New member
Jun 10, 2021
medford new york
So I added flocculant to my pool not realizing I cant use it with a cartridge filter :O( I replaced my cartridge filter with a new one after i got most of the flocculant out. pool is pretty clear. but 24 hours after i vacuum i keep getting this stuff at the bottom of the pool. it keeps coming back im assuming its the flocculant. how do I get it to stay out.IMG_6520.jpgIMG_6514.jpg


Gold Supporter
Jun 18, 2014
Glassboro, NJ
That looks like dead algae. New Pool? How do you chlorinate? Pucks? Liquid?

Please fill out your signature so we can see what you pool is and your equipment. Like mine.

You need to get one of the recommended test kits Test Kits Compared.

Post back with numbers from your test kit.


Bronze Supporter
May 29, 2019
Two things. Follow the advice above on getting a test kit.

Second, pucks will continue to raise your stabilizer (also called CYA). Using them to chlorinate will be ticking time bomb. As the stabilizer goes up the effectiveness of the chlorine is reduced and eventually you will have algea outbreaks. You are already at 85. If you read the Pool School Water Chemistry you'll see that the target range is 30-60. I would stop using pucks and go to adding Liquid Chlorine daily for your sanitation needs.

Now, unfortunately you cannot put much stock into pool store testing. It is very inaccurate unfortunately. That is why you need your own proper test kit that is capable of doing FAS-DPD for testing. See the link JoeSelf posted for getting a real test kit.

Also, assuming your CYA is really 85 see this chart for your current chlorine needs: