Usually, a backwashing acid neutralizer is only recommended if your water contains iron or heavy sediment. You want to ensure the bed does not become fouled with either the iron or the sediment.
We recommend never installing a unit smaller than 1.5 cubic foot. Although we do sell 1.0 cubic foot systems, 95% of the time they're too small for most households.
The key to an acid neutralizer is contact time of the water coming in contact with the filter media. The larger the media surface, the greater the contact time - especially during peak water usage like showers and washing laundry.