I only use ball valves where they are absolutely necessary since they too need to be kept free from build ups if they are going to work properly. The only pumps that have ball valves are my closed loop pumps (the ball valves are not visible in the pics). The remaining pumps (which pull from the sump) can be serviced two ways......1) I can unplug the pump needing service, reach into the sump and screw a pvc plug into the threaded bulkhead, and then remove the pump.....or what I do most often 2) I wait until water change time (once a month) where the sump gets completely drained and cleaned out. I keep spare pumps that are exchanged for the fouled pumps at this time.....I then clean/rebuild the fouled pump which will replace another fouled pump in the future. All reactors do have ball valves to enable removal of the equipment without turning off the main tank pumps.
Al my pumps are sequence 1000 series.