Here´s a short description of the technique involved in setting up the 500 liter tank.
The main tank is 500 liters, from here the water is guided to a 250 liter sump through the overflow. From the sump the water is pumped to a 140 liter aquarium, which was my old freshwater stream aquarium, now functioning as a filter.
Skimmer: DYI “mean midget” rated for 1000-1500 liter, airflow approx 3000 l./h. with a Atman HP8000
Flow in main tank: 1 X 12.000 l./h, 1 X 6000 l./h and 1 X 2600 l./h – all Tunze – the pumps are on timer, reversing the flow every 12 hours
Pump from sump: 2000 l./h Aqua-bee
Chiller: Resun 15R it is rated for a smaller aquarium, but with the thermoglass and insulation with styrofoam I hope it is enough. In addition I can ventilate the whole room by drawing in fresh cold air through a ventilation fan in the outer wall and there is a fan in the ceiling drawing out the hot air in the room through the roof.