When I start the high flow jets I hear a klunk noise and get a low flow from the jets. After several tries I get a fast normal flow with no klunk. The only thing between the pump and jets is a 2" check valve. Could this cause this problem? Do I need this valve, it only seems to keep flow from the circulation pump from flowing into the jet pump ?

Thanks,
John

Hi John,
It sounds as though the paddle within the swing valve has broken off. ( it is held in place by a neoprene rubber material that also serves as a seal ).
The inconsistant blockage occours as the valve plate becomes lodged sideways, and dead on, as it bobs around in the valve body. ( kinda like Russian Roulette) It is an important part within the spa as it serves to allow the suction side of the filtering circuit to come from the foot well main drains, and not the jets. The booster pump, and circ pump probably share the same heater/ filter circuit, therefore the need to isolate the circ pump suction.
You will need to cut out, and re-cement the offending valve. Do not bypass.

Thanks,
I'll pick up a replacement.

john