Hi Everyone, I'm a newbie here. Although I've owned an 18 foot above ground pool for 7 years, I'm seeing something for the first time. I have opened my pool about 2 weeks ago (on Long Island, NY). It took the usual 5 days or so to get the chem levels right and all was good. My first couple of weeks I like to clean the filter cartridge once a week after vacuuming. Yesterday I noticed that the cartridge had a pretty green tint that washed off easily with a garden hose. There is not a sign of algae in the pool and the water sparkles. I was wondering if maybe one of the chemicals may cause this, or should i worry that I have some 'invisible' algae? Thanks much for your time.

Mike