I have a 15' round AGP with a new-to-me Waterways cartridge filter. Right now, the hose runs right from my skimmer box into my Hayward pump, then directly into the filter, then out to a single return. There are no shutoff valves anywhere, so when I need to clean the cartridge or do anything with the pump or filter I must disconnect the skimmer box hose at the pump and hold it above the water line. Obviously it'd be much easier to have a valve somewhere. But being new to this setup and unable to find a picture of a shutoff valve, I'm not sure what to do.
FWIW, all of my lines are flexible tubing, connecting using hose clamps.