by Rob Cox, May 30, 2012
Salt Chlorine Generators. Just add salt and all of your pool care maintenance issues disappear! Don't believe the hype - pool salt systems will remove the "drudgery" of having to buy, transport, store and handle chlorine. This also makes your pool more eco-friendly.
But salt pool systems do require some maintenance to keep them operating properly and to prevent having to replace expensive components like the salt cell, flow sensors and control boards.
Pictured above is a salt cell that has severe calcium build-up between the plates, which reduces flow through the salt cell of course, but also severly reduces the electrolysis, and eventually leads to salt cell failure.
Ironically, the salts that you add to the pool are the same salts that will deposit themselves onto your salt cell. The number one cause of this is high pH levels. Adding salt to the pool will raise the pH level in the pool, and the sodium hypochlorite that a saltwater chlorinator produces will also raise pH. Maintaining your pH level on the low-side, around 7.2-7.4, will reduce scale build-up on your salt cell.
High Total Alkalinity levels in your pool can also be a factor. High levels of carbonates can make it difficult to reduce your pH level and also contributes to the scaly stuff that is attracted to the electrically charged metallic plates. Maintain your TA level on the low-side as well, around 80-90 ppm.
High Calcium Hardness levels in a pool will accelerate scale build-up on your salt cell - you probably could have assumed that much. Maintain your calcium hardness levels on the low side, around 180-200ppm.
Run time of your salt chlorinator can also increase scale build-up on your salt cell. The longer the salt system is operating, the more time it has to attract calcium salts. Keeping your salt level up, at the proper level, and using stabilizer or conditioner, to shield the chlorine it produces from the sun, will reduce necessary run-time of your salt system.
Most newer models of salt cells are now equipped with a polarity reversing mode that reverses the charge on the plates and causes the salt build-up to de-bond from the metallic plates. This is a giant leap forward in salt chlorine systems, and will handle most of the routine salt cell maintenance. However, scale build-up can still occur, and even on systems that are "self-cleaning" (like your kitchen oven) - you will still need to do a proper cell cleaning. Just perhaps not so often. In areas of hard water; Arizona comes to mind, polarity reversal may not be able to keep up with the deposits, and may not be able to win the battle.
That will vary, pool to pool. The best advice I can give for this would be to inspect the salt cell closely every few weeks for the first season, to get a sense of your particular scaling patterns. Use a flashlight if needed, to cast a light between the metal plates. If they aren't shiny clean, a cleaning would be in order. In cases where very few deposits are seen during inspection, you should plan on cleaning the salt cell every 3 months of operation. Keeping the salt cell clean is the best warranty against having to replace it prematurely.
Consult your owner's manual for instructions particular to your specific device. The general method is to shut off power and remove the salt cell from the system, hose it out thoroughly with a high pressure water stream and then bathe the cell for 5-10 minutes in a 5:1 solution of water:muriatic acid. You can buy muriatic acid at any Home supply or Hardware store. Straight vinegar can also be used, but muriatic acid may be preferred.
Some brands of salt systems will have end caps that you can purchase, or you can use winterizing plug to block one end of the cell, and then pour the water/acid mix into the cell. You will see bubbling and fizzing as the acid works to dissolve the scale. When the fizzing stops, the cleaning is complete. Immediately afterwards, rinse the salt cell thoroughly to remove the traces of acid. I like to take it over to the pool and dunk the entire cell in the pool and swish around for about 30 seconds.
Do NOT use a screwdriver to manually scrape off the calcium, as you will surely damage the metal plates.
Most salt water chlorinators have a separate flow sensor and some have a separate salt level sensor. These two sensors, if you can locate them, should be removed and gently cleaned with a toothbrush to remove any scale or dirt that has built up. Be careful as you handle these probes, so as not to damage the metallic coating, or any wires leading to and from the sensors.
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