TECO TK chiller, aquarium and aquaponics, 150 to 6,000 L

Above 2,000 litres, the TK3000 and TK6000 take over for a large pond, a holding tank or a production aquaponic system. They cool up to 3,000 and 6,000 litres of water kept at 25 °C in a room at 30 °C. The lower the set temperature, the smaller the volume they can handle: the TK3000 can still maintain 500 litres at 8 °C. Their thermostat can be set from 8 to 30 °C. They draw 750 and 900 W when cooling, and they require an actual flow rate of 3,000 to 4,000 L/h, which you provide with a pump that you will need to supply separately. Water enters and leaves through 25 mm fittings. The casing measures 39.5 x 60 x 56.5 cm and weighs around 40 kg, and it is fitted with castors. Both models are cooling only; you can add a heating element and a UV-C steriliser as options.

The TK2000L, known as the Lobster, is designed to work at low temperatures. You set its target from 5 to 15 °C, the range for lobster holding tanks, cold-water crustaceans and species that live in very cool water. In a room at 30 °C, it keeps 600 litres of water at 8 °C or 1,400 litres at 15 °C. It draws 480 W when cooling, needs a flow of 500 to 800 L/h and connects with a 16 mm fitting. Its 31 x 31 x 50 cm casing weighs 24.9 kg, and it operates in a room between 10 and 38 °C.

The TK150 to TK2000H units are fitted in line on the circuit, after the filter, with a flow rate of 300 to 500 L/h for the TK150 and 500 to 800 L/h for the H models. The connectors, clamps and reducers are supplied. Install your unit in a well-ventilated spot, never in a closed cabinet: the heat removed from the water must be able to escape. Clean the air filter on the front panel at least once a month, because a clogged exchanger runs for longer and uses more power. A filter upstream prevents waste from settling in the exchanger.

On receipt, leave the unit standing upright for several hours before switching it on, so that the refrigerant and the compressor oil settle. Fill the circuit and check there are no leaks before plugging it in: it must never run without water circulating. If the room might freeze in winter, drain the heat exchanger. In a small closed room, the air heats up and efficiency drops; ventilation, or installing the unit in a neighbouring room with longer pipes, solves the problem.

Three accessories are offered on this page, because they are only used with these units. The 300 W heating kit fits a TK500, TK1000 or TK2000 supplied without heating: once fitted, the thermostat's o1 parameter activates the element, and the unit heats in winter just like an H model. The 18 W UV-C tube replaces the lamp of a TK3000 or TK6000 fitted with its UV-C steriliser. The TECOnnect Wi-Fi module links your TK500H, TK1000H or TK2000H to the app, so that you can monitor and adjust the temperature remotely.

In Europe, the water temperature of an aquaponic system follows that of the air through the seasons. An above-ground tank set up in a greenhouse can thus exceed 25 °C in the height of summer, then drop below 10 °C in winter. Yet each fish species tolerates only a relatively narrow temperature range, as explained in the article on choosing fish for aquaponics. A TECO chiller keeps the water at the right temperature during the summer, while the H models, or a model fitted with the heating kit, also provide heating during the winter.

Salmoponics, that is, the rearing of salmonids in aquaponics (trout, salmon, char, grayling), is hardly feasible without cooling. These fish are poikilothermic: their body temperature, and therefore their metabolism, follows that of the water. Rainbow trout, the most widely farmed species in aquaculture, grow best between 13 and 18 °C. Above 20 °C, it feeds less well and shows signs of stress, and its lethal temperature is around 25 °C. Fish such as brown trout or brook char are even more sensitive to heat and cannot tolerate water above 16 °C.

The main danger comes from dissolved oxygen. The warmer the water gets, the less of it the water can hold: at saturation, fresh water contains roughly 10.1 mg/L at 15 °C, 9.1 mg/L at 20 °C and only 8.3 mg/L at 25 °C. At the same time, the oxygen consumption of the fish rises, as does that of the bacteria in the filter. Salmonids need at least 8 mg/L to breathe without difficulty, and they begin to gasp below 6 mg/L. In a heavily stocked pond, a single heatwave day can therefore wipe out the entire stock, and with it several months of growing on. This is why a chiller is sized for the hottest day of the summer, not for an average day. The guide to maintaining an aquaponic system in summer details the other precautions to take during hot spells.

With tropical fish, the constraint is reversed and it is winter that causes the problem. Tilapia grow best in water at 27 to 30 °C; they stop feeding below 17 °C and die below 12 °C. The TK500H, TK1000H and TK2000H include a 300 W heating element, which the heating kit allows you to add to a TK500, TK1000 or TK2000 that does not have one. The same unit then holds the chosen temperature all year round: cool for salmonids, warm for tilapia.