Our Philosophy
Contact Us

Clack Corosex®

By neutralizing the free carbon dioxide in water, Corosex can correct acidic water conditions and render it less corrosive. Corosex, being a highly reactive magnesium oxide, is used most effectively where pH correction is substantial or high flow conditions are in use. pH correction and media con sump tion are affected by a number of water chemical variables. Being soluble to acidity, Corosex will slowly dissolve and will need to be replenished periodically.

On a per weight basis, magnesium oxide can neutralize five times more acidity than can calcium carbonate. This results in greatly reduced chemical usage for the same pH correction. Please note; under certain low flow conditions, Corosex may over correct and create a highly basic (high pH) condition.

Under certain hardness conditions, pH correction can cause hardness minerals to precipitate out of solution, resulting in cementing or solidification of the Corosex mineral bed. Upflow service is generally recommended with hardness exceeding five grains per gallon. (Always use an in-line filter ahead of an upflow system to prevent plugging of the lower distribution screen.)

As Corosex’s magnesium oxide neutralizes the water, it will increase hardness and a softener may become necessary after the neutralizing filter. Corosex can be effectively combined with Clack Calcite to combine the high flow neutralization properties of Corosex, along with the slower reacting low flow properties of Calcite, reducing potentially high basic properties due to overcorrection.


  • High degree of activity and speed of correction allowing high flow
  • High capacity...less chemical usage


  • Color: Brownish white
  • Bulk Density: 75 lbs./cu. ft.
  • Mesh Size: 6 x 16
  • Specifi c Gravity: 3.6 gm/cc
  • Effective Size: 1.4 mm
  • Uniformity Coefficient: 1.7
  • Composition: MgO 97% min.


  • Downflow service is generally satisfactory on waters with a hardness of less than fi ve grains/gal. or where it’s combined with Calcite at least 50-50. Upflow service is generally recommended with hardness exceeding five grains/gal. to prevent cementing of the Corosex bed
  • Use distributors designed for upflow applications
  • A gravel support bed is recommended
  • Water pH range: 4.5-6.0
  • Bed depth: 24-30 in.
  • Freeboard: 50% of bed depth (min.)
  • Backwash frequently to prevent possible cementing
  • Backwash rate: 10-12 gpm/sq. ft.
  • Service flow rate: 5-6 gpm/sq. ft. but may be modified to adapt to local
  • Max usage 100 mg/L


  • Corosex is packaged in 50 lb. bags (.66 cu.ft.)
  • 60 bags are on a complete pallet