I have a "bladder tank" at the well. From there the water goes to a holding tank.
Then a "holding tank" by the house. The water comes from the well into the tank and is injected with chlorine, goes thru the carbon tank and into the house.
Where is the line from the solution feeder pump attached to the water line? Is it between the pressure tank and the retention tank, what you are calling a "holding tank" or does the chlorine go into the water in the tank?
What size is that retention tank in gallons?
What size is the carbon filter in cubic feet? There may be a label on it with a model number like 948 or 1054, that would tell me the amount of carbon.
How frequently does the carbon backwash?
Has this equipment ever worked right, meaning there was no odor or iron staining?
With a pH of 6.0, you do not need a mixed bed, calcite and corrosex (Flo Mag) acid neutralizer filter.
And again, no one can tell you what cubic foot size carbon or AN filter or softener until they know how many people, how many bathrooms and what type fixtures are in them like large tubs or showers etc.. That's so they can calculate your peak demand water flow gpm. Then any filter or softener must be sized to be able to treat that gpm. Otherwise they are just throwing equipment at the problem, and you're suffering now because of the previuos guy doing that, so don't let it happen again. Doing that is like a car salesman selling you a F-250 pick up because you say you want to haul manure for your organic garden and he doesn't ask how big the garden is or how much manure you have to haul, and you actually need a F-450.
Solution feeders are a major PIA to get to work right and maintain and that's why I have refused to sell them for over 10 years.