You need enough gravel to just about fill the bottom dome of the tank. If you go with two-2.0 cuft tanks, then about 27# of gravel. Garnet is denser and more expensive. In a softener, where the media is not very dense by comparison you don't get any extra benefit from the garnet, so just get the gravel. Here is the complete list of requirements: High quality American or German made resin. This will provide a tight size distribution for optimal flow within the resin Since you have CITY WATER: 10% crosslinked resin. The oxidizers that city water treatment plants use, such as chlorine or chloramine, are harmful to softener resins. Higher crosslinking will resist chemical attack longer. Top basket. This serves two purposes. It sets up a proper water distribution during normal operation and prevents resin loss during backwash. Gravel underbed. The gravel underbed is there to set up proper flow patterns, improve backwash, keep the bottom basket in place, prevent basket failure, and prevent channeling. Many softener sales companies like to leave this out or sell softeners with a vortex system instead. Vortex systems weigh less than gravel so they cost less to ship. In addition, they are a more expensive item that adds profit for the softener salesperson, but provides no additional benefit to the homeowner . It simply adds another piece of equipment that can break. Fleck or Clack valves. These set the industry standard. Be aware that you will not be able to purchase Clack valves online. This is not a problem if you purchase locally. The valve should regen based on water usage, not time. Noryl bypass. Most softeners are available with either Noryl or stainless bypass valves. Both are good valves, but the noryl tends to be more reliable when not used for long periods of time. Install the softener with a three-valve bypass. This will make it so much easier if you ever need to remove the softener for repairs or wish to take it with you when you move. Use full-port, quarter-turn valves.

Since the cost difference between the two sizes is small, I would go with the larger softener. The size of your home, number of bathrooms, and your indication that you will have a large number of guests at a time make the 2.0 cubic ft softener a better choice. When it is just the two of you, it will go up to 12 days between regenerations, which is fine with your water quality. The following requirements are for an industry standard softener. If you are looking for a non-electronic softener, Kinetico offers the more reliable options at a premium price (and you would need to deal with a local Kinetico rep). Any decent softener vendor should be able to provide the following: High quality American or German made resin. This will provide a tight size distribution for optimal flow within the resin Since you have CITY WATER: 10% crosslinked resin. The oxidizers that city water treatment plants use, such as chlorine or chloramine, are harmful to softener resins. Higher crosslinking will resist chemical attack longer. Top basket. This serves two purposes. It sets up a proper water distribution during normal operation and prevents resin loss during backwash. Gravel underbed. Since you will have a larger residential softener, this is very important. The gravel underbed is there to set up proper flow patterns, improve backwash, keep the bottom basket in place, prevent basket failure, and prevent channeling. Many softener sales companies like to leave this out or sell softeners with a vortex system instead. Vortex systems weigh less than gravel so they cost less to ship. In addition, they are a more expensive item that adds profit for the softener salesperson, but provides no additional benefit to the homeowner . It simply adds another piece of equipment that can break. Fleck or Clack valves. If you choose Fleck, get the 7000sxt. These set the industry standard. Be aware that you will not be able to purchase Clack valves online. This is not a problem if you purchase locally. The valve should regen based on water usage, not time. Noryl bypass. Most softeners are available with either Noryl or stainless bypass valves. Both are good valves, but the noryl tends to be more reliable when not used for long periods of time. Install the softener with a three-valve bypass. This will make it so much easier if you ever need to remove the softener for repairs or wish to take it with you when you move. Use full-port, quarter-turn valves. This post was edited by aliceinwonderland_id on Mon, Mar 31, 14 at 10:31

From what I have read, I think a 24,000 grain is the correct size? I tested the hardness on a strip and it's about 4-5. 5 people x 75 gal x 4.5 hardness x 6 days between regen = 10,125 We do a lot of laundry and have two dishwashers, both are HE machines but still get above average usage, so I used 75 gal per day per person for my calc. Actually with 24k size, it will be more like 15 days between regen. Is there a problem with that many days? From reading Alice's posts, the ideal is 6-7 days between regen. Water pressure is excellent. Also, hubby likes control, so I think the SXT is the option we will use. Electricity at site not a big issue. will make sure to get 10% cross linked resin since Im on city water, top basket and gravel bed. Now just wondering which Fleck series to go with... And whats the benefit of a twin tank? Thank you!

I ended up with a Clack WS1 48K softener, and a backwashing carbon filter with 1.5 cube of carbon and KDF55 media for it's bacteriostatic properties, and because it will help prolong the life of the carbon. Ended up at $2400 total with the install, a little more than I wanted to spend, but not the $3600 of the Kinetico, and I think I have an excellent system. Not only did the Kinetico cost more, but having to go to the one and only dealer for service and the cost of their carbon replacements, etc. just didn't seem like it was worth it. Only regret is I wish I would have read about the Vortex technology ahead of time, I might have done that or gone with the Watts 3 stage that has all this media in one tank, not two and has Vortex. Installer came by and tested the water, no more chlorine/chloramines, and definitely have soft water. Will be interested to see the change once all the hardness is out of the pipes, fixtures, and it's gone through a regeneration or two.