Posted by Janet Christian on September 11, 2005 at 08:26:37:
In Reply to: Re: Back flow preventers posted byJohn Chomko on September 10, 2005 at 14:37:39:
I doubt that you have a clogged swing/hinge/flapper style check valve. The likelihood with those is that they will get stuck in the open position if anything. They seem to be pretty reliable.
I expect that you used spring/plunger style check valves. These are designed for high-pressure systems (like those powered toilet flush systems). a pond pump is low pressure and will always have problems with a plunger check valve.
John has a good suggestion of first trying to blow it out but I'll be quite surprised if that turns out to be your problem. And if they are the plunger check valve you have no choice but to replace them with swing checks. Sorry.....