I had an issue with algae about two months ago. Getting the Taylor kit and following recommendations on this thread I have set my SWG to 50% capacity. The last two tests have shown that FC is around 4-4.5 ppm, with CYA levels around 70-80 ppm, and CC has always been quite low (0.5 ppm or less)
I checked the pool this morning and I could see small patches of algae forming. The pool is not sparkling clean as we have had some high winds over the last couple of days and sand has blown in, but it is clean enough. Furthermore, the pool has not been used for at least 4 days now (we've been travelling).
I have only noticed it this morning. I decided not to do anything about it just yet because I first want to confirm this is really algae (sometime it's easy to confuse with sand), but it does look like it as sand can not stick to the side of the walls
Being that my chemistry seems to be right, what could be the cause of the algae forming?
PS - it's been a while since I last backwashed (I'd say 6 weeks or so), nevertheless the pressure on the sand filter is still relatively low. Could it be that algae is forming inside the sand filter which effects the rest of the pool, and that's even though FC level is right?