Aquaponic kit with vertical towers for greenhouse

The kit weighs 75 kg when delivered and 550 kg in operation. This difference is the only real surprise the product holds, and it comes from the pond and the water-saturated grow medium. In a greenhouse placed on bare earth or a concrete slab, this raises no issues. On a wooden floor, a timber decking terrace, or a raised structure, ask yourself the question before ordering rather than after filling up. Once in water, the whole system cannot be moved without draining it first, so the positioning within the greenhouse is decided at the time of assembly, keeping a clear walkway and access to the pond. Also bear in mind the shade cast by the towers: a tall column puts the ground behind it in shade for part of the day, which affects what you can still grow in the soil alongside it.

Assembly takes a single day, working independently, and requires common tools: a cordless drill-driver, wood and metal drill bits, a 10 mm spanner, a craft knife, a screwdriver, and a heat gun. That's the only list worth reading before you order, because the heat gun is the one tool not everyone has in their garage. Once assembled, maintenance amounts to around 30 minutes per week, split between feeding, topping up the water, and reading the test results. Plan for two people on assembly day, as setting up the towers and the pond is considerably easier with a second pair of hands. Allow a further half-day for filling and adjusting the flow rate, a process carried out with plain water and no fish in the pond whatsoever.

This is the stage everyone wants to skip, and it is the one that determines how your first year goes. A new system contains no nitrifying bacteria, and without them the ammonia produced by the fish never becomes a nutrient. You need to fill the system with water, seed it with the supplied bacteria, and wait three to four weeks before introducing any fish. The test kit included is there for exactly that purpose: it tells you when the water is ready, and no date marked on a calendar can replace it. Introducing fish too early means losing them and starting over. During those three weeks, you stock the towers, adjust the flow rate, and get into the habit of reading a test, so that by the day the fish arrive, you already know how to run the system. The sequence is always the same and is clearly visible in the readings: first a peak in ammonium, then a peak in nitrite, then both dropping back to zero as nitrate appears. Aim for a reading every 2 days during this period, and write the values down rather than simply looking at them.

Once the system is up and running, it grows with you. If your headroom allows, extension modules stack onto the existing towers and add another tier of growing slots without taking up any extra floor space. And for vegetables the towers cannot support, tomatoes, courgettes, or aubergines, large-plant beds connect to the same water circuit. Neither addition needs to be decided on day one; they are chosen after a season, once you know what you are actually growing and what you are missing. Every increase in growing slots also requires a corresponding increase in fish stocking, otherwise the nutrition is spread across more plants without actually increasing. Leave a few weeks between one extension and the next, to give the bacterial colony time to adjust to the new load.

The kit ships in 4 to 6 parcels of 20 to 30 kg, making it deliverable by a standard courier with no specialist vehicle or tail lift required. This is a direct result of how it is designed: because it does not include a greenhouse, there is no structure to transport. You can therefore have it delivered to a town house and carry it to the far end of the garden without any heavy lifting. It is also what makes it easy to move, the towers dismantle and come with you if you relocate, which is something a glazed greenhouse cannot offer. Simply check that the delivery address can accept several parcels on the same day, and plan to store them somewhere dry while you wait for your installation day.

Once the system is up and running, three values are enough to keep it in check, and they are all read from the pond. Ammonium and nitrite levels must remain undetectable; any positive reading signals a colony overwhelmed by feeding or by an unnoticed dead fish. pH should be kept between 6.8 and 7.2, a compromise between the needs of the fish, the nitrifying bacteria and the plants. Correct it gradually rather than all at once, as a sudden swing causes more harm to the fish than a value slightly off the ideal. Top up evaporation with plain water, leaving it to stand or filtering it if it is chlorinated, since adding chlorinated water directly affects the bacterial colony before it even troubles the fish. In winter, reduce feeding as the fish slow down, since uneaten food breaks down and loads the water with nutrients at precisely the time the bacterial colony is least active.