Water Softener Confusion

[MIndy Roo]

We just bought a house are are looking to purchase a softener. Per the city, where we get our water from, the PPM water hardness is ~500. (can this be converted to gpg?) We have two adults and an infant, but would like to get a system that could eventually handle 4 people. We are conservative with our water usage and use approximately 70 gallons TOTAL PER DAY. From what I can tell that puts us at 1.0-1.5 Cubic Feet of resin capacity needed, but to be honest I've confused myself. Any help is appreciated!

 

[Reach4]

Per the city, where we get our water from, the PPM water hardness is ~500. (can this be converted to gpg?)

Divide 500 by 17.1 to give 29.2 GPG. Actually you would want to get your own Hach 5-B test kit. Over 30, and you would test a mix of half test water and half distilled. Then multiply the grains by 2. I would probably start with that.

The hardness may change as the city switches wells.

The Gary Slusser calculator says 3 cuft is the minimum cubic foot size of softener required for your capacity needs, presuming 4 people and 30 GPG.

So a 14 x 65 tank would be good for a single tank softener. You could go to a dual tank and use two smaller tanks that regenerate whenever needed rather than waiting until the middle of the night.

 

[Sponsor]

 

[MIndy Roo]

@Reach4 even with our total daily water usage at 70 gallons (up to maybe 140 with 4 people) we should look at 3cuft?

Thanks so much for your help!

 

[Reach4]

@Reach4 even with our total daily water usage at 70 gallons (up to maybe 140 with 4 people) we should look at 3cuft?

For 140 gallons per day, 2 cubic ft ("64,000 grain") would be a good size. 1.5 cubic ft would be good too with plenty of capacity for now and a little beyond. Once the water use rises to 140 gallons per day, the softener would regenerate more frequently than every 7 days. The reasoning behind the suggested sizing is that each day at 2am (default), the softener compares the remaining capacity to what it expects to need to get through a whole day. Suppose that amount required is 170 gallons. If the softener does not calculate that it has another 170 gallons of softening left, it regenerates at that time. So on average, you might leave about 1/2 day of softening unused. 1/2 day out of 7 is considered to be OK, and 1/2 day out of 6 is not what you normally want due to a little extra salt usage. You have to draw the line somewhere, although it is somewhat arbitrary. If there were 6 days in a week, maybe the line would be commonly drawn at 6 days. Is your concern of not going bigger than needed is initial cost, space, or both. Bigger causes you to use less salt per grain of softening. Usually you want to use 6 or 8 pounds of salt for each cubic ft of resin. This gives good economy and softening.

For city water, you are better off getting the 10% crosslinked resin. It is more chlorine-resistant.

 

[Bannerman]

Proper softener sizing also takes into account the flow rate needed per minute. This is why the number and types of fixtures are typically asked. A softener with a larger quantity of resin will support a higher soft water flow rate vs a smaller amount of resin. If the flow rate for the resin quantity is exceeded, then some hardness can leak through the softener.

Many of the online softener sizing calculators provide a minimum size recommendation based on 60 gallons or 75 gallons per person per day. While your consumption is currently well below the 60 gal/pp average, will it always remain that way?

It is often beneficial to obtain a slightly larger softener than you expect you need particularly as you are using a chlorinated water source. For water efficiency, it is usually desirable to regenerate not more often than 1X per week but there is no harm if the softener regeneration frequency is as little as once every 30 days.

While the softener's total capacity is usually stated on sales literature, the softener is typically programmed to utilize only a portion of the total capacity before regeneration, thereby resulting in higher salt efficiency and lower salt consumption to deliver all the soft water required.

 

[MIndy Roo]

We have two toilets, two showers, three sinks in the home, a dishwasher, and washing machine. I don't see our water usage changing too much, as we live in drought ridden southern California, where water conservation is key. We were looking into a fleck 5600sxt with 64,000 grain round tank, now to decide where to purchase it from (DIY install by a pretty handy husband).

 

[Bannerman]

We were looking into a fleck 5600sxt with 64,000 grain

That system would contain 2 cuft of softening resin.

That size softener will support up to ~13 gpm which should be plenty based on your current consumption rate, plumbing configuration and occupancy.

For efficient salt utilization, you could use as little as 12 lbs of salt per regeneration cycle, but the usable capacity provided at that setting would then be 40,000 grains (40K).

At 70 gallons/day X 30 gpg = 2,100 grains/day required.

40K usable capacity divided by 2,100 grains/day = ~19 days expected between regeneration cycles at your current water consumption rate. Regeneration will be more frequent if you utilize more water. That size softener will work great for you in both salt efficiency and water savings through infrequent regeneration, and will provide plenty of capacity for an additional person.

If you consumed water at the more common average of 60 gallons/day X 3 ppl X 30 gpg, you would then require 5,400 grains/day.
40K / 5,400 = ~ 7 days between regeneration cycles. For efficiency, it is generally desirable to regenerate no more than 1X per week which the system and salt setting satisfies that expectation with 3 people.