If a chlorinator lid begins to leak there are a couple of things to check.
First. check the o-ring, and the top of the canister where the top screws on to make sure it is clean and not gunked up, or out of place, or broken.
Next, check the screw just underneath the black cap at the top. If there are issues and you can tighten them up, or use Magic Lube on the o-Ring to reseal, great. If not – you will either want to replace the lid assembly, or in some cases if the unit is old, replace the entire unit!
If your chlorinator gunks up or loses flow it could be from chlorine tablets that have too many fillers in them. We recommend purchasing your chlorine tablets from a pool store – not a big box retailer. The retailers sometimes have quality control issues with tablets coming in from overseas with too many fillers which can cause chlorinator and filter issues. When in doubt, buy from a pool place!