When it comes to sanitizing your pool water, homeowners now have a more convenient and regulated method available to them. In the past, the only way to add chlorine to a pool was to either use a tablet and let it dissolve though a feeder or to manually pour liquid chlorine into the water. These methods are still the most popular, but Salt Water Chlorinating systems continue to grow in popularity. Yes, saltwater pools still use chlorine. The difference is that they make the chlorine themselves.
Without getting too technical, Salt Water Chlorinators work by using electrolysis to release chlorine gas from the salt in the water. Food-grade salt is added to the pool water to achieve a saturation of approximately 3,200 parts per million. This is about the same amount of salt found in a human tear. The salt water is then passed though a chlorinator cell that is plumbed into the equipment after the heater. The cell is electronically charged and releases the chlorine gas from the salt. The chlorine gas is mixed with the water to create liquid chlorine and is then delivered back to the pool.
A common myth about pools sanitized with Salt Water Chlorinators is that they are no longer using chlorine. The reason for this myth is that many of the issues related to conventional chlorinating methods are no longer present. With conventional chlorinating, it is common for pools to dry swimmers’ skin or have a strong chlorine smell. These issues are caused by Chloramines. When chlorine is added to the water, it only has a set amount of “killing power.” After chlorine kills contaminates in the water, more chlorine is needed to burn the “dead chlorine,” the chloramines, out of the water. When a pool stinks of chlorine or leaves swimmers’ skin overly dry, there is most likely a large amount of chloramines in the water.
With Salt Water Chlorinators, chloramines are less of an issue. Since the systems are constantly producing fresh chlorine, there is always enough free chlorine to kill off the chloramines. For this reason, swimming pools using these systems will have little or no chlorine smell and leave swimmers’ skin much smoother. When set properly, Salt Water Chlorinators are also easier on pool equipment because chlorine levels are kept at a more constant level and there are fewer spikes in chlorine levels. Not having liquid or dry chlorine around the house for the little ones to get into is also a huge plus.
Salt Water Chlorinators are great, but there are a few things you will want to be aware of before you buy one. Many pool stores and builders tend to only bring up the pros of these units. Although the pros outweigh the cons ten-fold, it is still necessary for anyone considering one of these systems to know common problems that can arise and the reason for them so they can avoid unnecessary disappointment with their new investment.
This list will help you recognize some of the most common problems I have seen in my experience when it comes to Salt Water Chlorinators.
1. The pool filter is not running long enough for the unit to create the needed amount of chlorine. Salt water chlorinators can only produce chlorine when the pump is running. They also have a fixed limit on how much chlorine they can produce in a 24-hour period.
2. Conditioner (a.k.a. stabilizer or Cyanuric Acid) acts as sunscreen for your chlorine. The ideal range is 40 - 80 ppm with 100 ppm being the maximum as set by national health code standards. If conditioner levels are too low, the chlorine produced will be burned off by the sun. If the conditioner levels are too high, above 100 ppm, the amount of chlorine needed to keep the pool properly sanitized may be greater than the amount of chlorine the cell can produce. Free Chlorine levels must be kept at 7.5% of the conditioner ppm to keep the pool properly sanitized. For example, a conditioner level of 50 ppm would require a Free Chlorine level of 3.75 ppm, where as a conditioner level of 100 ppm would require a Free Chlorine level of 7.5 ppm.
3. Phosphates present in the water. Phosphates get into the water from many sources (i.e. source water, pool chemicals, dust in the air, leaves and other yard waste, animal waste, etc.) Phosphates act as food for algae. Some will disagree and say they have no effect, but I have seen it in my own pool, and if phosphate levels are too high, your Salt Water Chlorinator will act as though it is not creating chlorine. What then happens is after the chlorinator creates chlorine, the chlorine immediately has to go fight off the algae that is growing, even if not visible. When this happens, your pool cannot catch up and build a reserve of free chlorine in the water.
4. Salt level is too high. When cells start to fail, they often give faulty salt reading or say to add salt. If this is done without double checking the true reading, you can over salt the water. Most systems will not work if the salinity of the water is too high or too low.
5. Heavy use. If all the neighborhood kids are using the pool a few times a week and you are only running your pool for 6 hours a day, you are most likely not creating enough chlorine to keep up with demand.
6. pH is out of balance. When your pH and Alkalinity get out of whack, your chlorine is less effective. pH should be 7.2-7.6. Chlorinating with a Salt Water Chlorinator is similar to chlorinating with liquid chlorine because liquid chlorine has a high pH. One common problem is that homeowners tend to not test their pools pH and Alkalinity weekly. The main reason for this is that too many builders and retailers sell the systems as a “set it and forget it” solution. Most people with salt systems will run their pH from 7.8 - 8.0+ and higher. This is bad for two reasons: 1), the pool is in a scaling mode and calcium in the water will drop out of solution and build up on pool surfaces; and 2), the chlorine is drastically less effective the higher the pH and Total Alkalinity get. It is best to maintain pH between 7.2 - 7.6 and your Total Alkalinity between 80 – 120 ppm.
7. Homeowners expect the system to last forever. The truth is the salt chlorinating cell has a predetermined design life, usually 10,000 operating hours. Because of this, the actual life of the cell will be determined by the individual installation. For instance, 10,000 hours on a pool in Chicago, IL, will be a much longer operational life than 10,000 hours in Phoenix, AZ, after which, the Chlorinating Cell will need to be replaced.
In conclusion, these units may be relatively new to the U.S., but have been very popular for years in Australia. Many hotels and water parks have already converted to saltwater systems. Salt Water Chlorinators are definitely a step forward in the fight to create an easy-to-maintain pool. When used properly and monitored frequently, there is currently no better way on the market for homeowners to chlorinate their pool.
This article was originally published on Sunday, 27 August 2006. It has been updated as needed.