Your water is pretty hard!

So in your calculations you aren't de-rating the softener capacity based on a lower salt usage (something less than 15# per cubic foot). The capacity of the resin is usually given at 15# of salt, but that's typically an unreasonable amount of salt to use.

So if a cf of resin has a capacity of 30k grains @ 15# of salt, it would have a capacity of 25k grains @10#.

If you went with total of 3cf of resin @10# per cf you would have a 75k capacity. I think that's probably where you want to be. You may be able to set the softener to less than 10# of salt in actual usage esp. since you are currently at 2.5 family members.

I would go with the 10% resin and put a cartridge carbon filter on the drinking water to clean it up. If you use a carbon filter before the water softener, you will have to size it to filter ALL of your water - and that gets much more involved.

Although the lead in your water is below the action level of 15 ppb, you could use a cartridge filter like the KX Matrikx PB1 for lead reduction and to clean up a lot of voc's on the drinking water.

Thank you for your input. Yes the water is quite hard, already build up on new sinks and fixtures so I need to start softening rather quickly.

I think that I now understand little better. Esentialy these softeners provide max amount of grains its capable of, but with not a very economical salt usage. So with 3.0 cf resin based on our condition and usage how many days does it come up with to regenerate. For the following, am I calculating it correctly?

4 people x 60gal x 38gpg = 9120

So 75,000 ÷ 9210 = 8.22 days between regeneration

But currently with 3 people

3 x 60gal x 38gpg = 6300

So 75,000 ÷ 6300 = 11.9 days

With that for 3 people I would lower salt dosage to go back to 7 to 8 days? Is there a formula to find that efficient salt usage number?

Regarding carbon filter, what exact complications should I expect for sizing and any pointers how to get started? The reason that I would rather install it before softener is to treat all fixtures and not just drinking water, specificaly to eliminate chlorine absorption through skin.

Salt usage and capacity per cubic foot of resin isn't linear. In other words, it takes a lot more salt per cubic foot of resin to get that last bit of capacity. This is the chart I use.

The complications with whole house carbon filters come from free chlorine vs chloramine. Free chlorine can be filtered out by a standard carbon filter, while chloramine needs a catalytic carbon filter. Chloramine is chlorine combined with ammonia which is replacing chlorine as a disinfectant. Byproducts of disinfection with chlorine include trihalomethanes which is what is driving the move to chloramine as a disinfectant.

To make that point more clear, open up a bottle of bleach... is the smell overpowering and hurts your eyes, etc even in this relatively concentrated form? No.

It's not until the chlorine combines with other molecules that it becomes chloramine and then you really smell it. Swimming pools smell strong because of chlorine mixed with organic materials in the water...(as in pee) not because of chlorine itself.

I know that this will fall of deaf ears, but I think the residential water filtering industry has gone off the deep end. I have no problem with a basic carbon filter to clean up taste and smell of drinking water, not to mention cleaning up some VOC's and such. I think it's a bit much when people are worried about showering in water with small amounts of free chlorine. In terms of actual risk, I think that removing all of the residual disinfectant prior to a resin bed is probably more of a health risk than showering or bathing in water with some free chlorine. Many people raise the issue of bacteria growing in filters / resin beds / even water pitchers after all of the disinfectant has been removed by a carbon filter.

Most of us have spent time in a swimming pool - and Olympic swimmers spend a lot of time in swimming pool. Other than a possible link between absorbing chlorine from the water and being gay, I haven't seen any serious health effects for Olympic swimmers and divers (ok, I am kidding).

Put in your water softener. Put a cartridge carbon filter / KDF 55 filter on your drinking water. If you need to loop in a whole house carbon filter later you can - but I don't think you will need to.

Just a tip, If this is a DIY job, I've been happy with units I've purchased online from ABC Water. I have no connection to them other than being a satisfied customer. They can put together any system you want. They sell them cheaper through Amazon than on their own website.

Yes, your new math is correct.
In general you want to size it to regen in no more than about 14 days. With 3 cf @ 10# per you fit nicely in the window of 7-14 days. You may be able to dial down your salt usage some once it's installed.

Something to know is that you do get into two other issues as you go much below about 8# per CF: You start using more water because of more frequent back washing, and you start seeing more "hardness leakage".

Getting people to design at 10# per cf instead of 15# is a big savings, but going from 8# to say 6# isn't worth the extra trouble in my book.

BTW: Softeners are sold based on 15# per CF for marketing reasons - Which would rather buy - a 37.5k grain capacity unit or a 45k grain capacity unit? Truth is that they are the exact same unit with different salt settings. Instead of looking at the stated capacity - look at the cf of resin and then adjust the capacity based on 10# per cf.

The actual capacity will also depend on the resin used, water temp, chemistry, etc. so know that the numbers we are using are rough estimates.

Thanks again. Now I know to go with 3.0cf resin and I will check out abc water for pricing on their twin tank system. In the description they do not mention "top" basket so I need to contact them.

Regarding whole house carbon filter, it was my wife's request. "Happy wife, happy life", lol. I'm assuming that the issue might be with bacteria growing in softener (and other plumbing) if carbon filter is installed upstream and chlorine is removed. So does it make sense to install whole house filter dowstream from the softener? That way at least the softener is bypassed.

For drinking water I was thinking RO system, but I still need to do some more research: if it makes sense, if so what type, model, size, etc... Are the light commercial RO system better quality in general vs most residential type? If spending $ on it I rader get something that will last, feasable to maintain, and actualy do what is meant to do vs only providing occupant warm and fuzzy feeling that he or she has "the best water".

I understand the "Happy wife, happy life" issue and I'm not going to try to change your mind.

I am going to make the point about focusing on diminishing returns though. We tend to be really bad about evaluating comparative risks.

We swim in chlorinated pools. We eat fast food, we eat processed meats. We smoke and we drink alcohol. We inhale that "new car smell". We take in a huge stew of chemicals daily. I once had a co-worker going off about the chemical residue on apples - and she was a cigarette smoker. The smoking was a far greater threat to her health than the pesticide residue would ever be even if she ate a bushel of apples a day -- smoking was also something she had the most direct control over.

In general, the US has a pretty good quality public water supply / regulatory infrastructure. It's important to keep in mind that dysentery isn't a thing in the US - and for good reason. By comparison, very small amounts of chlorine in your bath water is a first world problem for sure.

Some basic carbon filtering on home drinking water and being aware of lead issues will go a long way to improving that a little more - esp with children. That said, kids and adults consume a lot of stuff that isn't being filtered through a super-pure home water filter. Do you think that restaurants, bottling plants, food processing plants, breweries, school cafeterias, etc are doing anything other than carbon filtering the city tap water - if they are even doing that?

Getting off my soapbox:

You are going to put a back washing carbon filter before the softener. I can't be a big help on the carbon filter - I do know It really will depend on if you are trying to remove chlorine or chloramines. If it's chloramines you are trying to remove it will get more involved. I can't help as far as sizing either.

I also can't provide any input on the RO filter.