PEP Tech

Ways to Stretch Your Chlorine

Chlorine Level

The one sure thing I learned this last summer is that nothing is for sure. Just months before the summer hit, we were bracing for a trichlor tablet shortage. I was leading the charge saying don't worry there is more than one way to get chlorine to your pool. At that time both cal-hypo and liquid chlorine seemed to be in ready supply. However, incredible worldwide shortages of materials like plastic for containers and wood for pallets were just a couple of the unprecedented conundrums that seemed to hit all at the same time. Salt and caustic soda are two of the prime ingredients that go into liquid chlorine and manufacturers of liquid need these delivered regularly in order to produce fresh liquid chlorine daily. One of the largest suppliers of these needed raw ingredients suddenly shut down and sought legal protection because they could no longer provide to manufacturers. Cal-hypo tablets were also hit due to a shortage of plastic for the buckets. It was a very difficult time for pool pros dealing with equipment shortages and vital chemicals also. Through this period one of the most vital things we learned was different ways to make chlorine go further.

The first thing to determine in getting the most out of the chlorine is knowing the true strength and proper amount to dose. Many times liquid chlorine is over-dosed due to a lack of proper understanding of the true strength. Based on pounds per gallon liquid chlorine actually delivers the highest amount of free available chlorine.

1 gallon 12.5% liquid = 12.5 ppm of free available chlorine (FAC) in 10,000 gallons
1 pound of trichlor tablets 90% = 11 ppm FAC in 10,000 gallons
1 pound of 65% Cal-Hypo = 7 ppm FAC in 10,000 gallons

During hot summer months, a pool may go through 10 pm of chlorine even with cyanuric acid CYA at proper levels of 30 to 50 ppm. 1 gallon of liquid in 10,000 gallons would last more than a week during the summer. The chart below shows the exact amounts in ounces needed for liquid chlorine. You may be wasting liquid by over-dosing.

SManaging the CYA is another way to use less chlorine. At a CYA level of 30 ppm, it will take just 2.25 ppm of residual chlorine to keep the pool free from bacteria and algae. At a CYA level of 100 ppm, it will take 7.5 ppm to keep the pool free from bacteria and algae. A high CYA level is one of the biggest ways that chlorine is wasted.

Managing Total Dissolved Solids TDS- You should be testing for TDS at least three times a year in a residential pool. You should also know what the TDS of the source water is. The reason this is so important is that if the TDS of the pool water is 1500 ppm over the source water, then you are wasting 50% of the chlorine that is being added to the pool.

Borates- Borates are great for helping chlorine to be more effective. With a level of borates in the pool at 50 ppm, you can use half the amount of chlorine that you normally would need. If you run the FAC at 3 ppm you could run it at 1.5 ppm with borates.

Devices such as UV and Ozone are excellent at oxidizing and reducing the formation of combined chlorine and you can run your chlorine at much lower levels with these secondary devices.

Keeping phosphate levels down by regular use of a phosphate remover can also help. Using enzymes and natural-based clarifiers can help remove excess organic materials that can consume chlorine.

Lastly, keeping the filters clean on a regular basis and replacing media and cartridges proactively will reduce the consumption of chlorine. We all learned that shortages come unexpectedly and at the worst of times. Hopefully, we can find ways to conserve what we need to make it through those tough times

Terry Arko
PEP Talk Magazine