Greenish Dirt or Algae on bottom of pool

MarianParoo

Well-known member
Aug 16, 2014
4,615
Northern IL
Eagerly awaiting results! Be sure that if you make any chlorine addition tonight, that you wait 1/2 to 1 hour later and test again to know EXACTLY what your FC/CC reads so that you get an accurate evening reading. Poolmath "goals" can in actuality be under or over shot. Make sense?
 

Blake1989

Well-known member
May 18, 2012
163
Birmingham, Alabama
Absolutely! To answer your question earlier Marian, it usually accumulates near the pool wall in clumps. I got in today and swam underwater. I felt it in between my fingers. Felt like a fine sand but not rough at all. Not slimy but not dry either. There wasn't a lot in today. Probably about two salt shakers worth and in different spots.
 

MarianParoo

Well-known member
Aug 16, 2014
4,615
Northern IL
Hmmmm. If it changes locations, I am inclined to think it's just gunk. I could very well be wrong, but most persistent algae types tend to appear in the same places over time. Let's see what your OCLT tells us.
 

JamesW

TFP Expert
Mar 2, 2011
21,505
Don't think that it's pollen. There's not a lot of algae compared to other types of algae and this type is very unreactive to chlorine. Therefore, it's not unusual to pass the OCLT with this type of algae.
 

Blake1989

Well-known member
May 18, 2012
163
Birmingham, Alabama
Update: keeping at the shock level for mustard algae. Filter flow slowed considerably. Back washed and added more DE substitute. Water is crystal clear and no sign of any algae on the bottom.
 

JamesW

TFP Expert
Mar 2, 2011
21,505
Sounds like you might be done with the Slam. I would suggest keeping the pump on continuously for one week and maintain 15% for one week. Brush daily and vacuum as needed.