Planted Tank Guru
Join Date: Jan 2010
Location: Contra Costa CA
Here are 4 ways to reduce the pressure at the intake yet still have lots of flow:
Put a large sponge over the intake. The larger the surface area of the sponge the less pressure per square inch might be holding the fish stuck to the sponge. Use a piece of PVC that is drilled full of holes inside the sponge. 1" PVC, a foot long, with LOTS of 1/4" diameter holes.
You could also split the intake into several parts, and put sponges over each part. You can do this with PVC Tees and other fittings. For 1000gph I would use at least 1" PVC for each intake, and they might all come together into 1-1/4" pipe (depends on how the pump is plumbed, and the layout of pipe inside the pond)
Another way to make this work is to make the intake of a piece of PVC that is drilled full of holes and bury the intake in the gravel (if it is gravel).
The fourth possibility is to screen off part of the pond with some screening and put a sheet of foam there. Then the intake is behind the foam.