We are often asked which type of softener salt to use for our water softener systems. There are a few different types which we will address here. Also, people want to know how much salt to put into the tank and how long it will last.
For the type of salt to use, we generally refer to the manufacturer’s recommendation of “pellet-style salt”. This is what is printed in most of the service manuals for these softener systems. However, we have discovered that these pellets do not always perform properly in tropical climates. The pellets tend to melt and form a salt-bridge or dome at the bottom of the brine tank. Rock salt seems to be the answer to this problem. It would also be a good idea to consider block salt when the softener is located in one of these hot/humid locations.
The typical was softener media resin requires brine to exchange the hardness ions attached to the media beads. The hardness ions are released from the media beads when rinsed with brine. Both the brine and released calcium/lime are then rinsed down the drain by the softener’s control valve.
Brine is simply salt saturated water. Water will dissolve salt that it comes into contact with until it is saturated and becomes brine. This is why the salt level in your softener’s brine tank should always remain above the water line. Following this requirement ensures that the water in the bottom of the brine tank is always saturated with salt. If the level of the salt pellets or block sink below the level of the brine tank’s water line, the solution may be too weak to perform a proper and efficient regeneration of the softener’s resin media.
Which brings us to the next subject, how much salt do you use? As stated above, you should put into your softener’s brine tank enough salt to bring the salt level up above the top of the water. This is the minimum amount. Beyond that, you can fill, or even over fill the brine tank with salt. It does not matter, just so long as the minimum amount is in that tank. So for people that can spare the floor space and do not want to hassle with lugging around 40-pound bags of salt too often, a larger brine tank is the way to go. You can choose various brine tank sizes on the same page that you would order your softener from as an option. By default, some of our larger softener systems already come with a large brine tank.
For small to medium residential systems we select a 15x17x36 rectangular brine tank, but you can also select an 18×30 or 18×40 round brine tank. Some of the larger softeners also have a 24×41 round commercial brine tank available. Commercial brine tanks do not come with a brine grid as they are not necessary
In so far as how long a 40-pound bag of salt will last in your softener, there are several variables to consider which make it very difficult to predict. First is the amount of hardness or compensated hardness in your water. Generally speaking, 15 pounds of brine is required for every cubic foot of softener media to regenerate. This amount can vary a lot. For example, we currently have several softener systems that are serviced by us in our local area which are operating on 20 grains per gallon of hardness with no iron present. So it would seem that a 32,000 grain softener (1-cu/ft capacity) would require 15 pounds of brine solution for each regeneration. But this is not the case. Usually 8 to 12 pounds will do. The water pressure, temperature and flow rate also become factors. There are also a few of the newer control valves out there that are more “salt stingy” than some of the older mechanical ones.
Which softener salt do you use? Unless you are in the tropical climate mentioned above, use what the manufacturer recommends, which is softener salt pellets. Which brand? The least expensive brand in your area. We are fortunate here in Michigan. Softener salt is reasonably price, but I have heard of other locations in the US where the cost of a 40-pound bag of salt is as much at $4 higher than normal. We do not carry softener salt on our web site. It would not make much sense to distribute such a heavy item. Once the cost of shipping is added to a bag or more of salt, it would become more costly than even the higher priced locations.
So how much salt is there left in the water after the softener regenerates? How much sodium will you be consuming when using a water softener? The Mayo Clinic has the answer to that one. Basically, the answer is very little. But if you want to completely eliminate sodium produced by softened water completely, then potassium chloride is the choice for you. Potassium chloride costs about $1 more per 40-pound bag here in Michigan, but it is just as effective as salt (sodium chloride) at regenerating your water softener’s media bed. Keep in mind that often times untreated water may already have sodium in it and softening your water with potassium chloride will not reduce that pre-existing amount.