If 24 gpg is max measured hardness then that is the # you use.

"... very little iron..." is hardly a # than can be used in an equation,

Need to know the water conditions... hardness, iron, manganese, copper, chlorine, nitrates, pH, sodium

What is the diameter of the plumbing at the softener loop?
Is the softener loop serving the entire home or just the water heater?

Adjustable hardness dial is giving you hard water. If you're paying for soft water you ought to get soft (0 hardness) water all the time. Most people get used to the feeling after a month or two.

Also need to know the SFR of the plumbing. Using the bathtub as the measuring point, open BOTH the hot and cold water faucets completely open. Place either a 1 or 5 gallon container under the faucet and measure the amount of time it takes to fill the container in seconds.

RO should get softened water. It will still work with hard water but membrane will foul much more quickly and that is costly.

Also chlorine was tested and was estimated less than .5. not sure what scale that is on. assumed parts per million.

And "very little iron"?

If you don't post the #s then no one can help you.

somehow response was not posted- the one before the chlorine comment.

Juat to clarify- 24 grains was number the Culligan guy said he had tested at some point in our area. accurate. Not even sure that was Our water tested at 12 and 19. Okay, if I use the 24 grain number some calculators say 32 and others say 48. But if the average is closer to 17 will it be less efficient? Use more salt? Regenerate more often than needed? Or when the water is coming in at 12 grains will the system be able to adjust?

"... very little iron..."- none showed up in the tested sample, the toilets do not get stained and the outside sprinklers have own meter and the wooden fence and house brick do not have orange stains where the water hits it. BUT I do notice occasionally slight orange stains under the faucet in the sink.

The big box stores have water testing kits, but I have never tried them. Would one of these give me the numbers or do I need to send away samples to a lab? Or can local water softener companies do a more complete test? Neither salesperson did any other test other than hardness, or for number of grains.

The softener loop is directly after the meter. The copper pipe is 3/4 on the house side of the meter, as well as the loop. Then it feeds the bathrooms and the water heater. The flow rate is 12 gpm, a 5 gallon bucket fills in about 25 secs.

I had thought adjusting hardness was a little gimmicky, and figured after 3-6 mos we would be at 100% softener water. Just wondered is simple enough it might be worth a try.

Local water treatment companies can do acceptable testing but remember, they are trying to sell you so their results and motives can be, at least, questionable. See what your municipal water authority can tell you and what test results they can provide. I've told you above what tests you need at minimum.

Without an accurate set of test results for the water conditions at your house no one can speak intelligently regarding the correct sizing of a softener. With accurate test results and correct info regarding water usage there is nothing gimmicky about correctly sizing a softener to achieve soft water (0 hardness) although actually doing it seems to escape so many water treatment sales people.

You have "... very little iron..." and "...none showed up in the tested sample..." yet "...I do notice occasionally slight orange stains under the faucet in the sink" so it would seem that you DO have iron and that must be considered in recommending the correct treatment hardware and correct sizing.

Was the 12gpm flow rate taken at the 6'x3' Jacuzzi tub?

Until you can post the info we need there is nothing more I can do for you.

Yes the flow was from tub.
I ran tests, negative for lead, copper and iron. Chlorine was less than .5.
No bacteria and pH of 7.5. This time I got a hardness of 250 ppm. Which gives me about 14.

My only question about the various numbers is that it varies widely from day to day because of the different wells that the city draws from and maybe demand and time of day.
I could run the tests again in a day and probably get different levels.
The first test was 19 grains at 630pm and next day at 100pm it was 12. Maybe there were traces of lead or iron or chlorine at that time, but not now.
The official water department report lists .802 ppm for copper and 9.5ppb(billion)for lead. Chlorine is 2ppm. Iron and pH are not listed.

I thought the hardness dial was gimmicky but might be worth considering. I know we can adjust to the softer water and would eventually would go full soft water making the hardness dial worthless.

Water conditions in municipal systems can vary due to different water sources and they test at the treatment plant not at your water meter. When that is the case you size for the highest numbers.

So the numbers I should use are the ones I collected? Or go by the water department numbers?
Highest tested hardness here was 19.
And when setting up softener for highest number how does that effect system? Higher salt use and quicker regeneration because system thinks it is softening at high end all the time instead of the actual amount which could be much lower than at peak? I assume there is no way to monitor how much softening system is actually removing.

Depending on which online calculator I use I get either a 32k or 40k softener size.
I use 19 as peak and 100 gallons which according to the water department was the most water we used in a given month. I even added .5ppm for iron.

I find it difficult to believe that your household only used 100 gallons of water in a month when the accepted average across the US is 60 gpd per person.

Either get consistent and accurate test results, or get a pro in there to test for you, or pick whatever numbers you like and take a shot. If you're right you'll never get any hardness leaking through or if you're wrong you will.

None of the online softener calculators reflect real world numbers and to use those calculators you need to plug in numbers and your numbers constantly change... so which numbers are you plugging in to the calculators?

Seems that you're more concerned with salt usage and frequency of regeneration than getting this right so whatever you choose you'll probably lose sleep over it.

For me, I'm tired of typing the same thing over and over and you don't seem to want to learn or listen so good luck.

You said that I should use the peak numbers. I tried the peak numbers to see what size softener I needed. 19grains and 100 gallons per person.
I used 100 -in the calculators- when it asked how many gallons used. That would be for each person. One month we used an average of 100/person per day, usual usage was closer to 80 gals/person per day.
Going w the higher numbers.
The numbers I have are the numbers i have. If I just tested once and never went to the water department website I wouldnt have more than one set. What can I do if the water isnt consistent?
I am just trying to figure out why it makes sense to use peak instead of average and with my water fluctuating how will i ever know what peak is unless I test daily at different times of the day?

You use peak instead of average so the water is properly treated at the worst water conditions. Had you contacted your water authority FIRST they would have been able to give you their highest system wide numbers which would be your worst water condition numbers and we would use them.

Do you buy tires for a truck based on the truck's empty weight or the truck's GVWR when it's fully loaded?

You NEVER said that 100 gallons was per person per day... you said "According to water department bills our highest daily usage was 200, generally closer to 160" but you have three people (baby does count) and then you said "100 gallons which according to the water department was the most water we used in a given month". So what do the numbers mean and how do you expect people to help when you keep changing the parameters?

I do HOW questions not WHY questions... if WHY is so important then you have a lot of learning to do. While you're learning do you want treated water or are you going to wait till you learn why? FYI, there are lots of water treatment people who don't know HOW or WHY and that's why so many people have incorrectly sized softeners.

With accurate numbers I could tell you the correct size softener you need and how to program it for efficiency. Without accurate numbers my guess is as good as yours so
let us know what you decide to do for water treatment and how it works out so we can learn from your experience.

If I can start over. It seems that we are right on bubble between 32k and 40k, and there are downsides to oversizing and undersizing. Maybe all that can be fixed with automatically regenerating at set times, but that seems to negate the advantage of metered systems.
Currently there are 2 people. My first problem is whether it would be worthwhile to size for now and have to spend more later to upgrade if and when changes happen, OR size assuming that usage might go up within a couple years. The one that was here was 20k and they had 4 people. Either drastically undersized or water changed over 20 years as people moved into the area and more wells were needed.

I had thought that it was better to get numbers at house vs at source.
"Without an accurate set of test results for the water conditions at your house no one can speak intelligently regarding the correct sizing of a softener"
I posted both water department numbers and what I tested it at.
I keep changing numbers because I keep getting different numbers. I thought average would be good because over 6-8 days between regeneration or even a 24 hour window the system would be able to handle the fluctuations. I understand that at certain times of the day a few grains of hardness might not be completely softened. But might be working most efficiently for the majority of the time.
It seems like the city is very effective at removing
iron and nitrates. Trace amounts occasionally. If that. Low levels of Manganese, copper, sodium .
The water has a balanced(7-7.5) pH. The city must add some (.5 ppm) chlorine. The city just can't control the hardness. That ranges from 12-19.
And looking into past water usage we typically average about 170 gallons per day. I am not sure what happened when the water peaked at 200 gallons per day. Likely that we had party and had extra people in house and during same month we were painting house and used more water to rinse brushes and rollers. Should I plan system around 200 gallons per day when we might not use that amount of water again for another 18 months or ever?

Yes I was not clear about the 100 gallons per person per day. I was going back between the 200 per day maximum from the water department for the household and the 100 I used in the calculator for gallons per person, along with the 19 grains. Even at the peak water usage and highest hardness and using 1 ppm of iron I find that no clear answer. And maybe it just comes down to regeneration period.
Which goes back to original problem. is it better to use smaller system and regenerate more often based on metered amount used or use larger system and go longer between regenerations and set time to 7,8 or 9 days?

Iron .0095 ppm
hardness 19
persons 2
gallons used 85/ person
sodium 33 ppm
lead 0
manganese 0
copper .8 ppm
pH 7.5
chlorine 2 ppm

It's better to use a properly sized and setup softener. Use metered softener. Do not use a timer based softener.
Plan the system for 60 gallons per person per day.

That makes more sense to me. If I plan for peak numbers I'll be buying system that ends up being underutilized in off chance that once or twice a year I use more water than average. Better to plan for average and allow the system to monitor usage and adjust to low and high numbers.