Not really knowing what I'm talking about, but I think you also have to take
into account the dissolved iron in the water. so much ppm of iron equates to
so much grains of hardness.

Check here if you don't get any answers:
http://www.qualitywaterassociates.co...wforum.php?f=2

"1_Patriotic_Guy" wrote in message
ink.net...
What is the formula for calculating water softener regeneration? If I know
the grains per gallon (hardness) is 15 ppm, and the size of the resin bed
is
41.6 pounds of resin OR .8 cubic feet AND the RESIN cylinder is 10"
diameter
by 35 inches tall. And if I can read my water meter to see how much water
I
am using daily.

How do I calculate how often the water softener should regenerate (e.g. in
terms of water useage)?

Thanks in advance,

Andy