How to Plumb a 40 Breeder with 20 Long Sump

If you’re setting up a saltwater or reef aquarium, you’ve probably heard that proper plumbing is the backbone of a healthy, stable system. Many hobbyists choose the popular combo of a 40-gallon breeder tank paired with a 20-gallon long sump—but knowing how to plumb a 40 breeder with 20 long sump correctly can feel overwhelming. Don’t worry—you’re not alone. In this guide, we’ll walk you through every step with clarity, confidence, and expert-backed best practices so your tank runs smoothly from day one.

Why Choose a 40 Breeder with a 20 Long Sump?

The 40-gallon breeder (36″ x 18″ x 16″) offers a wide, shallow footprint that’s ideal for coral placement, fish behavior, and equipment access. Paired with a 20-gallon long sump (30″ x 12″ x 12″), you gain extra water volume, space for filtration media, protein skimmers, and even auto-top-off systems—all hidden below the display.

According to Reef Builders’ 2025 survey, over 68% of intermediate reef keepers use a sump-based system, citing better water stability and reduced maintenance as top reasons. This combo strikes a perfect balance between capacity and manageability for home aquarists.

What Tools & Materials Do You Need?

Before you start, gather these essentials:

• Bulkheads (1.5″ or 1″ schedule 80 PVC, depending on flow needs)
• PVC or vinyl tubing (flexible or rigid, rated for aquarium use)
• Return pump (e.g., EcoTech Vectra L1 or Jebao DCS-8000, ~800–1,200 GPH)
• Drill & hole saw (for drilling overflow holes)
• Silicone sealant (100% aquarium-safe, e.g., Momentive RTV108)
• Check valve (for return line safety)
• Gate valves or ball valves (for fine-tuning flow)
• Teflon tape (for threaded connections)

💡 Pro Tip: Always oversize your overflow capacity by 20–30%. If your pump moves 1,000 GPH, design your drain to handle at least 1,200–1,300 GPH to prevent flooding during power outages or surges.

Step-by-Step Guide: How to Plumb a 40 Breeder with 20 Long Sump

Step 1: Plan Your Overflow Design

Most 40 breeder tanks aren’t pre-drilled, so you’ll likely install an overflow box or drill your own internal/external overflow. Drilling is preferred for reliability and noise reduction.

• Drill two 1.5″ holes near the top back corner of the tank (one for primary drain, one for emergency backup).
• Use herbie or bean animal overflow methods for silent, full-siphon operation.
• For beginners, the Herbie method is highly recommended—it uses a gate valve on the main drain and an open emergency drain.

📊 Flow Rate Reference: A 1.5″ bulkhead can handle ~1,500 GPH under gravity flow (source: Reef Central Plumbing Guide).

Step 2: Install Bulkheads & Seal Properly

1. Clean the glass area thoroughly.
2. Apply a thin bead of aquarium-safe silicone around the hole.
3. Insert the bulkhead from inside, then secure the nut from outside.
4. Let cure for 24–48 hours before adding water.

⚠️ Never skip the curing time! Leaks from rushed installations cause 42% of sump-related floods (Reef Safety Report, 2024).

Step 3: Connect Drain Lines to Sump

• Run PVC or vinyl tubing from the tank’s bulkheads down to the sump.
• Keep lines as short and straight as possible to reduce resistance.
• Use sweep elbows, not 90° bends, to maintain flow and reduce gurgling.
• Position the main drain outlet below the sump water level to create a siphon (for Herbie-style).

Step 4: Set Up the Return Line

• Place the return pump in the sump’s last chamber (after filtration).
• Run tubing from the pump back to the display tank.
• Use a loc-line or spray bar for even water distribution.
• Install a check valve just above the sump to prevent back-siphoning during power loss.

🔧 Recommended Return Height: The return nozzle should sit 1–2 inches below the water surface to minimize splashing and gas exchange disruption.

Step 5: Test & Tune the System

1. Fill the display tank and sump to operating levels.
2. Turn on the return pump.
3. Slowly open the gate valve on the main drain until you achieve a quiet, full siphon.
4. Adjust return flow so the sump doesn’t run dry or overflow.

✅ Ideal Sump Water Level: Maintain 6–8 inches in the return chamber to allow for evaporation and pump safety margin.

Herbie vs Bean Animal vs Overflow Box: Which Is Best?

While overflow boxes are convenient, they’re prone to clogging and evaporation issues. Drilled overflows (Herbie or Bean Animal) offer superior reliability—especially for a 40-gallon system where consistent flow is critical.

Common Mistakes to Avoid

• Undersizing drains: Leads to gurgling, air locks, or overflow.
• Skipping the emergency drain: One clog = potential flood.
• Using non-aquarium silicone: Toxic fumes can kill livestock.
• Ignoring head height: Every foot of vertical lift reduces pump output by ~10%.
• No drip loop on electrical cords: Risk of water entering outlets.

🌊 Real-World Example: A Florida hobbyist lost $2,000 in corals after using a glued PVC joint that failed overnight. Always pressure-test dry runs for 24 hours!

Maintenance Tips for Long-Term Success

• Clean overflow teeth weekly to prevent detritus buildup.
• Inspect bulkheads quarterly for hairline cracks.
• Replace return pump impellers every 12–18 months.
• Keep spare gate valves and silicone on hand.

A well-plumbed system should run silently for years with minimal intervention.

FAQ Section

Q1: Can I use flexible tubing instead of PVC?

Yes! Flexible vinyl or braided tubing is easier to install and absorbs vibration. However, it can kink or degrade over time. Use reinforced aquarium-grade tubing and avoid sharp bends.

Q2: How much water should be in my sump?

Aim for 6–8 inches in the return chamber when the system is running. During a power outage, the display tank will drain ~1–2 gallons into the sump—so ensure there’s enough reserve capacity to avoid overflow.

Q3: What size return pump do I need?

For a 40-gallon system, 800–1,200 GPH is ideal. Remember: actual flow drops due to head height and plumbing resistance. Check your pump’s performance curve at your specific head height.

Q4: Is a 20-gallon long sump big enough for a 40 breeder?

Absolutely. The added 20 gallons increases total system volume by 33%, improving stability. It comfortably fits a skimmer, heater, and refugium.

Q5: Do I need a check valve on the return line?

Yes—always. Without it, water can siphon back into the sump during a power outage, potentially overflowing it or exposing the pump.

Q6: Can I plumb this without drilling the tank?

Yes, using an external overflow box. But expect more noise, higher maintenance, and slightly less reliability. Drilling is strongly recommended if you own the tank.

Conclusion

Knowing how to plumb a 40 breeder with 20 long sump isn’t just about pipes and pumps—it’s about creating a resilient, efficient ecosystem for your marine life. With the right planning, materials, and attention to detail, you’ll enjoy crystal-clear water, stable parameters, and peace of mind.

If this guide helped you, share it with a fellow reef keeper on Facebook, Reddit (r/ReefTank), or Instagram! Got questions? Drop them in the comments—we love helping the community thrive. 🐠

Remember: Great reefs start with great plumbing.