Increased hardness pass-through with lower salt settings?

Discussion in 'Water Softener Forum, problems, installation and r' started by catman, Mar 14, 2013.

  1. catman

    catman New Member

    Messages:
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    Location:
    SE PA
    I was adjusting my softener today and setting it down to 4.5lbs salt per cubic foot to yield 17,000 grains capcity (1cuft resin). I was online verifying that 4.5lbs is indeed 17,000 grains as most charts stop at 6lbs salt and I found these comments below that state the lower salt settings yield lower grain capacity (which we know), but also greater hardness into the water system, which is something I have never heard before.

    I assumed that what is on the resin stays on the resin and the using lower salt just removes fewer total cations and therefore reduces its capcity before the next regeneration. Is there truth to this? I am wondering if at the low setting I have (4.5lbs salt) I would be getting mildly harder water than using a higher salt setting.

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    When setting up your water softener you usually have a choice of salt usage settings. The higher the salt setting the more "powerful" the force is on the water softener resin and therefore it will more completely remove the hard minerals from the water. As you lower the salt setting the force decreases and starts to let more hard minerals pass though the softener.
    Softeners are usually assumed to be set at 15 lbs per cubic foot (ft3). At that setting, your softener will deliver the softest water (<1 p.p.m.). As you lower the salt setting the amount of hardness that can pass though the softener will be higher (2-3 grains) but the amount of gallons water you can run through per pound of salt used to regenerate the softener will increase.

    For instance if we take water with 10 grains of hardness and run it thought a 15 lb regenerated 30K softener, we could expect to get about 3000 gallon or about 200 gallons per pound of salt. If we take the same softener and regenerate it with 6 pounds of salt, then we would make 2000 gallons of slightly hard water or about 333 gallons per pound of salt. For residential application having up to 4 grains of hardness would still be considered soft water. The only time you would use a 15 pound salt setting is for applications requiring less then 1 p.p.m. (1 grain - 17.1 p.p.m.)

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  2. ditttohead

    ditttohead Water systems designer, R&D

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    It is absolutely true that lower salt settings will produce harder water. Only one person on this forum will even attempt to argue the point, but every guy who does field service and uses high quality test kits sees this and understands it. It is particularly important to understand for commercial reasons. For residential applications, salt settings as low as 4 pounds can produce acceptable results. If the water is not as soft as a customer desires, increasing the salt dosage will usually correct the problem. Here is a great article written by Chubb. He is one of the smartest guys in the industry and this article shows the difference between almost soft, and truly soft water in a simple to understand way. I have also posted the hardness leakage charts on this site many times. Here is another article that goes through some of the specifics of water softener resin. These articles are just that, written by people with considerable knowledge. it does not mean everything they write is exactly correct, but they offer excellent information on the topic. http://www.garreltswater.com/documents/Water-Softener-Resin.pdf

    From a personal standpoint, I regenerate my system with 8 pounds of salt per Cu. Ft. because I prefer the softer water it provides. It is noticable.

    Hope this helps.
  3. catman

    catman New Member

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    18
    Location:
    SE PA
    Thanks Dittohead,
    The unit came set at 8lbs per cuft, and I have been pleased with the water quality, so more than likely I'll set it back at 8lbs. It's going to regenerate once per week reagrdless of the salt setting because it is slightly oversized for our needs, plus has a carbon filter in the top half (sort of like a Hague unit). They suggested I set it for once a week to keep everything working at its best. So really it was just a matter of how much salt I want to use each time.
  4. Mikey

    Mikey Aspiring Old Fart, EE, computer & networking geek

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    Missing link?
    Interesting article. He says, "...standard softening resin has published maximum capacity up to 40,000 grains." Is that per cubic foot?
  5. ditttohead

    ditttohead Water systems designer, R&D

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    Location:
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    32,000 regenerated, 40,000 is probably the raw, unused resin. A softener will never have the same capacity after it is used the first time. I usually calculate it closer to 35,000 grains fresh out of the bag. This calculation usually only applies to disposable filter cartridges. I have never tried to see how much of that maximum capacity I could get back in our test facility, but I do know it would waste too much salt and the hardness leakage calculations gets to below 2 ppm with as little as 12-16 pounds of salt, anything lower is typically not needed.

    http://www.wcponline.com/pdf/1203Michaud.pdf

    Does this link work? Chubb is one of the most respected guys in this industry and has forgotten more about water than i will probably ever know.
  6. Mikey

    Mikey Aspiring Old Fart, EE, computer & networking geek

    Messages:
    2,714
    Location:
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    That link worked; thanks. I had read this back in December, so you may have posted it then.
  7. Gary Slusser

    Gary Slusser That's all folks!

    Although right out of the bag and run to total bed exhaustion, meaning it won't remove any more hardness, after the first use, your new resin, usually 8% cross linked, has an operational maximum 30K of capacity per cuft. You say you need 17K for an average of once per week regeneration; 30K-17K leaves 13K of capacity in the tank. From the link to what Chubb says about residential softeners; "WQA has long preached that only water of less than one grain per gallon (< 1 gpg or < 17.1 ppm as CaCO3) qualifies as soft water, and only those treatment devices that produce soft water can be called softeners.". Your 4.5 lbs will get you the 17K and will get your water down to 0 gpg (or less than 17.1 mg/l or ppm) hardness which means your softener is working as it should. The only way that wouldn't happen is if your hardness , iron, manganese etc. would increase but, your metered control valve is regenerating based on gallons of water used and would regenerate on average every 7 days, or on the number of days of calender override but... eventually the extra capacity used to remove the increased 'hardness' would use up some or all of the 13K and you'd start getting hardness through the softener. Then you increase the salt dose lbs to a max of 15 lbs/cuft and do 2 manual regenerations, one after the other with no water use during or between them, to get back to the operational 30K and you redo the hardness calculation for the increased hardness and come up with the new K of capacity and salt dose lbs it requires. You'd do the same if you eventually had more or fewer people in the household than you have now. In some commercial/industrial applications you use mg/l or ppm of hardness instead of gpg because the softener may have to allow no more than say 3 ppm or mg/l of hardness in the softened water or a manufacturing process/product would fail to be acceptable. I say if a residential softener produces 0 gpg hardness the softener is working fine, which is what ditto goes on about every chance he gets; like above. BTW, every softener I sold included that same soap test that Chubb wrote the article about. For salt efficiency you divide the K of capacity by the lbs of salt used. 17,000/ 4.5 = 3777 grains/lb (are you sure will regenerate 17K in a 1.0 cuft softener?). 30,000/ 15 = 2000 grains/lb. 17,000/ 8 = 2125. and the things that web site said about using gallons per lb are wrong. The K of capacity dictates the gallons on the meter.
  8. catman

    catman New Member

    Messages:
    18
    Location:
    SE PA
    Thank you Gary,
    I think there are two different concepts here:

    1) The capacity of the resin
    2) The "leakage" of the resin based on salt dosage

    By capacity calculations, everything you state is correct and this is how I bought the system. I intended to slightly oversize the system and use lower salt and then over time as needed, increase the salt to account for reduced effiicency of the resin. Eventually the resin would need replaced of course, but not for a while.

    While reducing the salt dosage and looking online, I discovered the concept of "leakage". I have not searched for Ditto's charts yet, but what I am gathering is that at lower salt dosages, not only is there reduced removal of hardness in terms of total grains, but also a reduced capacity of "complete" removal from any given resin bead. What I am taking this to mean is that even if I have a 30k grain capacity and I use up 13K of that one week and regenerate with 4.5lbs salt to restore a theoretical 17K worth of grain capacity, there will be some hardness left on the beads that can be "rinsed through" somehow and enter the water system.

    On paper I would have 0 grains, but in practice I would actually have 1,2, maybe even 3 grains hardness in the actual usable water, (at least over time if not during the first few uses since I have extra capcity to start) . I have not seen specific data on this in the articles yet, and I wonder if Chubb knows how to use a pipette as those test tubes do not look uniform in volume to me, but regardless I think the concept of leakage makes plausible sense and so for now, I have gone back to 8lbs/cuft of salt. I do not have time at the moment to take varying samples and get them tested for verification.

    Thanks to everyone for their expertise!
  9. Gary Slusser

    Gary Slusser That's all folks!

    You are making a couple of incorrect assumptions but 8 lbs is fine if you want less salt efficiency.
  10. catman

    catman New Member

    Messages:
    18
    Location:
    SE PA
    I am not trying to make any assumptions, I am trying to sum up what I think I am being told by everyone. Please let me know your thoughts. I have no proof of anything right now other than what I can gleam from here and the manufacturer. Even the person there had to look in some book and on a demo unit to figure out how to change the salt settings, so clearly the technical stuff behinds the scenes lies with a handful of people in the background and I have no access to them.
  11. Gary Slusser

    Gary Slusser That's all folks!

    Do you expect 0 grains per gallon or 0 ppm or mg/l? Residential softeners work om gpg, and if you get a test result for gpg showing 0 gpg, the water is considered soft and the softener is working as designed.

    If you want 0 ppm or mg/l you should go for counter current (upflow brining) and possibly fine mesh resin and use a lower salt efficiency in a packed bed softener, meaning no freeboard or expansion of the resin bed. IMO that would be serious overkill for residential softening needs.

    Sad to say it but... the industry is full of people that sell softeners and don't know what they are doing and as you have seen, that is not limited to internet dealers. I think that manual showed how to set the lbs of salt.
  12. lifespeed

    lifespeed Member

    Messages:
    321
    Location:
    California
    I noticed an improvement in water quality when I increased salting from 6 lbs/cu ft to 8 lbs/cu ft. This is both subjective in the shower, and using a Hach 5B test kit. Both settings produced below 1 GPG, it is just a matter of how much below. I just have cheap generic resin, had I insisted on SST-60 I suspect 6 lbs/ft would have produced better results.
  13. ditttohead

    ditttohead Water systems designer, R&D

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    Location:
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    My wife notices the difference as well, as does my hach PPM test kit. The difference can be as much 3-5 ppm especially near the end of the systems capacity, or 1/3 of a gpg. The SST resin produces slightly higher quality at the end of the run but we usually only recommend it when extremely soft water is required. Even then, we prefer to use standard resin and use a polishing system design. For residential applications, 8 pounds per cu. ft. seems to be the real sweet spot for maintaining good efficiency, and high quality.
  14. Gary Slusser

    Gary Slusser That's all folks!

    For those that have not had a softener before or had one that wasn't providing soft water, you should test the hot water for hardness and compare it to the cold hardness. Many times the hot will be harder until any hard water scale is cleaned out of the water heater tank.

    As to a few ppm more or less hardness, the vast majority of both men and women will not notice a difference in the feel of their water. Plus the fact that a couple more ppm of hardness can stop the "slippery" "slimy" feeling many people don't like.
  15. ditttohead

    ditttohead Water systems designer, R&D

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    Location:
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    lol, just read that.

    "Most people wont notice a difference in the feel of the water, but it will feel different???
  16. Gary Slusser

    Gary Slusser That's all folks!

    You said you don't feel a difference but your wife does, and this is what I said; "As to a few ppm more or less hardness, the vast majority of both men and women will not notice a difference in the feel of their water".

    I didn't say anything about me.
  17. catman

    catman New Member

    Messages:
    18
    Location:
    SE PA
    I got it, thanks! I set the unit down to 6lbs/cuft and my wife said something to me about it, not so much a complaint, but she noticed the water was a little different. I noticed a very mild difference myself. I would not say it was earth shattering or even problematic. If i let it go I am sure we would forget about it and be more than happy with the water, but I decided to set it back at 8lbs and leave it there. 3 bags of salt per year is not a big enough deal to bother with, I would rather my wife be happy. The "slippery" feeling is a bit different between 6lbs and 8lbs and I agree that if someone does not like it, 6lbs would be a better choice, it seemed to just cut it down a hair.
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