Phloater wrote on 11/29/2005 9:40 PM:
I have seen on some hard PVC pipes
knobs to control the flow.

PVC ball valves are great for redirecting current. For
example when doing a water change I redirect the water
flow with ball valves and let the pump do the work, but
don't use valves on your pump to controle the amount of
water flow if you don't have to. Instead use a pump that
is rated for the flow that you need.

Wayne Sallee
Wayne's Pets