Any help would be greatly appreciated.

Thanks for the tip. My pressure is currently at 60 psi. What should I shoot for?

i'll assume you are using pop-up spray heads which run best at 30psi so you should shoot for about 33 to 35 psi at the valves.

Thanks. I am using pop ups. Any recommendations on a reducer? I assume that cutting it in right below the ball valve would be ok?

I guess I could test the hammer reduction by reducing the pressure by closing the ball valve. Yes?

sorry it has taken so long to reply. internet was down for a couple days. a standard reducer from any sprinkler supply store will work good right below the ball valve. partialy closing the ball valve will decrease the volume of water but increase it's velocity and actualy make the water hammer worse.

Hmmm. I'd appreciate the education here. Can you explain the statement above - partialy closing the ball valve will decrease the volume of water but increase it's velocity and actualy make the water hammer worse.

what happens is your trying to move a volume of water at a certain psi through a smaller connection which will lower it's psi thru friction loss but will increase it's velocity thru that same pipe. so what happens is the water hits the fittings or valve at a higher speed causing the hammer to be stronger.

Got it. Thanks.

Any recommendation on an inexpensive pressure reducing valve that I can cut into the PVC pipe?

i don't have any specific recamendations, but any irrigation supply house or evan home depot can supply you with one that will work.

J, My $0.02 is If the problem still exists after lowering the pressure, you should brace your manifold. It is located between two flexible pvc pipes with no ability to withstand the reaction force produced by rapid change (velocity from valve closing) in water movement or direction (water hammer).