Filter Cartridge is green but pool water sparkles, should I worry?

[MichaelC22]

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

[Watermom]

What are all the chemicals you have used? Anything with copper in it?

[PoolDoc]

"Should you worry?" Yes.

Green on filters is often either algae (not good) or copper (not good, either). You can find out by getting some bleach, some Vitamin C tabs, a couple of clear wine glasses, and some green sludge off your filter. Put a bit of the sludge in each glass, then add bleach to one. Add tap water + Vit. C to the other. If it's algae, the bleach will turn it brown. If it's copper, the Vit. C will cause the color to disappear or at least change.

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