How do I fix a bleeder valve that sprays constantly?

Start by tightening the bleeder by hand — don’t use a wrench, or you’ll crack the plastic. If that stops the spray, you’re done. If not, replace the O-ring (a couple bucks at a pool supply store). If it still sprays, the valve body is cracked — replace the entire bleeder assembly. Also check the filter tank lid O-ring for a separate leak.