Two weeks ago, we came back from a half term break to find this.
So some chlorine shock, later it was looking like this.
Which the eagle-eyed of you will see is still a bit cloudy. Some “floc” and vaccing later and it’s crystal clear again. Picture of that, as proof(!), to follow. It was my first proper ‘floc’ effort. I used HTH RapidFloc liquid, which seemed to be extremely effective. It required a bit of care to vacuum up the ‘sediment’, but because I was pumping to waste rather than through the filter the water came up super-clear really quickly.