You were spot on. Now i bought the poollab 1.0 tester, and a test showed
PH: 7,7
FC : 1,22
TC: 1,28
TA : 118
CYA : 6
So - my CYA is way too low, which is probably why my chlorine wanish Way too fast - and thus algae in the morning.
i Will add some CYA (stabilizer) to protect the chlorine...