i have been lurking on the board for a while and first wanted to say thank you for all the incredible info. now to my questions: this is our 2nd summer with the pool but we had to get a new liner put in and also added a swg. as soon as it was done around memorial day, we went out of town for a week and didn't have time to buy all of the proper chemicals to add beforehand. i decided to just put the swg on 60% and take care of it when we get back. long story short, when i got home the pool was sparkling. i tested my water, followed the advice of the stickies on here and got all of my chemicals. i added the cya yesterday and will test it again in a week or so. my readings before i added the cya were:
CC less than 0.5
CYA 0 (before i added it)
Calcium Hardness 150
my 2 questions are this: how could i not have had any algae pop up with a fc reading so low (and is it common to have such low FC and CC at the same time)? i have tested many times the last few days to make sure these were accurate.
and the second question i have is how do you know for sure if you have algae besides the obvious? my water is clear and sparkling but i have noticed some dirt-like substances in certain spots in the pool. i have brushed them and also run the aquabot, they clear up, but then come back in the same spots. how do you tell the difference between dirt and algae especially when your water looks good?
thank you in advance for your responses.