RAW- KDF-55 Balls

Filtration media Redox

KDF-55 Balls are sold as a copper–zinc redox medium of the KDF-55 grade, the grade made for free chlorine and dissolved heavy metals.

• Made of: Copper and zinc, per the product name; branded KDF 55 is about 50% copper and 50% zinc

• Form: Balls

• Main job: Turns free chlorine into chloride

• Used in: Waslix custom layered cartridges; also sold loose by weight

What it does

Zinc in the medium gives up electrons to substances dissolved in the water. Free chlorine becomes chloride, and dissolved metals such as lead and mercury come out of the water onto the medium's surface.

• Reduces free chlorine: in a shower-filter test published by the maker, KDF 55 granules removed 96–100% at hot-shower temperatures and 83–91% at 28–29 °C; an independent column study found 90% or more

• Reduces dissolved lead and mercury: the maker states KDF 55 can remove up to 98% of soluble lead and mercury, and the independent study found 92% for lead; capacity is limited, and these figures do not cover lead particles

• Other dissolved metals: the same study found 88% nickel reduction, and peer-reviewed lab and column tests found copper–zinc near 50% copper removes hexavalent chromium by chemical reduction

• Adds some zinc: copper–zinc media release zinc as they work; in a published patent test, 1 kg of KDF 55 granules raised dissolved zinc from under 0.1 mg/L to about 2.4–3.3 mg/L, under the EPA's 5 mg/L taste guideline

Evidence: manufacturer data Most of these figures come from the maker of KDF 55 granules; one independent column study of 50/50 copper–zinc media found similar results for chlorine and lead. They describe the KDF 55 alloy, not tests of these balls.

Where it goes in your filter

Copper–zinc works within seconds, so it sits near the inlet and takes the chlorine load off the carbon layers that follow.

• Layer position: Near the inlet, ahead of activated carbon; never the last layer before the outlet

• Pairs well with: Activated carbon after it, which handles the organic chemicals copper–zinc does not

• Keep in mind: Works best in warm water and at pH 6.5–8.5 (maker's range); not a chloramine medium; iron and sulfide deposits clog it on well water

Specifications

Handling & care

• Before first use: Rinse until the water runs clear, then run a new cartridge to drain for a few minutes

• Storage: Keep sealed, cool and dry, away from food; avoid breathing dust and wear eye protection when pouring

• Replacement: No service life is published for this form; replace it with the cartridge, or sooner if chlorine taste or smell returns

Common questions

How well any medium works depends on your water, the flow rate, contact time and the other layers in the cartridge. This page describes the loose medium, not a certified filter system.

A copper–zinc redox medium, sold as the KDF-55 grade, for the inlet end of a layered cartridge. That grade turns free chlorine into chloride and reduces dissolved metals such as lead and mercury, taking load off the carbon that follows.