Algae bloom during SLAM


Active member
Apr 25, 2020
Coppell, TX
I've been SLAMing for the last week with a sand filter. Pool was looking better every day. Have been checking CYA/FC 2-4 times a day. Brushing the walls. Vacuuming every night. Was seeing results. Passed every test but the clear water test, and I was just about finished.

My CYA was 30 this morning and 30 in the afternoon. My FC was 16 this morning and 15 this afternoon.

Yet for the first time during the SLAM, my water took a step backward and turned cloudier today, indicating an algae bloom. How is that even possible? I am testing from the same place in the pool every time. I have the Taylor K-2006C and none of the reagents I am using are expired.


TFP Expert
LifeTime Supporter
Jan 6, 2010
San Dimas, CA (LA County)
There could be other reasons than algae to cause cloudiness with the FC so high. Did it turn cloudy after you added more bleach? After brushing? Did you backwash and maybe not rinse well after?


Active member
Apr 25, 2020
Coppell, TX
There might be something to the backwash/rinse-induced cloudiness. I backwashed yesterday morning after several days of not having to. Water was running clear (I thought) after 45 seconds of rinsing, but maybe not quite clear enough. Pool is back on track this morning.


Gold Supporter
TFP Guide
Jun 8, 2019
Milwaukee, WI
Pool Size
Liquid Chlorine
Make sure you run on Rinse for a minute or so after backwashing before going back to filter. :)
Thread Status
Hello , There was no answer in this thread for more than 60 days.
It can take a long time to get an up-to-date response or contact with relevant users.