I am getting ready to replumb my filter pad. Currently I have no unions on my pumps and no service ball valves or check valves in my pump setup. I think I am defiantly going to use 2" unions on the pump but it would be nice when doing maintenance on the the filter or pump to be able to prevent all the water in my lines to drain back into the pool when I'm doing it. Been looking at spring check valves, does anybody have any experience with them? I'm afraid I might leave a ball valve closed by accident and starve a pump. Any comments would be appreciated.