Keeping your PENN-PLAX Cascade series internal filter units running at peak performance means choosing the right replacement filter cartridges and media. This guide — “Replacement Filter Cartridges and Media for PENN-PLAX Submersible Internal Filter Units” — explains the best replacement media for Cascade 170 (CIF4), Cascade 300 (CIF1), Cascade 400 (CIF2) and Cascade 600 (CIF3). You’ll find quick, SEO-friendly specs for model compatibility, physical dimensions, materials, filtration capacity, expected lifespan, standout features, common third-party options, and simple replacement timing advice. Whether you keep a small desktop tank or a heavily stocked aquarium, swapping worn foam pads, exhausted activated carbon, or clogged composite cartridges on schedule keeps water crystal clear, reduces ammonia and nitrates, and preserves beneficial bacteria colonies. This post helps hobbyists and store owners quickly identify correct parts, avoid fitment errors, and choose economical third-party replacements without sacrificing performance. Use the short, scannable rows below as a checklist when ordering replacements online or in-store — and bookmark this page for seasonal maintenance reminders. The recommendations are practical, conservative, and aimed at extending filter life while protecting aquatic health.
Replacement Media for Cascade 170 Fully Submersible Internal Filter (CIF4)
Cascade 170 (CIF4)
- Model compatibility: Designed for PENN-PLAX Cascade 170 (CIF4) internal filter — also fits many small universal internal filter housings with similar tray size.
- Dimensions: Compact cartridge roughly 80–95 mm long by 30–40 mm diameter (verify exact measure before purchase).
- Material: Coarse mechanical foam pad + small pouch of activated carbon in a single composite cartridge or modular foam + carbon combo.
- Filtration capacity: Effective for light-to-moderate bio/mechanical and chemical filtration in aquariums up to ~20–30 gallons.
- Life span: Foam: 4–8 weeks (cleanable); carbon pouch: 2–4 weeks (replaceable); composite cartridges: 1–3 months depending on bioload.
- Important features: Easy slide-in tray fit, washable foam for repeated use, quick-swap carbon for odor/tannin removal.
- Third-party options: Universal small internal filter foams and replaceable carbon sachets from major aquarium brands usually fit — check tray length and width first.
- When to replace: Rinse foam every 2–4 weeks; replace carbon every 2–4 weeks and composite cartridges every 1–3 months or when flow drops noticeably.
Replacement Media for Cascade 300 Fully Submersible Internal Filter (CIF1)
Cascade 300 (CIF1)
- Model compatibility: Fits PENN-PLAX Cascade 300 (CIF1) and many mid-size internal filter trays with similar fittings.
- Dimensions: Medium cartridge ~110–130 mm long and ~35–45 mm diameter; confirm tray depth before ordering.
- Material: Multi-stage pack: dense mechanical foam, finer polishing pad, and activated carbon/chemical media sachet.
- Filtration capacity: Suited to moderate bioloads in tanks roughly 30–50 gallons — balances mechanical, biological and chemical functions.
- Life span: Mechanical foam: 6–10 weeks (cleanable); polishing pad: 4–8 weeks; carbon/chemical: 2–6 weeks;
- Important features: Layered filtration for clarity and odor control, modular inserts let you customize media for planted or heavily stocked tanks.
- Third-party options: Many aquarium supply brands make medium-sized cartridge kits and foam pads compatible with CIF1 — match dimensions and tray shape.
- When to replace: Clean foam monthly, swap carbon every 3–6 weeks or when water discolors/odors occur, replace composite packs when flow or clarity declines.
Replacement Media for Cascade 400 Submersible Aquarium Filter (CIF2)
Cascade 400 (CIF2)
- Model compatibility: Intended for PENN-PLAX Cascade 400 (CIF2); fits larger internal filter trays with the same mounting geometry.
- Dimensions: Larger cartridge ~140–170 mm long and ~45–55 mm diameter — confirm exact sizing against your unit.
- Material: Combination of coarse and fine foams, bio-media (ceramic/porous rings) option, plus activated carbon or chemical media sachet.
- Filtration capacity: Handles medium-to-high bioloads in aquariums ~40–75 gallons when properly staged.
- Life span: Coarse foam: 8–12 weeks (cleanable); bio-media: 6–12 months (do not replace unless damaged); carbon: 3–6 weeks.
- Important features: Space for biological media, greater surface area for bacteria, adaptable trays that accept bulk media for heavy stocking.
- Third-party options: Generic long foams, ceramic bio-rings, and carbon pouches from reputable suppliers fit well if dimensions align.
- When to replace: Rinse foams monthly, refresh carbon every 3–6 weeks, top up bio-media only if physically degraded or after chemical treatments.
Replacement Media for Cascade 600 Fully Submersible Internal Filter (CIF3)
Cascade 600 (CIF3)
- Model compatibility: Built for PENN-PLAX Cascade 600 (CIF3) — also compatible with other large internal filter housings with similar tray sizes.
- Dimensions: Large multi-stage cartridge area ~170–210 mm long and ~50–65 mm diameter; measure your tray to confirm fit.
- Material: Heavy-duty coarse foam, fine polishing pads, bulk biological media (ceramic rings/sponge blocks) and larger carbon/chemical packs.
- Filtration capacity: Designed for high bioload tanks up to ~80–100+ gallons when used as directed and paired with adequate flow.
- Life span: Coarse foam: 8–12+ weeks (cleanable); bio-media: 6–18 months (long-lasting); carbon: 3–6 weeks depending on contamination levels.
- Important features: High surface area for nitrifying bacteria, modular media bays for customized filtration, robust flow handling.
- Third-party options: Bulk foam sheets, large ceramic rings, and oversized carbon sachets from third-party brands typically work — always verify measurements.
- When to replace: Clean foams regularly (every 2–6 weeks depending on load), replace carbon monthly or when effectiveness drops, replace bio-media only when worn or after medication exposure.
Conclusion: Choosing the correct replacement filter cartridges and media for your PENN-PLAX Cascade internal filter keeps water quality high, prolongs equipment life, and protects fish health. Match cartridges by exact tray dimensions and intended function — mechanical foam for debris, biological media for bacterial colonization, and activated carbon for chemical and odor control. Clean washable foams frequently, swap carbon on a schedule, and reserve full cartridge replacement for when flow or clarity suffers. When in doubt, measure the filter tray and opt for reputable third-party media with clear sizing to avoid fitment issues. Regular maintenance and timely media replacement deliver the best performance from Cascade 170, 300, 400, and 600 units.
For more Replacement Filter Cartridges and other PENN-PLAX Products, visit PENN-PLAX Store on Amazon and PENN-PLAX Website