AN filters do not require rebeding unless they are not backwashed properly.
All that has to be done is to add new mineral when needed. That needs to be done when the mineral level is down about one bag worth of mineral. And the filter tank should have a top dome hole plug instead of having to remove the control valve to do it.
Brown yellow could be iron, tannin, or turbidity (discolored) from the aquifer or something with the well. Do you have a rock bore or screened well? Being from MA says rock bore normally.
Post the test results and what brand control valve and the size of the equipment, or post pictures.