Algae bloom during SLAM

[JABRY5]

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.

 

[Richard320]

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?

 

[JABRY5]

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.

 

[IceShadow]

Make sure you run on Rinse for a minute or so after backwashing before going back to filter.

 

[JABRY5]

First SLAM is complete! Thanks to all on this site who have indirectly added years to my life and green to my wallet.