I have had my pool open all Summer and haven't had any issues what so ever. I follow the BBB method to a "T" and everything has been great. Last night I noticed just a small amount of green growing on the walls and floor of my pool in several different spots. First time ever. It brushed right off very easily. It was definitely greenish in color. After brushing, I gave the entire pool a good vacuum. The water was and is still crystal clear. But this has me a little concerned because I haven't seen this situation at all with my pool the entire time it has been open all year.
The only thing I have been doing different is that I recently raised the CYA up slightly. It was at about 30. It's now at roughly 45/50. I was still targeting 5 ppm for chlorine even with the new CYA reading. Should I raise my chlorine target up to 6 ppm or possibly higher given the new CYA reading and recent algae issue and just leave maintain that target the rest of the Summer to prevent any further outbreaks?
Last nights test results were as follows.
FC - 2.5
pH - 7.4
TA - 50
CYA - Between 40 and 50
CC - 0
I'm thinking the FC at 2.5 might have been a little low given my new CYA reading and perhaps that's what allowed the algae to begin to grow.
Pool calculator told me to add 111 oz of bleach but I put in a full gallon (128 oz) because I was a little (to say the least) paranoid when I saw the green slime on my pool walls.