CaddyStack™ – Modular Filter Tower Extensions & Spare Parts
These CaddyStack™ Modular Filter Tower Extensions are individual replacement and expansion components designed to work with the
CaddyStack™ – Modular Filter Tower (Filter Sock Replacement Kit)
This product page is intended for reef keepers who already own a CaddyStack™ Starter Kit and want to:
- Replace a specific part
- Add more filtration stages
- Experiment with different media configurations
- Build out additional towers
New to CaddyStack™?
If you don’t already own a Starter Kit, we strongly recommend starting here:
CaddyStack™ – Modular Filter Tower (Filter Sock Replacement Kit)
Starter Kits include all core modules needed to build a complete system.
What These Parts Are For
CaddyStack™ Extensions allow you to customize and fine-tune filtration by adding or swapping individual modules instead of replacing your entire setup.
Each part:
- Twist-locks into existing CaddyStack™ towers
- Is fully compatible within its size category
- Lets you expand or modify your filtration anytime
These are not standalone filtration systems — they are modular building blocks for your existing CaddyStack™ platform.
Available Sizes
Spare parts are available in:
- 2"
- 2.75"
- 4"
- 7"
All modules keep the same height system — only the diameter changes.
CADDYSTACK™ EXTENSIONS – EXACT DIMENSIONS (READ BEFORE BUYING)
These are individual parts — NOT full kits.
All components are sized to match your existing CaddyStack™ system.
2" CaddyStack™ Parts
Compatible System Diameter: 2" class (58mm mount)
- Circle Mount: 58mm diameter × 5mm tall
- Short Tube: 47mm diameter × 23mm tall
- Short Cage: 47mm diameter × 23mm tall
- Tall Tube: 47mm diameter × 58mm tall
- Tall Cage: 47mm diameter × 58mm tall
2.75" CaddyStack™ Parts
Compatible System Diameter: ~2.5"
- Circle Mount: 2.56" diameter × 0.24" tall
- Short Tube: 2.48" diameter × 1.26" tall
- Short Cage: 2.48" diameter × 1.26" tall
- Tall Tube: 2.48" diameter × 3.19" tall
- Tall Cup: 2.48" diameter × 3.19" tall
- Tall Cage: 2.48" diameter × 3.19" tall
4" CaddyStack™ Parts
Compatible System Diameter: ~4"
- Circle Mount: 4.04" diameter × 0.31" tall
- Rectangle Mount: 7" length × 4.33" width × 0.98" tall
- Short Tube: 3.46" diameter × 1.26" tall
- Short Cage: 3.46" diameter × 1.26" tall
- Tall Tube: 3.46" diameter × 3.31" tall
- Tall Cup: 3.46" diameter × 3.31" tall
- Tall Cage: 3.46" diameter × 3.31" tall
7" CaddyStack™ Parts
Compatible System Diameter: ~7"
- Circle Mount: 7" diameter × 0.63" tall
- Short Tube: 6.30" diameter × 1.46" tall
- Tall Tube: 6.30" diameter × 3.19" tall
- Tall Cup: 6.30" diameter × 3.19" tall
- Tall Cage: 6.30" diameter × 3.19" tall
Available Modular Components
Mounting Options
Circle Mount
- Designed for standard round filter sock openings (including WATERBOX)
- Common in most sump systems
- Drops directly in for even flow
Square Mount (2.75" Only)
- Designed for flat-edge AIO chambers
- Works with systems like:
- UNS AIO
- Landen
- Hello Reef
- Dimensions: 2.5" × 2.5" × 2.75"
Rectangle Mount (4" Only)
- Designed for rectangular filter sock holders
- Compatible with systems using:
https://www.eshopps.com/product/rectangular-filter-sock/ - Allows you to convert a rectangular sock chamber into a 4" CaddyStack™ system
Short Modules (1" Tall)
Short Cage Module
- Open, high-flow design
- Ideal for quick mechanical filtration
Short Tube Module
- Solid sidewalls
- Forces water downward through media
Tall Modules (3" Tall)
Tall Cage Module
- Open design for maximum flow
- Ideal for carbon, biomedia, or high-flow setups
Tall Tube Module
- Forces water through media for better contact time
- Great for layered filtration setups
Tall Cup Module
- Works like a traditional filter cup
- Drop in and fill with:
- Filter floss
- Pads
- Carbon
- GFO
- Biomedia
To clean: replace media — no washing socks
Why Buy Extensions Instead of Another Kit?
CaddyStack™ is built as a long-term filtration system, not a disposable one.
Extensions let you:
- Replace worn parts
- Expand for higher bioload tanks
- Fine-tune filtration over time
- Customize flow and media strategy
Expandable by Design
Your system grows with your reef.
You can:
- Stack additional towers
- Mix and match modules
- Reconfigure anytime
Reef-Safe & Built to Last
- Printed in reef-safe PETG
- No raw metal
- No exposed magnets
- Designed for long-term saltwater use
- Rigid construction that won’t collapse
Important Notes
- These are extensions only
- A Starter Kit is required
- Parts only connect within the same size system
- Media not included
Designed, manufactured, and shipped by Printed Reef