Red Flint Gravel, 1/2" x 1/4", 100 Bag

Red Flint support gravel in the 1/2" x 1/4" grade, packaged in a 100 lb bag. This coarse, high-density silica gravel is used as the bottom support bed (underbedding) in backwashing water filters and softener mineral tanks, holding the finer filter media above the distributor and preventing it from washing into the underdrain.

• Product: Red Flint underbedding / support gravel
• Grade: 1/2 inch x 1/4 inch coarse particle size
• Package: bulk 100 lb bag
• Role: bottom support layer beneath the primary filter media
• Properties: dense, hard, sub-angular silica with very low acid solubility
• Keeps the distributor basket clear and stabilizes the media bed during backwash

Load this coarse grade first as the base layer in a mineral tank, then add progressively finer gravel and your working media on top. A common choice when bedding calcite, filter media, or softening resin in residential and light-commercial tanks. Sold by the 100 lb bag; order enough to build the support bed to the depth your tank size requires.

The underbed that makes filtration work

Red flint gravel in the 1/2 x 1/4 grade is a graded support media that goes in the bottom of a mineral tank beneath the working media. Its rounded, uniformly sized stone creates a stable base that keeps finer filtration media from packing down onto the distributor and helps distribute both service and backwash flow evenly across the full cross-section of the bed.

Why it matters and how to use it

Without a proper gravel underbed, media can channel, backwash unevenly, or migrate into the distributor and out to service. Red flint is chosen for its hardness and low acid solubility, so it stays put and does not degrade the water. It is sold by the bag for building or rebedding softeners and filters; tell us your tank diameter and we will help you calculate how much support gravel and working media your rebed needs.

Layering a rebed

In a typical rebed the coarsest gravel goes in first around the lower distributor, with finer grades layered above before the working media is added, so flow steps down smoothly through the profile. Getting the underbed right the first time saves you from channeling problems that are frustrating to diagnose later, which is why we walk customers through the layering and quantities for their specific tank.