Neutralizing Filters

The water is passed through a bed of calcite (CaCo3) sometimes augmented with corosex (MgO) utilizing either a down-flow or up-flow water path. Contact time is important, but the bigger the diameter of the unit the greater the backwash flow rate requirement. The media(s) are "sacrificial" and are dissolved by the acidic water.

Hardness is increased as a by-product of treatment (I use 50 mg/l as a rule-of-thumb). Typically, annual service to replenish the media(s) is required.

Automatic "down-flow" system:

• effective from pH 6.0
• also acts as a "filter"
• typical residential unit cycles every 6 days using approximately 150 gallons at a peak rate of 5.0 gpm
• average residential installed cost: $1000 - 3,000

Non-backwash "up-flow" neutralizer:

• effective from pH 5.5
• no backwash discharge
• average residential installed cost: $700 - 1,000

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