Need help sizing a softener for a fluctuating family size.

[Maher871]

I need help in sizing a water softener. The Hardness is 17gpg, 3/4” water service on City water, no Iron and 2 full bathrooms. The problem is we are a family of 5 and when the kids are away at school we are 2. Daily water use can be anywhere on average from 133 gal to 288 gallons a day. I thought I had it all figured out using a Fleck 5600SXT, 1.5 cubic foot of 10% Purolite C100E resin until I got the last water bill showing 12,000 gallons used for the quarter when it was normally 26,000 gallons. I don’t want to over think this but I want to make sure it’s sized right. Thanks for your help.

 

[John Gayewski]

I would size it for the max water usage.

 

[Sponsor]

 

[Reach4]

At 133 gallons per day, I predict you would regen 1.5 cuft about every 13 to 14 days.
At 288 gal/day, I get about 6 days... not terrible, but usually you go for 7 or more.

So going for 2 cuft raises that to about every 8 or 9 days for 288, and 18 or 19 days for 1.33

So it looks like the 2 cuft of resin in the 12x52 would be a little better choice, but it is not overwhelming.

This presumes setting the softener to use about 7.5 lb/cuft salt, and setting the hardness settting to 19 (to compensate for high hardness).

 

[Bannerman]

Your water bill will specify all water consumed which will exceed the soft water utilized by your family. Additional water that will be consumed will include that utilized for irrigation, and the water the softener utilizes for regeneration.

Greater softener capacity will typically result in less water needed per month/year for regeneration. To obtain the best balance of salt efficiency, soft water quality & usable capacity (lower frequency for regeneration), the usual recommended settings will be 24,000 grains usable capacity per cubic foot of resin which will require 8 lbs salt per cubic foot to regenerate.

Using these settings, a 1.5 ft3 softener (48K grains Total Capacity) will provide up to 36,000 grains usable capacity (36,000 / 19 GPG = 1,894 gallons) while consuming 12 lbs salt per cycle.

A softener containing 2 ft3 resin (64K grains Total Capacity) will provide up to 48,000 grains usable capacity (2,526 gallons) while using 16 lbs salt each cycle.

Since your water source is municipal which will be chlorinated and will therefore contain no iron for the softener to remove, the usual recommended regeneration frequency is > 7-days, but less than 30-days. Even if 12,000 gallons is consistently consumed per quarter (3,000 gallons/month = 100 gallons/day), a 2ft3 unit will likely need to regenerate every 24-25 days which is perfectly OK.