Adding the right amount of liquid chlorine to a pool is crucial for it to work, and that is what we’ll be looking into in this short guide.
What is Liquid Chlorine?
As the name suggests, liquid chlorine is essentially a solution of water mixed with pure chlorine.
Chemically known as sodium hypochlorite, it is the same thing as laundry bleach but with a double concentration of chlorine. The bleach you use to wash your clothes contains about 6% chlorine, liquid chlorine contains between 10-12% chlorine by volume.
The job of chlorine in your pool is to eliminate any microorganisms like bacteria and algae. Many people prefer trichlor or dichlor chlorine tablets for this sanitization, which have a higher concentration of chlorine in a stabilized form. Liquid chlorine is the unstabilized form of chlorine and has advantages over chlorine tablets.
When to add Liquid Chlorine to your pool?
The best time to add liquid chlorine to the pool is when the chlorine levels in the water are below normal levels. Depending upon the different factors that affect the water chemistry, this can be biweekly, weekly, or just once every couple of weeks.
Pool water should have a pH between 7.2 and 7.8 and a free chlorine between 2-5 ppm (parts per million). If the free chlorine levels in your pool water dip below 2 ppm, it is time to add some liquid chlorine.
Testing your pool water every day is the best route to staying informed and maintaining the perfect water chemistry. Since using pool test kits is time-consuming, you can use our Sutro Pool Monitoring System. This battery-powered device floats in your pool water and sends readings of pH and free chlorine levels to the mobile app three times a day.
You will also need to add liquid chlorine in pool-shock quantities if there’s an onset of algae in your pool. The presence of algae can be easily identified by cloudy pool water and sliminess on the pool walls.
How much Liquid Chlorine should you add?
Adding the right amount of liquid chlorine to your pool water is crucial. You can use a simple formula to measure the exact quantity you need to add.
Before you begin, you must know the volume of your pool, the current water chemistry, and the concentration of liquid chlorine you will use.
Most pool owners will know the exact volume of their pool, but in case you are not aware of it, check out our pool volume calculator for an approximate measurement.
The chlorine concentration is mentioned on the packaging of liquid chlorine and tells us the percentage of chlorine mixed with water. It usually falls between 10-12.5%, with 12.5% being the most common value.
Adding 0.13 ounces of pure chlorine to 1,000 gallons of water will raise the chlorine levels by 1 ppm. These numbers are the basis for all your calculations for adding liquid chlorine to pool water.
Let’s say you have a pool with a volume of 10,000 gallons of water and liquid chlorine with a 12.5% concentration. So eight ounces of this liquid chlorine will equal one ounce of pure chlorine (12.5% times eight equals 100%).
To raise the free chlorine levels of such a pool from 1 ppm to 2 ppm, you’ll need to add 1.3 ounces of pure chlorine. Taking into account the concentration of our liquid chlorine solution (12.5%), you need 10.4 ounces (eight times 1.3) to raise the level of chlorine in a 10,000-gallon pool by 1 ppm.
Here’s the formula for a 12.5% concentration liquid chlorine solution:
Weight of liquid chlorine in ounces = (Desired ppm - Current ppm) x (pool volume / 1,000) x 0.13 x 8
Do you want to know how much chlorine you need to add without calculating?
Our product the Sutro does exactly that, it measures the chlorine three times a day (it also measures pH, total alkalinity and the water temperature).
The best thing is it tells you also how much chlorine (pH and alkalinity) you need to add.
The Sutro Pool Monitor System works with over 99% of the brands of the market, so you can continue to use the chemical products you have.
Stop spending time on testing and calculating how much chlorine your pool needs and get the Sutro instead.
How do you add Liquid Chlorine to your pool?
Check the water chemistry (pH and free chlorine) and prepare the amount of liquid chlorine to be added to the pool water. If the pH levels are out of balance, consider adjusting them before adding chlorine.
You can add liquid chlorine to your pool via a chlorinator or directly to the water from the jug. While the mechanical chlorinator makes this process automatic, you should pour it from an arms distance between the jug and the water, and in the deepest part of the pool. It is preferable to have the pool pump running while you add liquid chlorine to ensure proper mixup.
Another crucial aspect is the time when you add liquid chlorine to your pool. The best is to do this while sunset, at night or before sunrise so the pool is unused for at least eight hours.
Additionally, sunlight depletes free chlorine fast, and since liquid chlorine is unstabilized chlorine, it is even more prone to UV rays from the sun, so the best time to do so is when it's dark.
When can you enter the pool again after adding Liquid Chlorine?
If you have added liquid chlorine only to balance the water chemistry, you can use the pool after four to five hours or until the water balance gets restored. If you have used it for a pool shock, it is best to wait for at least 24 hours before entering the pool. Additionally, it is a good idea to always check the water chemistry before entering the pool.
What else should you know about Liquid Chlorine?
Liquid chlorine is comparatively a lot easier to use than chlorine tablets. While other pool chemicals have to be mixed and prepared in the right proportions, liquid chlorine comes premixed and ready to add. All you have to do is to calculate the appropriate amount for your pool (or just use the Sutro) and add it to the pool. It is also a lot cheaper than dichlor and trichlor tablets.
However, liquid chlorine has a few drawbacks over granular chlorine and tablets. Due to its low concentrations, it may take many bottles/jugs of liquid chlorine, even for a minor adjustment in chlorine levels. Additionally, it has a short shelf life and quickly loses its potency over a few weeks (especially in hot climates). Both these factors combined make liquid chlorine difficult to transport and store.
Liquid chlorine is non-scaling and does not leave any residue. Plus, since it does not come combined with CYA, you don’t have to worry about increasing the CYA levels in the pool water. Also, remember that liquid chlorine is highly alkaline and has a pH close to 13. So the pH of your pool water may increase for some time, but it will soon return to normal levels.
Liquid chlorine is a cost-effective and easy-to-use alternative to chlorine tablets and powder. You can add it directly to the pool water, and the amount is easy to calculate. However, it also has a shorter shelf life and requires some patience.