Yep. What Janet said! I'm sure those couple of days where your cl dropped are the culprit. With a cya of 35, you have to keep the cl level between 3-6 ALL the time or it is an invitation to algae! Lotsa bleach and filtering 24/7 are what you need to do now to clear it.

I just modded your latest post in and got a chuckle from it!