Hydro-Logic Big BOY – 4.5″ x 20″ Refillable Filter Cartridge With Carbon/KDF85


Hydro-Logic KDF85 Carbon Replacement Filter

The Hydro-Logic KDF85 /Carbon Replacement Filter is designed to enhance your water filtration system, making it ideal for users with specific water quality concerns.

Key Features:

Effective Filtration: This filter combines KDF 85 and Granular Activated Catalytic Coconut Shell Carbon to address various water issues effectively.

Contaminant Removal: It removes iron, sulfur, and unpleasant odors like the rotten egg smell from your water, ensuring a clean and fresh water supply.

Filter Size: The filter measures 4.5″x20″, fitting perfectly into standard Big Blue Housings, making it a convenient choice for your filtration system.

Specialized Media: The unique blend of catalytic carbon and KDF85 media works to remove or reduce iron, hydrogen sulfide, scale, bacteria, and algae from your water supply.

Cost-Effective: This filter offers the benefits of competitive iron removal systems at a fraction of the cost.
Easy Replacement: No media regeneration is necessary, making cartridge replacement simple.
No Backwashing: Unlike some systems, this filter doesn’t require backwashing.
Wide pH Range: Effective filtration occurs within a pH range of 6.5 to 8.5.
Odor Reduction: It removes both iron and hydrogen sulfide, eliminating unpleasant smells.
Safe for Drinking Water: The filter does not introduce harmful chemicals into your water, ensuring safe drinking.


This system is suitable for water with low to moderate ferrous (dissolved) iron or hydrogen sulfide contamination. It is most effective when iron and hydrogen sulfide levels are less than 5 ppm and the pH is between 6.5 and 8.5. The filter can also remove ferric iron through mechanical filtration.

Filter Life:

The filter’s lifespan depends on the contamination level and daily water consumption. Typically, it lasts for about 20,000 gallons in a residential setting. To extend the filter life, consider using a sediment pre-filter.

Common Water Issues:

Rusty Stains: Excess iron.
Black Stains: Excess manganese.
Rotten Egg Smell: Hydrogen sulfide (H2S).

How it Works:

KDF85 media serves as a catalyst, transforming soluble iron cations into insoluble ferric hydroxide, which is then trapped in the filter. Hydrogen sulfide is converted into an insoluble sulfide precipitate and filtered. Ferric iron is removed through mechanical filtration.

Specifications & Operating Conditions:

Housing Material: Polypropylene
Maximum Flow Rate: 3 Gallons Per Minute
Operating Temperature Range: 40-100°F
Maximum Pressure: 90 PSI
pH Level: 6.5 to 8.5
Recommended Dissolved Oxygen: Iron level in ppm x 0.6
Maximum Iron Level: 5 ppm

Enhance your water quality with the Hydro-Logic KDF85 Carbon Replacement Filter.


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