make sure you brush around fixtures, and inside and around your light niche
That's a lot of chlorine!! Maybe you had an ammonia problem to start with...Started Saturday so day 5.. gone through almost 50L...gonna keep powering on...
We swam several times at FC > 30, but I have a pH meter so I'd been adjusting the pH periodically to keep it in a sensible range.
Large doses of liquid chlorine with a high CYA pushed my pH up toward 9, so it can and does happen. It'll come back down as the FC level falls, but I acid dosed to keep it under 7.8.