Should I Shock My Pool When I First Fill It Up?

Having a good understanding of the term “Pool Shock” will help one to know that it’s one of the most important maintenance practices needed for pools. Pool shock can also be called super chlorination. Constant shocking of your pool is a simple way to prevent bacteria and algae from breeding and growing on your pool water.

So should you shock your pool when you first fill it up? Yes, pool shock is very important as it helps to destroy organic wastes and makes the water look polished. The pool shock helps to boost the efficiency of the sanitizer as it keeps the organic wastes from interfering with the sanitizer.

The last time you walked past a crowded pool, you felt a smell right? A mixture of chlorine with nitrogen in oils, sweat, and urine causes your pool to smell. You may think that the smell is a result of chlorine in the pool. The odor comes from a mixture called chloramines. Having chloramines in your pool is a sign that the water is not balanced. Too many chloramines not only causes smells but also causes eye and skin irritation. It also causes respiratory problems.

Pool shock prevents your pool from getting foul smells. When you learn to and constantly shock a pool, it will become a routine.

What is a pool shock?

Super chlorination or pool shock refers to the introduction of chemicals, most times the powdered form of chlorine (granular oxidizer), and other chemicals used for cleaning to destroy chloramines and get rid of organisms in the water. Bromine is also used as a pool shock. Pool shock is used most times because a lot of harmful materials pollute the pool and alter the water balance when they get into the pool.

In summary, you will constantly need to shock your pool for the following reasons; To

  • Quickly raise the chlorine level when the sun breaks down or heavy rain dilutes the chlorine level in the pool
  • Prevent having a smelly pool.
  • Avoid eye and skin irritation.
  • Break apart chloramine, also known as combine chlorine.
  • Kill algae, bacteria, and other harmful pathogens.
  • Removes contaminants from make-up, leaves, air pollution, sweats, organisms, and specks of dirt swimmers and wind constantly bring into the pool.
  • Prevent sickness caused by bacteria from swimmers.

If you are new to it, pool shock may seem difficult and scary. Handling chemicals that may burn the skin and cause irritation if not properly handled can make anyone feel jittery. But trust me, when you constantly shock a pool it gets easier.

When to shock your pool

You don’t want to wait to see cloudy pool water, have an overgrowth of algae, feel a bad smell or have itchy eyes when using your pool before you shock it. Overgrowth of algae stains the wall of the pool, so cleaning of overgrowth requires draining of the pool before scrubbing. When this happens, it will take a lot of scrubbing and disinfecting to get the pool clean. We recommend shocking your pool every week, or fortnightly. This is to have the right of each chemical in your pool water. The more often you use the pool, the more often you should reach for the pool shock.

So if you constantly shock your pool (every week or fortnightly), you will be able to prevent sickness caused by algae and other bacterias. Even if you constantly shock your pool, you may want to perform an extra pool shock under these circumstances;

  • After extreme weather conditions: Severe rainstorms or damaging winds carry in algae spores and debris that can multiply if you do not quickly terminate them. Extreme weathers also cause major water level change.
  • At Night: You will notice that “they need to be used after the sun has gone down” is written on the pack of chlorine (granular oxidizer) and other chemicals used for shocking. Because chlorine is unstable when exposed to the sun. The pool shock may not be effective if done when the sun is up. Shocking your pool at night will prevent wastage and make sure that the chlorine is stable.
  • Before you cover it up for the winter: Covering the pool prevents debris from falling into it. When you are about to cover your pool, there could be algae or other matter that could be on it, that may multiply over the period. So, it is advisable to shock the pool before covering it, for winter or any other purpose.
  • Before you first use your pool after being left unused for a long time: It is not advisable to start using the pool immediately after the cover is removed even if you shocked it before covering. Your pool will need to be shocked after the cover is removed before people can start jumping into the pool. Germs may have multiplied over the coverage period and who knows what may be beneath the pool.
  • Anytime you notice algae growth: It does not matter the number of times you shock your pool monthly, algae spore will always find their way into your pool. Terminate them immediately you spot them.
  • After pool parties: When you or your children have pool parties, food debris and other contaminants such as sweat, makeup, etc get into the pool. You must quickly get rid of them before they cloud up the pool surface.

You need to shock your pool after these conditions to serve as insurance against contaminants and algae. It’s better to take out these contaminants before they multiply in the pool or make anyone sick.

Different types of pool shocks

Pool shocks vary from each other in terms of chemical and physical properties. Pool shocks are categorized into two based on their chemical properties – chlorine-based and Non-chlorine-based pool shock. Knowing the type of pool shock to use for your pool is very important. Using the wrong pool shock may have a negative effect on your pool. So below is the list of pool shock, their properties, and when they can be used.

  1. Chlorine-based pool Shocks
  • Sodium Dichlor is a stable pool shock. It is protected from the sun because it contains cyanuric acid. It has a strength of 59% and a pH level of 7. Do not use sodium dichlor with calcium. It is not suitable for people living in hard water areas. If you use cyanuric acid in your pool, you will have to avoid this shock; excess cyanuric acid depletes the level of chlorine in pool water.
  • Calcium Hypochlorite (Cal Hypo): It has a pH level of 12. Its strength varies from 65% to 73% depending on the manufacturer. It is not a stable pool shock. Cal Hypo is the most common type of pool shock, It is not suitable for people living in hard water areas. Calcium hardness levels will increase by 12ppm when you add 2 pounds of Cal hypo to the pool.

2. Non-chlorine based pool shock

  • Potassium monopersulfate: It is the most popular non-chlorine pool shock. This is the only pool shock that contains oxygen and potassium salt. It has the same cost as chlorine-based pool shocks. The strength of most non-chlorine shock is 38% – 42%

How to Shock Your Pool

  1. Protect yourself: You should always wear an overall when you want to shock your pool because pool shock bleaches your cloth and is harmful to the skin. The wearing of gloves protects the hand from harm when touching the shocks. You should also wear protective eye wear to protect your eye. You will need to get these wears to protect yourself.
  2. Prepare the chemicals: You must always read the instruction on the pack of the shock before you mix it. Different products of shocks have different concentrations, so you must check before you mix. You will determine how much shock to use based on the size of your pool. For example, some shocks need to be diluted in a 5-gallon bucket of water for a ten thousand liter pool, while some 10-gallon bucket of water for the same size of the pool.
  3. Shock the pool: After preparing the chemical according to the manufacturer’s instructions pour the shock solution into the pool. To circulate it, it Is advisable to pour the solution close to the jets. You can also pour it evenly around the edge.
  4. Allow it for some time: Make sure no one gets in the water after treatment. The pool needs to get rid of the excess chlorine before it is fit for swimming. Leave it for 12 hours or according to the manufacturer’s instruction. You can start swimming immediately if you use Non-chlorine shocks. Heavy shocking will require 24-48 hours for the chlorine level to drop below 7 ppm. But check the package label, to be sure.
  5. Check your pool chemistry: Make sure you test for the pool’s chlorine level, calcium hardness levels, pH, and total alkalinity. Make sure the levels have returned to normal before you allow anyone in. The pH level is very important after every pool shock. You have wasted your time shocking the pool if the pH is above 7.5 or below 7.2.
  6. Run the filtration system: Make sure to run your filtration system after the pool shock. You can run it while waiting for the pool water to get rid of excess chlorine. It is recommended that the filtration system runs for 12 hours also.

How to prevent constant shocking

Educating yourself on how to prevent constant pool shock helps you keep your pool safer, cleaner, and running efficiently with less mess and frustration.

  1. Do not wear street clothes in your pool. You may be in hurry to jump inside your pool with your streetwear but you must draw the line of which wears get into your pool. Swimming in your pool with your street clothes introduces contaminants and fiber into your pool water. The chlorine in pool water can also dye your clothes. Always use the recommended swimsuits in the pool.
  2. Running your pool filter system. Pool filter systems will not work if you decide to switch them off. If you run your pool filter system, you do not need constant pool shock. Depending on the size of your pool, you should run the filter system for at least eight hours daily. Keep your water clearer by making sure all the water passes through the filter.
  3. Do not use automatic pool cleaners. when you have an algae problem don’t always use robotic cleaner. Robotic cleaners do not remove spores and debris but push them beside the pool (through the pool mesh). Although it may be stressful, always use vacuums to remove debris and algae spores.
  4. Always brush your pool. If you use robotic cleaners or vacuum, make sure to brush your pool. Pool brushing makes the pool always look its best. Some of the pool’s hard-to-reach areas to brush are behind ladders, waterline, steps and stairs, corners, and crevices. if it is needed, brush once a week or more often.
  5. Test your pool water weekly. Water testing serves as an indicator of very few water chemistry problems. Testing your pool water weekly detects these problems before they blossom into major disasters. These tests can be carried out using test strips or a liquid test kit. The following should be looked out for while testing salt and total dissolved solids (TDS) level, calcium hardness, cyanuric acid, pH, and alkalinity. The test sample should be taken to your local pool supply store once a month. The supply store will give you a detailed report of these tests.
  6. Leverage on the calcium hardness in your pool water. As with pH, balancing your water’s calcium hardness is essential to a clear, clean, and safe swimming pool. And while you don’t want too much because it’ll cloud the water, a little hardness is a good thing. You can add calcium hardness increaser to keep your calcium hardness at the recommended level of 175 ppm to 225 ppm (200 ppm to 275 ppm for concrete and plaster pools). Add it when you open your pool to get the level where you want it.


Although keeping a clean pool is very good, it requires a lot of work. If you can shock your pool yourself, it would be great. If you will need to get a pool cleaner, as stated earlier, pool shocking cannot be done with carelessness. Getting a pool cleaner may save you the risks.

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