Phosphate & Coconut Shell GAC Filter Cartridge

White crust on the faucet. A kettle that scales up in weeks. A coffee maker or ice machine that keeps needing descaling. That is hardness coming out of the water as scale, and it builds wherever water is heated or left to dry.

This Phosphate & Coconut Shell GAC Filter Cartridge pairs two treatments in one stage. Polyphosphate helps keep hardness minerals in solution so they are less likely to form scale, and coconut shell granular activated carbon reduces chlorine taste and odor. It comes in four actual cartridge sizes that fit standard 2.5 x 10, 2.5 x 20, 5 x 10 and 5 x 20 inch housings, including Crystal Quest systems that specify this media combination.

At a glance

• Scale control without softening: phosphate keeps hardness minerals from depositing; it does not remove them
• No salt, no drain, no electricity: the media works as water flows through it
• Carbon in the same cartridge: coconut shell GAC for chlorine taste and odor
• Four actual sizes for countertop, under-sink and whole house housings
• Keeps your system's specified stage: a like-for-like replacement for the phosphate and GAC cartridge

What you are looking at

A drop-in filter cartridge holding a blend of phosphate media and coconut shell carbon, sized by actual diameter and length: 2-7/8" x 9-3/4", 2-7/8" x 20", 4-5/8" x 9-3/4" and 4-5/8" x 20". Cartridge color can change between production runs. Each end cap has 1-micron pads behind its openings.

How a phosphate filter cartridge works

Scale inhibition, not softening

Scale forms when calcium and magnesium carbonate come out of solution, which happens fastest when water is heated or evaporates. As water passes through the cartridge, a small amount of phosphate dissolves into it. Phosphate binds with hardness minerals and interferes with crystal growth, so the minerals tend to stay dissolved instead of building up as hard scale on heating elements, fixtures and glassware. The hardness is still in the water; it is simply less likely to deposit.

Why that is different from a softener

A water softener removes calcium and magnesium by ion exchange and needs salt and a drain. A phosphate cartridge removes nothing; it conditions the water. That makes it a compact choice for protecting a single appliance or a point-of-use system, and the wrong choice if you need soft water.

Coconut shell GAC

Activated carbon is honeycombed with microscopic pores that adsorb the compounds behind chlorine taste and odor. Coconut shell carbon is hard and dense with a high share of very small pores, which suits drinking water.

Why the media is consumed

Phosphate works by dissolving, so the media slowly depletes as water flows. Harder water and higher use draw it down faster, which is why scale coming back is a reliable sign the cartridge is due.

What it treats

Primary jobs:

• Scale buildup from hard water, by phosphate scale inhibition
• Chlorine taste and odor, by coconut shell GAC

Not designed to treat: hardness itself (the minerals stay in the water), bacteria and viruses, fluoride, nitrate, arsenic, lead and other heavy metals, or total dissolved solids. If you want soft water, use a water softener; for a full carbon stage with chloramine and VOC reduction, see the GAC Filter Cartridge. For salt-free scale control with Crystal Quest's own anti-scale media, see the Eaglesorb Anti-Scale Water Filter Cartridge.

Why Crystal Quest

• Two jobs, one housing. Scale inhibition and carbon taste control without adding a second stage.
• Exact replacement. The same media combination your system was set up with, listed by actual cartridge measurements.
• Over 1,000,000 people served since 1994. Crystal Quest builds under ISO 9001 quality management and has made water filtration in the USA for over 30 years.
• Lifetime support. Send us your part number and water test and our team will confirm the right cartridge and service plan.

Where it fits

• Systems that specify phosphate and coconut shell GAC: Crystal Quest countertop, under-sink and whole house cartridge housings
• Moderately hard water where you want less scale on fixtures and appliances without installing a softener
• Not the calcite cartridge: calcite raises low pH and adds minerals; phosphate controls scale on hard water. They solve opposite problems.

Pick the size printed on your current cartridge or in your order history: 2-7/8" x 9-3/4" (CQE-RC-04013), 2-7/8" x 20" (CQE-RC-04025), 4-5/8" x 9-3/4" (CQE-RC-04074) or 4-5/8" x 20" (CQE-RC-04079).

Common questions