EHEIM LOOPpro pond filter with pre-filter, pump and UV-C

The 26000 and 38000 models carry exactly the same pump, a FLOW6500 that delivers 6,200 litres per hour at 70 watts, in the same tank. What sets them apart is the clarifier: its tube is 36 watts on the first and 60 watts on the second. Going from the 26000 to the 38000 therefore increases the treatment power against suspended algae, not the flow rate or the filtration. The choice between the two depends on how much sun your pond gets as much as on its volume, since water in full sun encourages algae more than shaded water.

The six models come in three tank formats, which lets you plan the space beside the water. The 6000 fits in a tank measuring 525 x 435 mm and 290 mm high, the 8000 and 12000 in the same base at 380 mm high, the 18000 in a tank measuring 750 x 640 mm and 335 mm high, and the two largest in that base at 435 mm high. The first three models connect with a 3/4 inch fitting, the next three with a 1 inch fitting. The pump changes too: PLAY1500 on the 6000, then FLOW2500, FLOW3500 and FLOW5000, and FLOW6500 on the two largest, with a delivery head that rises from 1.4 to 3.6 metres. The pump cable is 10 metres long and the clarifier cable is 5 metres long.

The biological chamber is also what links a pond to a crop. The bacteria in it convert the ammonia from the fish into nitrite, then into nitrate, and this nitrate stays in the water until something consumes it. Plants installed on the filter return play that role and close the cycle, provided that the flow passing through them remains compatible with the pump of the chosen model. A spiral pipe connected to the tank outlet can carry part of the return to a grow bed placed lower than the tank, with the water then flowing back into the pond. The guide to the nitrogen cycle in aquaponics helps you follow these stages by testing.

The clarifier in each kit is a Clear UVC, and its tube wears out while the rest of the unit stays intact. The replacement UV-C bulb for Clear UVC is ordered in the wattage of your model: 9 W for the 6000, 11 W for the 8000 and 18 W for the 12000, then 24, 36 and 60 W for the three largest. The tube should be replaced after 8,000 hours of service, even if it still lights, as its germicidal output has by then dropped considerably. As frost approaches, drain the pump, the clarifier and the tank, clean them and store them under cover, since water trapped in a unit can split it when it freezes. The spring restart is then a bit like a small commissioning, while the bacteria in the biological chamber re-establish themselves.