Ball valve on output or input to reduce flow?

[Soccer]

Hey all,

Just wondering where the best place is to but a ball valve in the pump plumbing to restrict flow. I am installing a maxijet externally and wanna be able to throttle it down if need be. I have one maxijet setup externally all ready, and the ball valve is on the input, however I am getting a lot of microbubbles. I was wondering if I should switch it to the output and it might help?

Anyways let me know whats best
Thanx in advance

[Tunjee]

Output should do the trick. By putting it on the input you will create cavitaion and therefore; bubbles.

[Fast Fred]

A ball valve is OK, but you'll have greater control with a gate valve.