Description
Turn an established pond into an aquaponic vegetable bed
The FishPlant Retro-Fit Grow Bed Unit lets you run a FishPlant-style aquaponics bed straight off a pond you already have, with no separate fish tank to buy. A submersible pump lifts pond water into a black FishPlant PlantBed filled with clay pebbles; the water trickles through the pebbles and returns to the pond through the drain and overflow fittings. On the way, beneficial bacteria living on the pebbles convert fish waste into the nitrate plants feed on, so the bed grows salads and herbs while the plants take nutrients out of the pond water.
What's Included
- FishPlant PlantBed (grow bed)
- Inlet/drain fitting
- Overflow fitting and tubing
- FishPlant PlantBed Pebbles (clay pebbles)
- Submersible pump
Key Benefits
- Uses the pond you already have – no fish tank, stand or plumbing kit to source separately.
- Fish feed the plants – bacteria in the pebble bed turn fish waste into plant-available nitrogen.
- Plants help the pond – roots draw nutrients out of the water as it passes through the bed.
- Clay pebble media – free-draining, reusable and inert, giving good air around the roots.
- Complete kit – bed, pump, fittings, tubing and pebbles in one box.
Why grow beds struggle without the right flow
Fish waste is mostly ammonia, which is toxic to fish and useless to plants until bacteria convert it. A bed of clay pebbles gives those bacteria a huge surface to colonise, and constant flow keeps oxygen moving through the root zone so roots stay healthy rather than sitting in stagnant water. FishPlant's guidance is to let a new bed run for at least a week before planting, start with salads, leafy vegetables and herbs, and add plants gradually as the bacteria establish.
How to Use
- Site the bed on a firm, level base beside the pond so water drains back into it; no stand is supplied.
- Fill the PlantBed with the clay pebbles, place the pump in the pond and connect the tubing to the inlet, drain and overflow fittings.
- Run it for at least a week before planting so bacteria colonise the pebbles; aim for a pH of 6–8.
- Plant well-rooted plugs just below the pebble surface. FishPlant warn never to use stonewool, as its fibres can harm fish gills.
- Use physical pest control only – systemic pesticides are toxic to fish.
- Clean the pump monthly and keep the inlet clear of debris.
Technical Specifications
- System type: aquaponic media grow bed run from an existing pond
- Contents: PlantBed, inlet/drain fitting, overflow fitting and tubing, clay pebbles, submersible pump
- Grow media: FishPlant PlantBed Pebbles (expanded clay)
- Working pH: 6–8 (FishPlant guidance)
- Feed capacity: a mature PlantBed processes about 30 g of fish food a day (FishPlant guide)
- Suggested crops: salads, leafy vegetables and herbs
- Not included: stand, pond, fish, heater or air pump
Frequently Asked Questions
Do I need a fish tank?
No. The Retro-Fit unit is designed to run off an established pond: the pump sits in the pond and the bed drains back into it.
Do I need to add nutrients?
Fish waste supplies most of what the plants need. FishPlant's guide says iron usually needs adding in a fish-safe form, and calcium may be needed in very soft water.
What should I plant first?
Start with salads, leafy vegetables and herbs from well-rooted plugs or washed bare roots, and avoid stonewool plugs. More demanding crops can follow once the bed is established.
Is a stand included?
No. The kit contents are the bed, pump, fittings, tubing and pebbles, so plan a firm, level base that lets the bed drain back into the pond.
Works Well With
