Water Circulation

The general guideline for water turnover is 5 times the tank volume per hour for unplanted or lightly planted, and 10 time the tank volume per hour for heavily planted.
So with your tank, 2500 litres/hour if you have few or no plants or 5000 litres/hour if you are heavily planted. But this needn't be all from the filter. You can use powerheads to add water movement if you think a lower rated filter will hold enough bacteria for the fish you want.