The Omnipure K2551 Inline 50% Calcite & 50% Corosex Filter. This filter is a mix of crushed calcite and hard magnesium beads which increase pH values above 7.

Features:

Cartridge Mix: 50% Calcite and 50% Corosex Media
Calcite neutralizes acidic or low pH waters to a neutral,
Less corrosive effluent
Corosex uses magnesium to adapt the filters to neutralize acidity by increasing the pH value.
Recommended Use Calcite only for PH levels 6.0 - 6.8. Use Calcite/Corosex for pH levels 5.5 - 6.0.

National Pipe Thread (NPT) Size Measured Against a Ruler*
Actual Diameter (Inches)	National Pipe Thread (NPT) (Fractional)
0.405"	1/8"
0.540"	1/4"
0.675"	3/8"
0.840"	1/2"

*NOTE: A very common misconception is that a 1/4" NPT measures as 1/4 inch on a ruler or tape measurer. However, that is not the case. NPT will measure larger in diameter. Above is a sizing reference to help clarify.

Corosex Inline

Omnipure - K2551-T33CAL - 10" x 2" Inline K-Series GAC/Calcite

Pentek - GS-10CAL/RO - 10" x 2" Coconut Shell Granular Activated Carbon & Calcite Inline Filter

Omnipure - K2551 - 10" x 2" Calcite/Corosex - For Higher pH