Solar-powered automatic feeder for ponds, 6 L reservoir

Programming is done with a screen and four buttons: SET, two arrows and RUN. You set the time, then up to 6 feeding slots per day, each with its own duration of up to 20 seconds. The RUN button triggers a dispense on demand, which is useful for calibrating the unit: collect what comes out in a tray during one dispense, weigh it, and you know the quantity actually delivered for the duration you have set. The daily ration is then divided across the number of meals you have chosen. Repeat this weighing if you change pellet size, because a 2 mm pellet and a 6 mm pellet do not flow at the same rate.

Your device accepts pellets of 2 to 9 mm, which covers the usual sizes of pond fish feed. At the bottom of the hopper, a rotating wire turns during dispensing to stop the pellets from blocking the outlet, and a compartment under the lid takes a desiccant sachet that limits humidity in the reserve. Use only dry feed, never sticks, which take up moisture again, and clean the hopper every 4 to 6 weeks. A 6-litre hopper left unchecked for a whole summer ends up containing lumps rather than pellets: empty it, wipe it out, let it dry, then refill with fresh feed rather than topping up over an old layer at the bottom. While you are at it, look at the outlet flap, where a swollen pellet sometimes gets stuck and blocks the ones behind it.

The installation height matters as much as the orientation: too low, and the spray falls flat close to the unit; too high, and the wind carries it away. The dispenser stands on feet that are secured to the lawn or the soil with pegs, which holds it in place at the edge of a pond with no coping; on a terrace or a hard coping, place it flat and steady. It is rated IP44, meaning it is protected against water splashes from all directions, and therefore against rain, but not against immersion. Do a dry run before filling the 6 litres, since the unit weighs 4.8 kg when empty and considerably more once full.

On a pond connected to grow beds, the feeding rhythm is the first adjustment you have, since it sets the amount of nitrogen entering the system each day. The 6 time slots let you split this input rather than concentrate it in a single meal, and cut it back sharply as soon as the water cools. A load spread over the day gives the bacteria time to process it, whereas one large daily meal produces a spike of ammonium that the biofilter takes several hours to absorb. To size the ration, aquaponics works in grams of feed per square metre of growing area: about 40 to 50 g per day per square metre for leafy vegetables, more for fruiting vegetables. Your fish's appetite follows the water temperature, a subject covered in the winter feeding guide, and a floating thermometer within sight helps you decide.