With the growing chlorine shortage continuing to raise prices for the foreseeable future, many are wondering why they are dependent on spending so much money on a product every single month. Today we’ll look at pool salt systems and how they work.
Direct electrical current is applied to plate submerged in salt water, which creates the process known as electrolysis. This splits the molecules of sodium chloride (salt), and you end up with pure free chlorine in the water. This free chlorine circulates throughout the pool, it is used and eventually converts back into salt, creating a sustainable process that repeats. That’s not something that just happens in a saltwater pool. Any chlorine pool is the same. If the pool is treated with liquid chlorine or chlorine tabs, or any kind of chlorine, salt is added to the pool. For every gallon of liquid chlorine added, for example, approximately 2 pounds of salt is added & remains in the pool, because all chlorine is made from salt. With the salt system, when the chlorine is done, used up, it converts back to salt as well. By using a saltwater pool, the only difference is that instead of buying chlorine, the pool is producing its own.
Salt Cell: This is installed in the plumbing, on a bypass, after the heater. This cell contains varied numbers of titanium plates coated in an alloy called ruthenium. As the saltwater flows through the cell and across the plates, DC voltage is sent to the cell and free chlorine is created.
Power Supply: This is just to meter out the power to the salt cell. AC power is taken and transformed into DC voltage, which is doled out to the salt cell as needed.
Since the whole process is sustainable, salt is typically only lost by water splashing out of the pool, rainwater dilution, and backwashing. When that happens, eventually some salt will need to be added. Salinity of the water must be verified occasionally to make sure it’s enough for the ECG. How much? That varies by manufacturer but is anywhere from 3000-4500 ppm typically. There are a few systems that require no salt at all in the pool and use a brine tank instead.
The salt cell will need to be cleaned occasionally. Electrolysis attracts calcium from the water, and every few months the cell plates will need to be soaked in a very weak acid solution. Clean too often, or with too harsh of acid solution, and you’re doing more harm than good.
Cost Savings: Chlorine costs are skyrocketing. A pool at Oak Ridge recently spent $60,000 on chlorine to get them through a few months: Oak Ridge pool: Chlorine purchase approved for summer (oakridger.com). Even before the chlorine shortage, electrolytic chlorine generators (ECGs) allow facilities to save anywhere from hundreds to thousands of dollars a month in chlorine costs. Instead of purchasing chlorine, they purchase pool salt, which is much cheaper and doesn’t have to be constantly added.
Preference: People like the feel of saltwater pools on their skin. One of the most common quotes we get is people saying they don’t feel like they must take a shower when they get out of the saltwater pool.