In combination with the Cross-Flow Biofill we recommend the Green Line pump 5000 recommended. It has low energy consumption and long life.

If another pump is already present, we recommend the following:

Velda maintains a maximum capacity for the Cross-Flow Biofill so that too much pressure is not built up in the filter and the filter does not leak. Therefore, the following conditions apply:

• The water should be able to “freely” exit the filter.
• The drain should not be reduced to a smaller diameter.
• The water should not be raised (pumped up).

The net pumping capacity depends on the length and height of the pump to the filter. If the water has to travel a considerable distance and height, the net capacity will be a lot less.

If the pump has too much capacity, you can reduce it by installing a T-piece that allows some of the water to flow directly back into the pond. The amount of water can be regulated by the outlet diameter of this branch.