What IS this stuff? Algae, pollen, dead algae??

amy6152

Member
Apr 4, 2017
17
Rochester, NY
I need help determining what I'm dealing with. I have a greenish/yellowish substance collecting at the bottom of my pool (not the walls) in considerable quantities. I've been reading all the threads on mustard algae and pollen, so I know it doesn't sound like mustard algae - no difference in the shaded bit of the pool - distribution seems to follow normal circulation patterns. But it's definitely GREENISH YELLOW and I have a very hard time understanding how anything can be green at a SLAM level (19ppm, my CYA is 49). If it's pollen, I find that super strange, as we've never had anything like this in our pool in the four years we've had it. If you touch it with your foot, it disappears into a green poofy cloud. Something's alive in there, as I'm still burning through chlorine at around 7ppm/day. Would regular algae still be green on day three of a SLAM? That seems crazy to me. I vacuum and things seem better, then in the morning we're back to square one. What am I doing wrong? Should I vacuum to waste?

FAS-DPD test kit
16k gallon pool
ph 7.2
sand filter
 

amy6152

Member
Apr 4, 2017
17
Rochester, NY
Just eyeballing it with the scale on the side of the tube. You know, the one where you add the water/reagent mix until you can't see the black dot anymore? It's just under 50.
 

Dtkokay

Well-known member
Dec 31, 2019
309
Houston, Texas
Just eyeballing it with the scale on the side of the tube. You know, the one where you add the water/reagent mix until you can't see the black dot anymore? It's just under 50.
Just an FYI that the CYA test results should be rounded up to the next 10. In your example, if you get a result of "49" then round that up to 50. The test isn't that precise because of it's subjective nature, and you're better off erring on the side of reading the CYA on the high side.