Aquaponics — the combination of aquaculture (fish farming) and hydroponics (soilless plant growing) — is one of the most rewarding DIY projects you can build with a used IBC tote. A single 275-gallon container provides enough volume for both a fish tank and a grow bed, creating a self-sustaining ecosystem that produces fresh vegetables and protein with minimal inputs.
How Aquaponics Works
The system operates on a simple biological cycle: 1. Fish produce waste (ammonia) in the water 2. Beneficial bacteria convert ammonia to nitrites, then nitrates 3. Plants absorb nitrates as fertilizer, cleaning the water 4. Clean water returns to the fish tank 5. The cycle repeats continuously
This means no soil, no chemical fertilizers, and minimal water loss (only through evaporation and plant transpiration). A well-designed IBC aquaponics system uses approximately 90% less water than traditional soil gardening for equivalent food production.
What You Need
Materials: - 1 used IBC tote (275-gallon, food-grade preferred) - Water pump (400-600 GPH submersible pump) - Air pump with air stones (for fish oxygenation) - Bell siphon components (1.5" PVC standpipe, 3" PVC bell, 4" PVC media guard) - Expanded clay pellets (LECA) — approximately 4-5 cubic feet - Plumbing: 3/4" PVC pipe, elbows, unions, bulkhead fittings - Aquarium-safe silicone sealant - Fish (tilapia, goldfish, or koi depending on climate) - Seedlings or seeds for your grow bed
Tools: - Angle grinder or reciprocating saw with metal-cutting blade - Jigsaw with fine-tooth blade (for cutting HDPE) - Drill with hole saw bits (1.5", 3/4") - Measuring tape and marker - Safety glasses and gloves
The Cut: Creating Two Sections
The key to an IBC aquaponics build is cutting the tote to create two functional sections:
Fish Tank (bottom section): The lower 2/3 of the IBC becomes your fish tank. This gives approximately 180-200 gallons of fish habitat.
Grow Bed (top section): The upper 1/3, flipped upside down, becomes a shallow grow bed approximately 12 inches deep.
### Cutting Instructions:
1. Mark your cut line at approximately 14-16 inches from the top of the cage (this becomes the depth of your grow bed when flipped) 2. Using the angle grinder, cut through the steel cage bars along your line 3. Using the jigsaw, cut through the HDPE bottle along the same line 4. Smooth all cut edges — steel with a file, HDPE with sandpaper 5. The top section should now lift off. Flip it upside down — it becomes your grow bed tray
Building the Stand
The grow bed must sit above the fish tank. Options: - Use the original cage top frame as a support (weld or bolt additional cross-members) - Build a wooden frame from treated 4x4 lumber - Use concrete blocks at the corners
The grow bed lip should sit approximately 4-6 inches above the fish tank water level. This provides clearance for the bell siphon drain.
Plumbing the System
Water flow path: Fish tank → pump → grow bed → bell siphon → drain back to fish tank
1. Install the submersible pump in the fish tank 2. Run 3/4" PVC from the pump up to the grow bed (enter through a drilled hole in the grow bed wall) 3. Install a bulkhead fitting where the pipe enters the grow bed 4. Run distribution pipe across the grow bed with small holes drilled every 6 inches for even water distribution 5. Install the bell siphon at the lowest point of the grow bed: - 1.5" standpipe through a bulkhead fitting in the grow bed floor (set height to desired water level — typically 1 inch below media surface) - 3" bell over the standpipe (creates the siphon action) - 4" media guard around the bell (prevents clay pellets from clogging) 6. The standpipe drains directly back into the fish tank below
The Bell Siphon: How It Works
The bell siphon is the heart of a flood-and-drain aquaponics system: - Water fills the grow bed until it reaches the top of the standpipe - The bell traps air and creates a vacuum as water begins to flow - Once siphon action starts, the grow bed drains rapidly - When water level drops below the bell bottom, air breaks the siphon - The grow bed refills, and the cycle repeats (typically every 15-20 minutes)
This flood-and-drain cycle provides roots with both water/nutrients and oxygen — essential for healthy plant growth.
Cycling the System
Before adding fish, you must establish the beneficial bacteria colony (this takes 4-6 weeks):
1. Fill the system with dechlorinated water 2. Add a source of ammonia (pure ammonia liquid, 2-4 PPM, or a few hardy fish) 3. Test water daily for ammonia, nitrites, and nitrates 4. When ammonia and nitrites read zero and nitrates are present, the system is cycled 5. Now you can safely add your full fish stock
Fish Stocking Guidelines
For a 180-200 gallon fish tank: - Tilapia: 20-30 fish (warm climates or heated systems only — they need 70°F+) - Goldfish/Koi: 10-15 fish (cold-hardy, great for beginners) - Channel catfish: 5-8 fish (excellent eating, tolerant of conditions) - Bluegill: 15-20 fish (native to Missouri, very hardy)
General rule: 1 pound of fish per 5-10 gallons of water once fully grown.
Plant Selection
Almost any vegetable grows well in aquaponics. Best performers in IBC systems: - Leafy greens (lettuce, kale, Swiss chard, spinach) - Herbs (basil, mint, cilantro, parsley) - Tomatoes and peppers (need mature, well-stocked systems) - Cucumbers and beans (need trellising above the grow bed) - Strawberries
Maintenance Schedule
- **Daily:** Feed fish, check pump operation, visual inspection
- **Weekly:** Test water parameters (pH, ammonia, nitrites, nitrates), remove dead leaves
- **Monthly:** Clean pump intake screen, check air stones, prune plants
- **Seasonally:** Deep clean pump, replace air stones, adjust fish feeding for temperature
Cost Breakdown
- Used IBC tote: $75-150
- Pump and air pump: $60-100
- PVC plumbing and bell siphon: $40-60
- Clay pellets (4-5 cu ft): $80-120
- Fish stock: $20-50
- Miscellaneous (silicone, fittings, test kit): $40-60
Total: approximately $315-540 for a system that can produce 100-200 lbs of vegetables and 20-40 lbs of fish per year once established.