Setting Salt Efficiency

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cowdogs

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So I am looking at improving my understanding of the variables involved in controlling a water softener value for salt efficiency. My value is a Clack EE, but my questions probably apply to any softener.

It seems to me 3 things must be managed.
  • How often/soon the softener regenerates. This is controlled by setting the water hardness and softener capacity (in grains) in the valve. Seems simple enough.
  • How much salt is used when the softener regenerates. This is controlled by how much water is added to the brine tank for the next regen? And this setting is in lbs. for my valve? This makes sense as the amount of salt in fully saturated brine is fixed, and valve uses all the brine during the regen.
  • How long the brine is exposed to the resin. Not sure about this one? Brine regen time? Or brine injector size? Is this something you even adjust? Or is is set according to tank size?
I have a 13x54 tank (2.5 cu. ft.) softener. If I want to try setting it for 6/lbs per ft3. so I will set the value to refill with 15 lbs of salt? 2.5 (cu ft) x 6 (lbs/cu ft) ? And this will translate into about 5 gallons of brine per regen? Am I missing anything here so far?

And finally I don't understand why hardness leakage seem to be treated as a "guaranteed to happen" at lower salt settings. At the moment my softener is oversized. I am building an addition to my house that will make my softener right-sized in about a year. In the meantime, it seems that an oversized softener could be run at 6lbs/cu ft without any leakage? Why is this thinking wrong?
 
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Bannerman

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How often/soon the softener regenerates. This is controlled by setting the water hardness and softener capacity (in grains) in the valve. Seems simple enough.
Your assessment is correct except the Capacity to be programmed will not be the resin's total capacity as most people assume.

How much salt is used when the softener regenerates.
The salt amount required is directly proportional to the amount of capacity to be regenerated. While your 2.5 ft3 resin has a maximum total softening capacity of 80K grains, regenerating all of that capacity is highly inefficient @ 50 lbs salt/regeneration (20 lbs/ft3). This translates to a Hardness Reduction Efficiency of 1,600 gr/lb (80,000 gr / 50 lbs) and minimal hardness leakage.

A more efficient salt setting will reduce the usable capacity and will result in lower quality soft water due to hardness leakage, so a compromise will occur.

The usually recommended settings for the best balance of efficiency, capacity and water quality is 8 lbs salt/ft3 which for your 2.5 ft3 softener will equate to 20 lbs salt to regenerate 60,000 gr usable capacity. These settings raise Hardness Reduction Efficiency to 3,000 gr/lb while only allowing 6 ppm hardness to eventually 'leak' through the resin

The 6 lb/ft3 salt amount you are considering, will utilize 15 lbs salt to regenerate 52,500 gr usable capacity, further increasing HRE to 3,500 gr/lb but also increasing hardness leakage to 10 ppm.

For softening resin to be most effective in removing hardness, almost 100% of the capacity would need to be always regenerated and available for use. Resin capacity that is depleted will not be removing hardness so it is taking up space while providing little benefit.

Because hard water enters at the top of the tank, the resin capacity at the top will become depleted faster than the resin further down the tank column, with the least depleted resin located near the tank bottom.

During each backwash cycle, the resin is lifted, expanded and reclassified so much of the most depleted resin granules will be reclassified throughout the tank, with some ending up at the bottom of the tank.

To regenerate capacity, the brine strength needs to be sufficient to saturate the resin to cause ion exchange to occur. When using a low salt setting, there will be less brine volume produced so when the brine is transferred from the brine tank to the media tank, the strongest brine will contact the resin at the top of the tank column where much of the brine's regenerative capacity will be consumed.

As the brine is pushed down through the resin by slow rinse flow, the remaining brine will become weaker as it is further diluted. Depending on the salt setting chosen, the brine may have lost sufficient strength before contacting 40%, 30%, 20%, 10%. of the resin thereby resulting in various amounts of unregenerated resin remaining after each cycle, resulting in the hardness leakage amounts stated at the bottom of the chart below.

How long the brine is exposed to the resin.

The injector chosen will most commonly cause the appropriate quantity of brine to be transferred from the brine tank to the media tank within approx 15 minutes. The Brine Draw/slow rine setting will then be programmed for 60 minutes duration as the remaining 45 minutes slow rinse will push the brine down through the resin bed and will slowly rinse away calcium, magnesium, chloride and any remaining sodium from the resin.

https://terrylove.com/forums/index.php?attachments/resin-chart-jpg.68704/
 
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cowdogs

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Thank you again. A great explanation. So if I understand correctly, the hardness leakage is not fixed, and it will vary. It will be less right after regen, and more as the resin capacity is used. There will also be less leakage when the water use is lower (in GPM) which allows the water to be in contact with the resin for a longer period of time.

So I am going to try setting the capacity at 52,000 grains, and the salt at 15lbs. Could these efficiency settings be harmful to the resin?
 

ditttohead

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Not harmful to the resin. Here is my chart. Fairly simple explanation.
resin chart.jpg
 

cowdogs

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Thanks Ditto. That is the chart I am using, and it is very helpful. My valve came programmed for 8 lbs/ft3. I'm going to run it that way for a month, and then drop it to 6lbs/ft3 and see if my family can tell the difference. I just wanted to verify the only 2 variables in the value I need to modify are the capacity (60K to 52.5K) and the lbs. of salt (20 to 15). The value will take care of the rest.
 

Bannerman

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Unlike water used for suppling a steam boiler or some industrial applications, the amount of hardness in the water is not usually critical for most residential usage.

1 grain per gallon hardness is equal to 17.1 ppm hardness. Soft water whether containing 6 ppm or 10 ppm hardness, will continue to test less than 1 gpg using a Hach 5B, but the water with higher ppm may feel slightly less silky if compared directly.

Any hardness leakage increase resulting from the salt setting will not be immediate, but will slowly increase to that amount after several regeneration cycles.

Since higher salt efficiency will reduce the capacity per regeneration cycle, regeneration will occur more frequently. Because virtually the same quantity of water will be utilized for regeneration regardless of the salt setting, more frequent regenerations will usually result in higher water usage per month/year.
 
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cowdogs

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Other than power to the well pump, my water is free. Salt is pretty cheap too, but there is some time & effort involved in replenishing it. All things being equal I will lean towards using more water and less salt if possible. I am starting at 15 grains of hardness, and the water feels terrible (sticky). We'll see how it goes.
 

water pro

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@ bannerman. what would the result be if using a salt efficiency setting of 12 lbs to regen 36 of 48,000 grains but keeping the capacity setting at 48000 grains (as opposed to 36000)?
 

ditttohead

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If you exceed the capacity you will run into hard water problems. Softeners have definite calculable capacities. We use these numbers as guidelines and we usually have some margin of error calculated in for unknow water conditions and other ions that will take up exchange sites but in general, anything past the actual calculation is likely to result in hard water.
 
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