Clack Corosex®  Neutralising Media is a specially processed hard, bead-like magnesia,adapted for use in filters to neutralize acidity by increasing the pH value.

Corosex Neutralising Media




Corosex is mineral-based product used to raise low· pH water is magnesia (magnesium oxide, or MgO). Magnesia, which has been used for years as an antacid therapy for indigestion (Milk of Magnesia), can likewise be an effective acid-water neutralizer. Under the trade name of Corosex , the bead form is available in standard 10-40 U.S. mesh and granular in 8-16 U.S. mesh. Like Calcite, hardness will be added to the treated water. Magnesium oxide dissolves at a faster rate than natural calcite, which makes the product valuable when used with calcite. It has become very effective to use a mixture of calcite and corosex with a calcite/corosex ratio of 3: 1. This will extend the life of the neutralizing media bed to its maximum potential and reduce frequency of replacement.


On a per weight basis, Corosex® can neutralize five times more acidity than can calcite. This results in greatly reduced media usage for the same pH correction. Under certain low flow conditions, Corosex® may overcorrect and raise the pH beyond the desired level. For this reason, it is usually blended with calcite at a ratio that achieves the desired pH correction without over-correcting during lower flow conditions.

Where the feed water is greater than about 85 ppm or mg/l  of hardness, pH correction with Corosex® can cause hardness minerals to precipitate out of solution, resulting in cementing or solidification of the Corosex® mineral bed. To prevent this cementing effect, upflow service is generally recommended with hardness exceeding  85 ppm or mg/l. If downflow configuration is used, frequent backwashing should be undertaken to prevent hardening of the media bed. This is generally effective where the Corosex® to calcite blend does not exceed 50/50.


Corosex® Advantages:

  • fast acting
  • capable of large pH corrections – effective over a wide pH range of 4.5 to 6.0
  • certified to NSF/ANSI Standard 60

Corosex® Disadvantages:

  • may over-correct
  • increases water hardness



Corosex® is is manufactured by Martin Marietta Magnesia Specialties, LLC under the name FloMag® PWT 6×16.

Operating Conditions / Requirements:
Service Flow Rate: 5 to 6 GPM/ft2
Flow Direction: Upflow or Downflow
Backwash Flow Rate (Downflow Service): 10-12 GPM/ft2
Typical Freeboard: 50%
Minimum Bed Depth: 24 Inches
Recommended Bed Depth: 24-30 Inches
Recommended pH: 4.5 to 6.0
Weight: 75 lbs per Ft3



Additional information

Weight 1 kg
Dimensions 10 x 10 x 5

5, 10, 22.7