Tower extension modules for the MyFarm kit

The modules are made from UV-resistant food-grade plastic, the same quality as those in the original kit, and are white in colour. White reflects light back towards the plants rather than absorbing it, which matters all the more when taller towers cast shade on one another. The UV resistance prevents the plastic from cracking after a few seasons under glazing, where temperatures can spike and the radiation never lets up. These are two details you only notice after three years. Food-grade plastic can also be cleaned with plain water between crops, without detergent that would leave a residue in contact with the solution. A cracked module can be replaced individually, without disturbing the rest of the column or interrupting circulation for more than a few minutes.

Installation requires no tools, the modules clip onto the existing towers and all necessary fixings are included. There is no drilling, and no plumbing connections to redo: the water already circulating through the tower simply passes through one additional level before flowing back down. That is what makes this extension so easy to decide on after a first season, once you know exactly what you are growing and what you felt was missing. Do check the flow rate at the top of the tower after fitting: water should reach the new upper level just as freely as the previous ones; if not, the pump strainer needs rinsing. Allow about an hour to fit an extra level to all twelve towers including grow medium, and take the opportunity to clean the existing modules while they are accessible.

Adding growing slots shifts the system's balance, since nutrition comes from the fish and their number has not changed. There are two responses, and they can be combined. The first is to increase the fish load gradually, in stages spread several weeks apart, giving the bacterial colony time to catch up each time. The second is to choose low-demand crops for the new slots, lettuces and herbs rather than fruiting plants. Monitor nitrate levels in the weeks following the expansion: a reading that drops to zero indicates that the plants are consuming everything the pond produces. Pale young leaves or plants that stall tell you the same thing, a few days behind the test.

Order the pack that matches your actual height, not the one you are aiming for. An extra module cannot be stored usefully and cannot be fitted halfway. If your measurement falls between two sizes, choose the smaller pack, as it will leave you enough clearance to handle the plants on the top level without knocking into the glazing, which matters every time you harvest. Think too about how you will reach the new level, a stable step stool is far better than an upturned bucket in a greenhouse where the floor is often wet. The modules store without any difficulty from one season to the next, so there is nothing to stop you spreading the cost of fitting out the towers over two orders if your budget requires it.