When setting up a softener on water that has iron, you want to raise the hardness 3 grains for every part of iron (some will say 4-5 grains per part of iron). So with 2 ppm iron, you would raise the hardness 6 gpg or to 36 in your case. I would also recommend the use of Iron Out. This will keep the resin clean. If not, the resin may get fouled by the iron.