"bk" wrote in message
...
Trying to increase the flow from the filter back tot he pond. Increased return
pipe by 1/4" diameter. The filter is a canister type tetra PF3. Currently the
disarge pipe in about 8-10" below the water surface. Can this slow the flow
rate?

It will have an affect (even if only slightly, at the depth), because it is
placing a hydrostatic head on the pump that it has to overcome. Most pumps have
charts that come with them in the manual that tell you what the rated output is
for a given amount of head. At that depth, it should not have too great an
affect on the pump