This is a replacement pre-filter cartridge for two HydroLogic water systems. The maker lists it as the Stealth-RO or smallBoy KDF/Catalytic Carbon Filter, built on KDF85 media plus granular activated catalytic carbon, and states it reduces iron, sulfur, chlorine, and heavy metals. It is a consumable cartridge, not a filter system: it drops into a Stealth-RO or smallBoy you already own. This page gives the maker’s published specs and replacement intervals for this exact part, and is explicit about the figures HydroLogic does not publish.
What it is
This cartridge is the upgrade option to the green coconut carbon pre-filter that HydroLogic systems normally ship with. The maker’s part page describes a translucent housing, which lets you see the media without pulling the cartridge. Activated carbon works by adsorption — dissolved contaminants bind to the surface of the carbon rather than being strained out by pore size, which is why a carbon stage is spent by volume treated rather than by visible clogging.
Specifications
| Product type | Replacement carbon pre-filter cartridge (upgrade option) |
|---|---|
| Media | Granular Activated Catalytic Carbon and KDF85 media |
| Reduces | iron, sulfur, chlorine, and heavy metals |
| Flow rating | 1 GPM |
| Dimensions (H x W) | 10" x 3" |
| Weight | 1.288 lbs |
| Housing | Translucent |
| Supersedes | HL 22060 |
| Maker part number | HGC741622 |
| Case pack (catalog) | 24/CS (distributor pack code) |
What it fits
Compatibility here is taken from the maker’s own listing for this part, not inferred from the title.
- Two named systems. HydroLogic publishes this cartridge as the Stealth-RO or smallBoy KDF/Catalytic Carbon Filter, and files it under both the Stealth RO and smallBoy replacement-filter categories on its own site.
- Replacing an older part number. The maker states it replaces HL 22060, so a system stocked under the old number takes this cartridge.
- Source water. The maker calls it great for well water, which is consistent with the iron and sulfur it lists as targets.
- Plumbing throughput. The 1 GPM rating is the flow the cartridge is rated for; a run that needs more throughput needs a larger HydroLogic filter body, not this one.
Replacement intervals (maker directions)
HydroLogic publishes a different service life for this same cartridge depending on which system it is installed in, because the two systems put different volumes through it:
- In a smallBoy: the maker directs replacement after 6,000 gallons filtered.
- In a Stealth-RO: the maker directs replacement after 2,000 gallons purified.
Track treated volume rather than calendar time — because carbon is consumed by adsorption onto its surface, a cartridge can be exhausted while still looking clean. HydroLogic does not publish an installation procedure on this part’s page; follow the filter-change steps in the manual for your own Stealth-RO or smallBoy system, where those steps are published.
Sources
- HydroLogic Systems — “Stealth-RO™ or smallBoy™ KDF/Catalytic Carbon Filter” maker product page (HTTP 200 via WAF-immune fetch_maker, retrieved 2026-07-19; PRIMARY and only product source; part number HGC741622 matches this listing’s supplier SKU): reduces iron, sulfur, chlorine, and heavy metals; rated at 1 GPM; great for well water; smallBoy replace after 6,000 gallons filtered; Stealth-RO replace after 2,000 gallons purified; replaces HL 22060; granular activated catalytic carbon; KDF85 media; translucent housing; dimensions (H x W) 10″ x 3″; weight 1.288 lbs: https://hydrologicsystems.com/products/kdf85catalytic-carbon-upgrade-filter-10×25-for-stealth-ro100200-and-small-boy
- Premier Hydro store catalog — distributor case pack code “24/CS” from the product title (CATALOG tier; the per-case unit interpretation is HELD, not a maker specification).
Reviews
There are no reviews yet.