Like many, my pump is too big and I have a sand filter, which doesn't filter much at all. I am using DE in my filter, and that helps, but I also installed a ball valve between my filter and pump. The intention here is to restrict flow and decrease the filter PSI, hopefully allowing it to filter better.

What I have found is it works well, and I have very precise control over the pressure and flow at the returns. I also have great control of my suction side auto pool vacuum, which tends to want to climb out of the pool and cause the pump to cavitate. I have noticed the filter actually capturing the finer dirt and silt that used to get pushed through before.

My question is can I cause damage doing this to the pump or something else? Is this a good idea? I have also considered replacing the pump impeller, but with this setup I have a lot of control, like a variable speed pump. Thoughts?