1. Determine your water's hardness in grains per gallon. Call your water authority or order 2. Determine your normal "service" flow and your intermittent (up to 2 hours) flow requirements. 3. Determine approximate gallons used per day. 4. Can your softener be off-line for 2 to 3 hours per day to regenerate? If not, then a continuous- duty system is required.

5. If you have well water, determine iron type and content with test kit. Clear water iron can be removed by compensating 5 grains of hardness for every ppm of clear water iron. For best results use a chemical-free iron removal system when >4 ppm of clear water iron or any amount of red water or iron bacteria is present.

6. Multiply the gallons of water used per day by the water hardness to determine the capacity required. Make sure you have compensated for iron; review intermittent flow and service flow rates; determine 24 hour needs. Select unit based on maximum capacity required. EXAMPLE: If your application requires 5000 gallons per day on 18 grain water with 2 ppm of clear water iron: 5000 x [18 + (2 x 5)] = 140,000 grains.