Velda maintains a maximum capacity for the Cross Flow Biofill so that too much pressure does not build 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 outlet must not be reduced to a smaller diameter
• the water should not be 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.