http://www.qualitywaterforless.com/v/vspfiles/downloadables/fleck/56sxtins.pdf Here is a PDF with instructions on how to program your system.

You can do what you suggest. However, you have some iron in your water and it will be removed more completely at the higher 8-lb salt dose rate. It is important to remove iron as completely as possible to avoid long-term resin damage. The salt usage rate difference between 6 and 8 lb doses, for you, will amount to about 2 lb of salt per month.

You softener is really oversized for your water usage, which would be fine if you didn't have the iron in your water. With iron in the water, you want to regen every 4 days to mitigate fouling. Your oversized softener means you will have to make a choice between lugging a lot of extra salt and being salt efficient, because you can't do both. Set C at 48 H at 12 BF at 11 Do at 5 You're going to use a lot of salt. Additionally, you need to do some maintenance to slow down iron fouling. The problem with iron-laden water in a softener is that softener resin has a great affinity for iron and does not release it easily. Iron will slowly foul the softener resin from the inside out. Extra measures need to be taken to remove the iron. For this you have several options. The easiest option may be to simply use Iron-Remover salt. Alternatively, you can use Super Iron Out. You may choose to layer this in with your salt. If you choose this option, use 1/4 C per 40 lb bag of salt. Super Iron Out is more effective if used monthly with the following procedure: Ensure you have a strong brine in your brine tank - at least 24 hours since the last regen. Dissolve 1 C Iron Out in cool water and pour it into the brine well inside your brine tank. If you don't have a brine well, for some reason, pour it down the side of the tank rather than through the salt.Place your softener into manual regen and stay right there.When backwash is complete, the softener will move to the brine/slow rinse mode. Pay attention to the way it sounds. After 10 minutes or so the sound will change when there is no more brine to draw. At this point, we want the Iron Out to sit in the softener for an hour. To do that, push the button to advance to the next regen step, then the next until your softener is back in service mode. Do this as quickly as you can. Switch your valves so your softener is bypassed and wait one hour minimum. Place your valves back in service mode and manually start a softener regen. Once the regen is complete you're good to go for another month. A liquid iron removal system such as Res Up can be installed in your brine tank to feed citric acid to the brine to aid with iron removal. My preferred methods are 1 or 4 because they employ phosphoric acid, which is a much safer chemical than those in Super Iron Out (sodium hydrosulfite and sodium metabisulfite). The choice is yours - pick a method and follow it religiously and your softener will give you many years of reliable service. Since your softener is so large, you could go a month between regens if you installed an iron removal system upstream from your softener, dropping your salt usage from 98 to 16 lb of salt per month. A little light reading about iron removal options in case you are interested: Oxidation/Filtration: An oxidizer such as ozone, air, or chlorine may be used to react with the iron and force it to become particulate iron that can then be removed via filtration. This will also remove most sulfur compounds. A typical setup would involve the oxidizing unit, a holding tank, then a media filter. This type of system works quite well, but takes some expertise in sizing - you would want a water treatment pro that you trust to help you with this option. Oxidizing filtration media: This type of treatment consists of a sealed tank filled with one of several media. Water passes through and is oxidized and filtered by the media. Most will remove sulfur compounds as well as iron. These are relatively easy to operate and what I would recommend for the average homeowner. There are several different media that can be used: Manganese greensand: water runs through for treatment. The media must be regenerated with potassium permanganate. Care must be taken with dealing with potassium permanganate as it readily dies organic material, such as your skin, a purple-brown color. Some people are quite comfortable dealing with the chemical; others are not. Synthetic greensand: This is essentially the same as option (1) but consists of a coating of greensand on a silica sand core so does not require as much backwash flow. Service flow rate is 2 - 5 gpm/sqft. Backwash flow rate is 12 gpm/sqft. Birm: This media acts as a catalyst to force oxidation of iron. While it does not need to be regenerated, it does need fairly high dissolved oxygen in the water. If your water does not have adequate dissolved oxygen (and it probably doesn't since it is well water), air injection would be necessary prior to the birm. Additionally, birm requires a minimum pH of 6.8. Service flow rate is 3.5 - 5.0 gpm per sqft. Backwash flow rate is 11 - 20 gpm, depending upon water temperatures and desired bed expansion. Pyrolox: an ore that oxidizes then filters the iron out. It does not need regeneration, but needs to be backwashed (to rinse out the iron) at a high rate. pH range is 6.5 - 9.0. This type of filter works very well, but backwash is critical. Service flow rate is 5 gpm/sqft. Backwash is 25-30 gpm/sqft. Backwash daily. Terminox: Similar to Pyrolox, but a proprietary formula . It does not require as much backwash flow rate and is more resistance to a low pH. The particulars are only available from the company that sells it - this means you have to rely entirely on the vendor for proper sizing. Backwash daily. Filox: Also similar to Pyrolox. pH range 5.0 - 9.0. Backwash flow 12-15 gpm/sqft. Service flow 6 gpm/sqft. It must be backwashed daily. Pro-OX: Essentially the same as the previous three. Requires 12-15 gpm/sqft backwash. As with Terminox, specs are lacking information so you'll have no way of knowing if the unit you get is sized appropriately. Katalox-light: Similar in action to the previous four, but is comprised of zeolite, manganese dioxide and hydrated lime. It should be designed for 6 - 12 gpm/sqft service flow atnd 8 - 10 gpm/sqft backwash. For well water, it's a good option as it requires lower backwash. In all cases, media ought to be replace somewhere between 5 - 10 years. If any vendor tells you their media lasts forever, walk away - they aren't trustworthy.

Just noticed you said it was city water. That usually doesn't have a lot of iron in it because it's chlorinated. How do you know it's 4.4 grains if you haven't tested it? Assuming that level of hardness is correct and no iron, here is the math: 4 people x 65 gal per day = 260 gpd x 4.5 grains per gall = 1170 grains per day x 7 days =8190 grains per week x 14 days = 16380 grains per 2 weeks Typically you want a softener to regen between once a week and no more than every 2 weeks. Also, you should know that water softener capacity is advertised at 15 - 18 pounds of salt per cu ft of resin - which is an insane amount of salt. So, a softener with 1 cu ft of resin is usually advertised as a 30,000 grain softener. The salt per cu ft of resin vs capacity isn't linear - in other words, you could cut back to 6 pounds of salt per cubic foot and 1 cubic foot would provide 20,000 grain capacity. A system with 0.75 cubic ft of resin set at 6 pounds of salt per cubic foot would have a capacity of 15,000 grains and would regen something less than every 2 weeks. Note that this is a pretty small system - because your water is not very hard at all. You may be able to find what you need on Amazon.