We need chlorine in our swimming pools to disinfect the water and to oxidize the contaminants. Various chlorine compounds are available to the Pool Operator/Owner: liquid chlorine, quick dissolve granular (Dichlor), slow dissolving tablets (Trichlor), just to name a few. We can also generate the chlorine by installing a Salt Water Chlorine Generator (SWG) system.
For these to work, salt (NaCl) must be added to the pool — about 3000 to 3500 ppm (3000 to 3500 pounds of salt per 1,000,000 pounds of water). These devices pass an electrical current through the slightly saline water. This current will split the NaCl (which is one sodium atom (Na) and one chlorine atom (Cl)) molecule — producing the chlorine needed to disinfect and oxidize the pool water. The 40,000 gallon rated devices will generate approximately 1 pound of chlorine for every 24 hours that they are “on” or running.
Most models will have a control to set the percentage of run time. The setting indicates the “on” time (generating chlorine) as a percentage of the main circulation pump’s run time. For example: if the pump runs 8 hours a day, and if the SWG’s control is set to 50%, this means that it will generate chlorine for 4 hours each day. It will take approximately 6 days (24 /4) to produce 1 lb. of chlorine. That’s 10 ppm for a 12,000 gallon pool.
Because the chlorine generator will raise the pH of the pool water a bit, acid will need to be added on a weekly basis. Keeping the pH at 7.6-7.8 and the TA at 60 to 80 ppm is best practice. And the cyanuric acid (chlorine stabilizer) should be kept a little higher — about 70 to 80 ppm.
Some customers really like SWG’s. When operating properly, they do keep the pool water crystal clear. Some people even claim the water “feels” better or it’s “softer” to the skin. I do remind them that just because salt is in the water — this is NOT soft water. The definition of soft water is the absence of calcium, NOT the presence of salt. All pool water will have calcium in it!
Again, we wish to thank PoolCorp for hosting our CPO class this past Thursday and Friday, February 23-24 at SCP Riverside. And a special thanks to Kyle for helping us carry our equipment and supplies up stairs!
Nice post. I retweeted it on my twitter feed, TechPoolRepair, and on my Facebook page, user name: Technical Pool Repair.
Thanks Clint — we’ll keep in touch.
Steve, thanks for the great training. I do maintain daily a 50,000 gal Pool and 600 gal jacuzzi, both using SWG. I get great compliments from guests at the hotel on how crystal-clear the water is. Some have said at night, there is no water in the pool!
Thanks for the article Steve. Salt Water Chlorination has many benefits and for sure one of them is the feel of the water. No burning eyes, funny colored hair, it does not smell like a chemical pond and you don’t want to immediately rinse off after a swim. There is another method of salt chlorination that requires no salt in the pool. It helps eliminate many of the complaints about salt water pools and their problems. The system is called The Chlorine Genie, and is a valuable addition to options for salt water chlorination. Just wanted to share that.
thanks for the great training. I do maintain daily a 50,000 gal Pool and 600 gal jacuzzi, both using SWG. I get great compliments from guests at the hotel on how crystal-clear the water is.