There is no FC because I assume the AquaRite stop working at certain degree (actually, to confirm, I SuperChlorined for 24hrs and still no FC). PH is very low, which is rare and I think because of the rain, too. Salt is also low because of the rain but that shouldn't matter since the Aquarite isn't making any Chlorine. I added Algaecide 60+ and generally it works really well but not this time. Also added Phoslow to make sure Phosphate is not too high. Pump runs about 5-6 hrs a day like last winter. What can be the cause? I didn't think algae can live/grow in cold water. Haven't got a chance to check the water with the store yet.
Oh, the water is clear, just some parts of the wall/steps.