Tower extension modules for the MyFarm kit

Adding planting positions changes the balance of the system, because the nutrition comes from the fish and their number has not changed. The nitrogen available depends on the feed given each day, and the same input is now shared across 12 to 36 more plants. You have two options, and they can be combined. The first is to increase the feed ration gradually, and if necessary the fish stocking, in steps of a few weeks, giving the biofilter time to keep up. The second is to choose undemanding crops for the new positions, such as salad leaves and herbs, rather than fruiting plants. Pale young leaves or plants that stall point to a shortfall, showing a few days after the nitrate test does.

The modules slot onto the existing towers thanks to the notches in their collar, without altering your installation: the water that already circulated in the tower simply passes through one more tier before returning to the pond. You have no plumbing to rework and no pump to replace, and a pack is fitted tower by tower, stopping the circulation for no longer than it takes to slot in each module. After fitting, check the flow at the top of the tower, as the water should reach the new top pot as freely as the earlier ones; if it does not, clean the pump filter, which fine particles of grow medium eventually clog. Take the opportunity to rinse the existing modules while they are accessible, and fill the new pots with clay pebbles of 8 to 16 mm grade, like the original ones.

You maintain a taller tower like any other, with one extra step. Once a year, empty the towers and clear the modules of dead roots, which would otherwise end up slowing the flow of water from one pot to the next. Food-grade plastic is cleaned with clean water, without any detergent that would leave a film in contact with the fish water. To reach the new tier, provide a stable step stool, safer than an upturned bucket on a greenhouse floor that is often wet. The guide to maintaining a growing tower details drops in flow and how to fix them.

Order the pack that matches your actual height, not the one you hope for, since all twelve towers in a kit gain the same number of tiers. If you are torn between two sizes, remember that the top modules are the brightest but also the hardest to reach: one tier fewer lets you work comfortably. The modules can also happily wait from one season to the next; there is nothing to stop you starting with 12 modules, seeing how your pond copes, then adding more the following year. The crops that suit the towers are the same on every tier: leafy vegetables, herbs, strawberries and small fruiting vegetables, while larger plants are better placed in grow beds for large plants.