Bleach is one of the ways some swimming pool owners choose to maintain there swimming pool chlorine levels throughout the swimming season. I have used this method in the past as well and if you follow the proper steps, it is one of the easiest ways to keep your pool sparkling clean.
When you are using bleach as your swimming pools chlorine, you will need to test your swimming pools water chlorine levels daily. Once you determine the current chlorine level, you will need to add the appropriate amount of bleach required to bring the chlorine level to about 3 to 5 ppm. You will need to repeat this step daily to replenish the chlorine that burnt off the previous day.
When using bleach as your primary source of chlorination for your pool, testing the chlorine levels daily is very important. The active ingredient in bleach is sodium hypochlorite. This is the same ingredient found in swimming pool chlorine, tablets and what salt chlorinates generate when using the salt method.
When you add bleach to your swimming pool the sodium hypochlorite is raised in your swimming pools water which raises the chlorine levels.
When I was using this method I always tried to maintain a minimum chlorine level of 3 ppm. The amount of chlorine you will lose over the next 24 hours will be based on the current temperature, possible rain showers, and the CYA levels in your pool.
During the hottest of the summer, I would add enough bleach to bring the chlorine levels to about 5 ppm. This is because I would expect to lose about 2 ppm of chlorine before the next days test.
If it was cooler or I was only losing about 1 ppm of chlorine per day, I would try to only add enough bleach to bring my current levels to about 4 ppm.
There are some experimenting required and over a few days, weeks and weather events you will become an expert when using this method.
DPD POWDER CHLORINE TEST
There are a number of ways to test your water chlorine levels including test strips and dropper bottles, however the more accurate and the way I recommend testing it is with a DPD powder test kit.
When you use this testing method, you will be able to get your chlorine level accuracy within .5 or .2 ppm depending on the amount of water used during the test. It is much more difficult to get that accurate of a reading when trying to depend on the human eye to match colors in determining the levels.
STEPS WHEN USING DPD POWDER
- Fill water tube to the 10 ml or 25 ml mark.
- Add 1 scoop of DPD powder to the tube after you have added the water and swirl the water around. The color of water will turn pink if chlorine is present.
- Next using the bottle of DPD Titrating Reagent that was provided with your test kit, add 1 drop to the pink water and then swirl. Repeat this process until the water turns from pink to completely clear while counting how many drops you have added.
- If you added 10 ml of water to your tube, you will multiply the number of drops you added before the water turned clear by .5. This will give you the amount of chlorine that was in your pool. For example, if you added 5 drops to make the pink turn clear the amount of chlorine in your pool is 2.5 ppm. (5 x .5 = 2.5). If you added 25 ml of water to the tube the steps are the same however you would multiply the number of drops added by .2. This will give you an even more accurate reading, however will use more drops. I recommend using the 10 ml method most of the time. This will get you to within .5 ppm of your chlorine levels.
ADD BLEACH TO YOUR POOL
Now that you have determined how much chlorine is in your swimming pool, you can add the bleach needed to bring your levels back to optimum levels.
There are a lot of variables that goes into determining how much bleach you need to add to your swimming pool. You can use this pool calculator website that will ask a few questions and help you determine the amount of bleach needed.
I have also added a table below for the most common pool sizes based on water volume to help you determine the amount of bleach you may need to add.
| Pools Water Volume | Amount Of 6% Bleach Needed To Raise 1 PPM |
|---|---|
| 5,000 Gallons | 10 Ounces |
| 7,500 Gallons | 16 Ounces |
| 10,000 Gallons | 21 Ounces |
| 15,000 Gallons | 31 Ounces |
| 20,000 Gallons | 41 Ounces |
| 25,000 Gallons | 52 Ounces |
For example, if you tested your swimming pools chlorine levels and determined that there was 2 ppm of active chlorine in 15,000 gallon pool and would like to raise it to 4 ppm you can use the chart above. It would take 62 ounces of bleach to raise the level by 2 ppm.
KNOW YOUR CYA LEVELS
When you are using the bleach method in keeping your swimming pool sanitized, knowing your CYA levels are very important as well. The lower you CYA or Cyanuric acid is in your pools water, the faster your chlorine will dissipate.
If you have no CYA in your swimming pool, you may lose all your chlorine fast especially on a warm and sunny day. This will result in your pool becoming less clear and require a lot more bleach and cost you more money.
PERFORM A CYA TEST MONTHLY
A CYA test is very easy to do if you have the proper testing kit which including Cyanuric Acid Reagent. You will also need a tube that has a black dot on the bottom that you can see when water is added to the tube.
- Fill the tube provided with water to the 7 ml line.
- In the same tube add the cyanuric reagant until it reaches the 14 ml line.
- Close the lid and shake the tube well for about 1 minute.
- After shaken, pour the mixed tube into the other tube provided that contains the black dot little by little looking through the top of the tube. Once you can no longer see the black dot stop filling the tube. The current water level will have a number on the side and that is your CYA levels.
Monitoring your CYA levels monthly and your chlorine levels daily is key to maintaining a healthy and clear swimming pool when using bleach as your primary chlorinating method.