How much bleach for a 10000-gallon pool?

Hello and thank you for reading another blog, this article is about how much bleach you should add to a swimming pool to make it safe to swim in. Even if you have a chemical free-swimming pool, you must also clean it.  The key for all swimming pools above ground, indoor, outdoor is the same keeping the pool water clean. We will discuss “How much bleach for a 10000-gallon pool?” deep in this blog.  

Bleach is the first chemical to think of for cleaning a swimming pool. Let’s face it most of you buy bleach to clean the bathroom so it makes sense to use it for pools, right? Using bleach has been the easiest way to maintain a required level of chlorine for many years. You need to first check the chlorine levels to determine the required level of bleach you need to add to the pool to reach the ppm zone of 3 to 5 ppm. This will need to be repeated regularly to obtain a clean safe pool. 

If you browse the World Wide Web you can see thousands of images of beautiful crystal-clear swimming pools, you look at the image and think that looks easy I can have my pool looking like that.  Well, you can with many sanitization methods that use chemicals and chlorine. You can obtain this also with chlorine free swimming pool systems that we will discuss in another article. 

Most people don’t know what the bleach, chlorine

Does to your pool water, how it works and why do we need it? Well, the chlorine in its liquid form is an excellent oxidizer. It will however dissipate over time with heat and UV, so it normally requires a secondary sanitizer in the form of another chemical, or equipment. 

So now to the point how much bleach to use? To calculate this, you need to know the chlorine level of your pool, and the best way to do this is to order a ph and chlorine level test kit. Ideally you are looking at a level of between 1 to 3 part per million for the water to be safe to swim in. Most bleaches have a high concentration of around 5.7%, so to calculate this on a pool that is say 5000 gallons you will require around 24oz to raise the chlorine to the correct level. 

For more of a precise measurement, you need to measure the pool by multiplying the length by the width by the the relative depth of your pool and this with give you the sum of the estimated volume of water. 

If your pool is round you need to multiply the volume sum by 5.9. If your pool is a rectangular shape multiply it by 7.5 gallons and if it is more of an oval pool shape multiply it by 6.7. This will give you an estimate of how much water your pool holds. 

Once you have this figure then the rule of thumb is you will need around ½ gallon of bleach for every 10,000 gallons of water to increase the chlorine level by 5 parts per million. 

If your pool  is an outdoor pool and is exposed to sunlight and in a fairly moderate climate, we found with the chlorine level for around 3 ppm is suitable to take into consideration temperatures, possible downpours of rain and the CYA level in the pool (Cyanuric Acid ,like a sunscreen for chlorine). If you are in a warmer climate or you have a very unusual hot spell it’s advisable to add around 5 ppm and expect to lose around 2 ppm due to due to the evaporation. Even if you have added bleach to the swimming pool water you will still need to add a small amount of stabilizer so the harsh direct sunlight does not evaporate the bleach you have just added. This is a straight forward operation and not too difficult and you should be able to work out how much CYA you need to add to your swimming pool water. 

Now you have worked out the size of your pool you can now get down to adding the bleach to bring your chlorine levels to the required level for a safe swimming. Below are some common pool sizes based on the water volume, and we have included a guide for the amount of Bleach required to raise the swimming pools water by 1 ppm. 

5000 gallons or 22730 ltrs you need to add 10 ounces or .295ltr 

7500 gallons or 34096 ltrs you need to add 16 ounces or .473 ltr 

10000 gallons or 4546 ltrs you need to add 21 ounces or .621 ltr 

15000 gallons or 6819 ltrs you need to add 31 ounces or .916 ltr 

20000 gallons or 90922 ltrs you need to add 41 ounces or 1.21 ltr 

Adding Bleach  

Most pool suppliers tend not to promote the use of chlorine on its own as a bleaching agent. They would prefer you to buy a concoction of bleach and water-based products. Some shops heavily promote chlorine tablets with other options such as ones with stabilizers. This type of chlorine tablet releases the chlorine at a slower rate into the pool and obviously makes it last longer. The issue of releasing the stabilizing bleach into the water means there is more chance of the bacteria reforming and not being removed from your pool.  

The chemicals use in the tablets break down very slowly and the problem is that you cannot control how much chlorine is actually going into the swimming pool water. Also, we have known when you add fresh chlorine via the tablet, this then attacks the existing tablets and not the actual bacteria you are trying to eradicate.  

The best solution if you have to use bleach is to use it in liquid form. 

What is bleach? 

Liquid bleach has been around since 1785 so it is very old and to be honest is now classed as a harmful and damaging to the environment and your health. It was developed by a Frenchman named Claude Louis Berthollet and he then sold it to a company and they renamed it Liqueur de Javel. The main use of this new product was for bleaching cotton and then soon became a popular for it use in bleaching other textiles at room temperature. Over the years other uses have been found for bleach today most people know bleach as a way of cleaning their kitchens, bathrooms and where that needs to be sanitized and the bleach can be washed away after it has carried out its sanitization purpose. 

Liquid chlorine and bleach both have the same ingredients which is sodium hypochlorite which gives them identical water purifying properties. The biggest difference between the liquid chlorine and the bleach is that the bleach will be much more diluted and you will require a higher amount to add to your swimming pool compared to using the Chlorine. 

Domestic or household bleach is a mixture of chemicals of which the main ingredient is sodium hypochlorite (Na0Cl). This consists of sodium hydroxide, hydrogen peroxide, and calcium hypochlorite.

Dangerous side reactions 

Bleach is generally safe if handled carefully and stored away from children. In 2002 it was estimated there were over 3310 incidents with people have contact with either drinking or getting bleach onto their skin.  

The Sodium hypochlorite in the bleach reacts very rapidly with sunlight to produce chlorine gas which in an enclosed area such as an indoor pool can have a severe effect on someone’s lungs and breathing. In the first and second world war the Axis powers used this as a weapon.  

Benefit of using bleach  

The cost of purchasing bleach is the biggest advantage and possibly the only advantage. As it’s often used in the home you will find bleach in just about any supermarket more than likely to be cheaper than buying from an authorized swimming pool store. Try not to purchase in bulk as you need to use the bleach as fresh as possible to give the maximum oxidising effect on your swimming pool water. 

Storing Bleach 

As we mentioned earlier in this blog bleach is a dangerous chemical-based liquid. Try to keep the bleach near the pool or in a pump room far away from children. The bleach should last up to six months if it’s kept in a dry cool area. It will still work after six months but not as effective. 

Closing thoughts 

Liquid chlorine, bleach, chlorine, bleach tablets are all based on using chemicals with the main aim of reducing or increasing the parts per million in your swimming pool water to get the safest level to enjoy a relaxing swim in your pool. 

You have to decide if you want to use this form of swimming pool sanitization that has been around for many years, which is a proven and very cost-effective way of enjoying your pool. The other point to consider is to use other modern forms of sanitization that do not involve using toxic, harmful chemicals. Have a think about it. I think if you understand the reality you will never have to think about “how much bleach for a 10000-gallon pool”.