CultiMate 4-Pack hydroponic kit, 4 pots and shared reservoir

Because the four pots are connected to the reservoir, you make up a single solution, measure a single pH and fill a single reservoir. The float valve then maintains the shared level mechanically, reopening the inlet as soon as it drops. The trade-off is that all four plants receive the same solution, so they must be at the same stage and have the same needs. The controller acts here as the single measuring point, and its level tube replaces the four readings that a set of independent pots would require.

Maintenance then comes down to three tasks a week. You read the level tube on the control pot, which shows the state of the whole network, and you top up the reserve. You measure the pH at the same spot, since the five linked containers communicate and give the same sample, and you correct towards 5.8 to 6.2, letting the circulation mix for an hour before testing again. Every 2 to 3 weeks, you replace the whole solution rather than topping up indefinitely: 120 litres become unbalanced just as surely as 15, only more slowly. This is the chance to rinse the strainers on the five columns and the float of the valve. A logbook, even a basic one, makes these readings far more useful, because the change in pH over 3 weeks signals what a single measurement cannot. Water consumption is tracked in the same way: a gradual rise simply goes with the growth of the plants, whereas a sudden drop means checking the condition of the roots before blaming the weather.

Choosing the spot comes before the first fill, as the full system weighs around 150 kg once the wet grow medium is counted. It needs a level floor that can bear the weight of the water, and enough clearance to walk around the four pots without moving anything. All five containers must sit at exactly the same level, to the millimetre, because gravity alone equalises the water heights between them. A slab, a load-bearing floor or a tiled surface will do; a board set on trestles, much less so. Once the pots are spaced out around the reservoir, leave a clear passage on at least one side as well. Finally, allow 10 litres of clay pebbles, graded 8 to 20 mm, for each growing chamber, rinsed until the water runs clear, and four plants that are already rooted, all at the same stage.

Medium-sized plants grown together make the most of these four 15 L pots, whether that is four basil plants, four chilli peppers, four strawberry plants or four lettuces. For tomatoes at full size, the 45 L reservoir shared between four empties quickly in summer: the 45 L pot used individually is then more comfortable. The guide what to grow in hydroponics gives the cycles species by species. A good rule is to choose four varieties of the same species rather than four different species, so that light, nitrogen and staking height requirements stay comparable from one pot to the next.

The bodies of this system are rotationally moulded in France from recycled polyethylene, and treated against light and ultraviolet. These bodies are guaranteed for life under normal use, and the air pump for 2 years. A wall that lets light through grows algae in the solution, and algae in a 120-litre system end up clogging all five pumping columns at once. The reservoir lid is solid and lifts at one side, which lets you fill and measure without dismantling anything, or exposing the solution to light for more than a few seconds. Rotational moulding also gives walls in a single piece, with no weld or glued corner, in the places where an assembled tank eventually seeps. Polyethylene is cleaned with clean water and a sponge between crops; avoid detergents, whose residues would pass into the next solution. A whitish limescale deposit at the waterline comes off with diluted white vinegar.

The pump is the only active part of the kit, so its condition affects all four crops at once. Its diaphragms wear with the hours of continuous running: circulation then weakens in all five columns together, which sets it apart from a blocked strainer, which affects only one pot. Place it above the water level, otherwise a power cut will make the solution flow back up the air pipe by siphoning. A non-return valve fitted on the air pipe removes this risk. Finally, check that the splitter tees are not pinched behind a pot, as a single crushed section is enough to starve a column of air without anything else changing.

The network is made up of just a few parts, and each one can be replaced individually. The pots are connected to the reservoir by black tubes of 18 x 23 mm, two of 60 cm and three of 40 cm, distributed by five tees. On the controller side, two 16 mm barbed connectors and a 90° elbow join the 15 x 17.5 mm tubes. Each pot keeps its own distribution ring, pump column and strainer, the same as on the 15 L pot sold separately. If a fitting cracks, the 16 mm barbed connectors and elbows can be ordered in packs, without buying the kit again, and you can have the network back up and running within the day.