Acid Neutralizers

An acid neutralizer is a whole-house water filter that raises the pH of acidic well water using a sacrificial media. Water enters the bottom of a tank packed with natural calcite (calcium carbonate) and dissolves a small amount of the mineral on its way up. That dissolved calcium raises the pH from a corrosive 4.0 to 6.9 range up to a neutral 7.0 to 7.5, which stops the water from leaching copper out of your plumbing and staining your fixtures blue-green.

Run the water through a calcite acid neutralizer. Calcite, a crushed natural marble (calcium carbonate), slowly dissolves into acidic water and raises the pH. For pH between 5.5 and 6.9, a calcite-only system raises the pH into the 7.0 to 7.5 range. For pH below 5.5, blend FloMag (magnesium oxide / Corosex) into the calcite at about 2 lbs per 50 lb bag (we'll bump it toward 3 lbs if your pH is stubbornly low) for stronger neutralization. The calcite dissolves as it works, so you top off the tank periodically: roughly every 12 to 24 months for a 1.0 cu ft tank, every 18 to 36 months for a 2.0 or 2.5 cu ft tank.

For most well water homes, a 2.5 cubic foot upflow non-backwashing calcite acid neutralizer is the best choice. It handles pH 4.0 to 6.9 (calcite alone covers 5.5 and up; add FloMag for the lower end), needs no electricity, no drain, and no salt, fits homes of 2 to 10 people, and uses an NSF/ANSI 61 certified Clack C1190 valve made in the USA. Smaller homes can size down to 1.0 or 1.5 cubic feet. Homes with visible sediment or very high simultaneous flow should choose a backwashing version (Fleck 2510SXT) so the bed self-cleans on a programmed schedule.

If your well water pH is below 7 AND you're seeing corrosion symptoms, yes. The clearest signals are blue-green staining on white sinks/tubs, pinhole leaks in copper plumbing, a metallic taste, or elevated copper / lead on a water test. If your test shows a borderline pH (about 6.5 to 7.0) with none of those symptoms, you can usually re-test in 6 to 12 months and act when the symptoms start. Acidic water is cumulative: every month of low pH water shortens the life of copper, brass, and water-touching appliances, so we'd rather get you sized when the symptoms first appear than after a pipe fails.

Calcite is natural calcium carbonate. It dissolves slowly and gently into the water and is the right media for moderately acidic water (pH 5.5 to 6.9). It raises pH into the 7.0 to 7.5 range and adds a small amount of calcium hardness (about 60 to 100 ppm, or roughly 4 to 6 grains per gallon) to the water as a side effect.

FloMag (also sold as Corosex) is magnesium oxide. It dissolves faster and corrects more aggressively. It's blended into the calcite bed (about 2 lbs of FloMag per 50 lbs of calcite, bumped toward 3 lbs for stubbornly low pH) when starting pH is below 5.5, where calcite alone can't keep up. The blend reliably handles pH down to 4.0 (we've dialed in blends for wells as low as pH 3.67). Pure FloMag would over-correct and raise pH too high, which is why it's always blended with calcite, not used alone.

About 60 to 100 ppm of calcium hardness (roughly 4 to 6 grains per gallon) is typical. The calcite is calcium carbonate, so the calcium it dissolves into your water shows up as hardness. Most acidic well water is naturally very soft (the same reason it's acidic), so most customers don't notice a real difference. If your water already tests above 7 gpg of hardness, or you're sensitive to scale, plan to install a water softener after the neutralizer. We bundle that as our 2-tank AN + softener package.

Most well water homes do fine with non-backwashing (upflow) calcite. It's the simpler install (no drain, no 120V outlet, no wastewater), the lower-cost system, and it works well for clean, sediment-free well water with pH between 4.0 and 6.9. Choose a backwashing (downflow) Fleck 2510SXT if your water has visible sediment or your household has very high simultaneous flow. If your water test shows iron, a dedicated iron filter upstream of the neutralizer is usually a better fit than relying on the AN to handle it; call us and we'll size both together. Backwashing AN systems self-clean the calcite bed on a programmed schedule (every 3 to 5 days by default) so it can't channel or crust.

Refill cadence depends on tank size and your starting pH. A 1.0 cu ft tank typically refills every 12 to 24 months; a 2.0 or 2.5 cu ft tank typically refills every 18 to 36 months. Lower starting pH and heavier daily water use shorten the cycle (we've seen well water cases needing a top-off every 4 to 8 months in extreme low-pH households). Our 1.0 cu ft tank holds about 100 lbs of calcite, our 2.5 cu ft holds about 250 lbs, and every tank ships with a side fillport so you can top it off without removing the valve or replumbing anything. We sell pre-bundled supply kits by tank size, or 50 lb bags of straight calcite if you'd rather top off as needed.