Quote Originally Posted by mialynette2003 View Post
Think of it this way, 1 CF of resin will yield 30,000 using 15 lbs of salt. The same CF of resin will yield 20,000 using only 6 lbs of salt. So you would need a 4 CF softener to get 80k using 6 lbs of salt and that doesn't even include a reserve. IMO it is too big,
And that would be roughly 24 lbs of salt per month but, unless I'm recalling the wrong thread, you said 70K was needed for 6-7 days between regenerations. So there would be a reserve because you actually get 80K (from what you said above, 20K per ft and 4 cuft = 80K).

Quote Originally Posted by mialynette2003 View Post
Gary would have you size the unit based on every faucet in the house flowing at the same time. How many times in your lifetime would you have every faucet running at the same time? That means if you have 2 bathrooms both tubs will be running, both toilets, both sinks, the kitchen sink, the dishwasher, the clothes washer, the icemaker and all outside hose bibbs if they go through the softener.
That is not true. Here's a link to my Sizing page, show me where it says what you are claiming I say or do.

Quote Originally Posted by mialynette2003 View Post
Personal, I set my units up to use 8 lbs per CF and don't subtract the reserve. The added 2 lbs are my reserve. I have 5 people living in the house with 15 GPG hardness. Gary would have me install a 2+ CF unit. I have a 1 CF system and don't get hardness unless it runs out of salt.
Since I think you are selling metered control valves, they regenerate based on gallons and the gallons are based on the K of capacity. The reserve is usually one day's worth of gallons. Now if you have a control valve with variable reserve you don't subtract anything.
What you are doing is covering yer butt by dosing at 2 extra lbs per cuft of resin. In this case (the 4 cuft you mentioned) that would add 8 lbs of salt to each regeneration because you're not sizing correctly but...

Based on what you've said about 70K (the max operating K for an "80K" softener is 75K), you aren't getting that 70K with much less than 45 lbs of salt per cuft per regeneration.

BTW, the salt efficiency is 75/45 = 1666.66666 grains per lb. The 80/24 = 3333 grains per lb and that means a substantial salt savings over time plus, fewer regenerations which saves water too if you know how to set the minutes for each cycle position properly, and your control valve allows it.