Article reprinted from 2015/2016 Hydrotech - Product Catalog: Water Conditioning Products.

Water Softener Sizing is Based On:

• 60 gallons per person per day – total household use.
• Three day minimum between regenerations.
• Capacity between regenerations at factory salt settings or K label capacity.
• Number of people x 60 gallons per person x gpg of hardness x 3 days = capacity required between regenerations.
• Consult your factory representative for water that is 75 gpg or harder.

Water Softener/Iron Removal Combination Units

• This unit should be recommended only when dictated by special circumstances or the needs of the customer.
• The customer should be made aware that a separate iron filter and softener is preferred because it is a more efficient way to deal with the water.
• When recommending a combination unit, follow the guidelines provided in the specifications.

Water Consumption for Regeneration

The volume of water used during the regeneration process of a water softener will vary depending on:

• Amount and type of resin.
• Cycle time settings.
• Flow controllers.
• Salt settings.
• Tank diameter.

Generally, water usage for regeneration is based on the cubic feet of resin per water softener from a low of 30 gallons of water per cubic foot, up to a normal of 75 gallons of water per cubic foot, to a maximum of 100 gallons of water per cubic foot. Manufacturing specs and settings for each model size should be checked to verify exact amounts.

Three Day Sizing Method

The three day sizing method is used for the following reasons:

1. To determine the size of the water conditioner to be used.
2. To allow for reserve capacity between regenerations so the customer does not run out of soft water.
3. To provide the most economical operation cost.

Conversion Factors & Compensated Iron & Manganese

Total Hardness converted from ppm or mg/l to Grains/US Gallon (gpg)
ppm (mg/l) ÷ 17.1 = gpg

If there is a small amount of Iron or Manganese in the water, add the following compensated values:
Iron - ppm x 4
Manganese - ppm x 8

To arrive at the additional compensated load on the softener.

The Total ferrous Iron for the softener to remove should not be greater than 1.5 ppm.

The Total Manganese for the softener to remove should be greater than 0.75 ppm.

If the Total Equivalent Iron is less than 0.5 ppm, a Res-Up Feeder and Pro ResCare can be added as an optional safeguard against fouling or the bed can be cleaned occasionally by adding a small amount to the brine tank manually.

If the Total Iron is 0.5 - 1.5 ppm and or the manganese is 0.1 to 0.75 ppm, the softener can be sized accordingly but a Res-Up Feeder and Pro ResCare is required in addition to the softener to prevent iron fouling of the resin.

If the Total Iron is greater than 1.5 ppm, an Iron Filter is required as pre-treatment prior to the softener.