When you have a grow bed full of gravel and you have some small children, one of the first things the kids are going to want to do is pick up some gravel and throw it in the fish tank. In itself this is not really a problem, but eventually some of the gravel is going to find it's way to your pump.
Yesterday, after a few days of the pipe blasting out of the pump, we installed some stainless steel screws to hold it on to the pump. During this process the pump got a clean and the non-return valve did too. Axl found about a cup of gravel above the n-r valve
blocking the spring.
It's amazing what a bit of cleaning out the pipes can do for a system
