.
The one thing you want to avoid is seeing any granules anywhere – this signifies that the mix has not fully been dissolved. If this happens grab your super-handy telescopic pole and a brush and sweep the grains until they vanish – keep sweeping and stirring your pool until all the grains have gone.
Obviously, at this point your pool is not safe to swim in! Keep testing your pool until you get a reading of the chlorine being at 3ppm or less. Only at this point is your pool safe to swim in.
You can also use your automatic chlorine dispenser to shock your pool. Just make sure you keep check on the chlorine levels and ensure again that all of the grains are gone before anybody swims in the water.
Do check your manufacturer’s label before shocking your pool to ensure you are using the right quantities.
Chlorine shock is simply un-stabilized chlorine which is exactly what chlorine bleach is that you buy from the supermarket. You can use this instead by working out the amounts for your pool (approx. 4L of 5% hypochlorite chlorine bleach per 10000L of pool water) Make sure you buy non-fragranced chlorine bleach, you want just pure hypochlorite.
Check the pH range before shocking. It needs to be within the normal range before shocking, otherwise, the extra chlorine can oxidize copper parts in the pool. If this happens, black stains will appear on the water surface.
Bear in mind that it is better to add shock chemicals in small amounts at multiple locations across the pool rather than dumping in a large quantity and hoping it will disperse evenly. If you have a vinyl liner in your swimming pool, you cannot allow un-dissolved pool shock to settle to the floor, because this may bleach or stain your pool liner.
Not to sound like the pool safety police here but here are some reminders on how to chlorine shock safely. Chlorine, after all, is a toxic chemical!
How To Shock A Pool Safely?
- Always add your chemicals to the water, not the other way around. Do not add water to chemicals! And never pour pool shock into the skimmer, pre-dissolve for use in vinyl liner pools.
- When distributing shock across the surface, be mindful of the wind direction.
- Brush the pool after shocking, and filter the water for at least 8 hours afterward.
- If chlorine level is zero within 8 hours of shocking pool, shock pool again, with more chlorine this time.
- Pool shock can still be hazardous to health. Make sure you use it in a well-ventilated area, you keep testing the water, and you wear protective equipment.
- Add Pool shock separately, it can destroy or disrupt other treatment chemicals.
- Never allow pool shock to become hot, moist or contaminated with dirt or debris.