Fine black particles settling on bottom of pool.

[Jktbnelson]

I need help trying to figure out what's collecting at the bottom of my above ground pool. There are fine black particle clumps that collect in low places at the bottom of my pool. When disturbed they just disappear, so I believe it's not sand. I do have a sand filter and I also run a dolphin automatic vacuum cleaner quite frequently and nothing seems to rid my pool of this collection. I would appreciate any ideas on what this could be and how to treat it.
Thanks, Kari
27' round ABG pool with CaliMar pump and sand filter that is perfectly balanced.

 

[jeffchap]

That is probably dead algae settling into small divots on the bottom of your pool. You may be on the verge of an algae outbreak. Do you have any test results from one of the approved kits that you can post for us?

 

[kellyfair]

Test results as Jeff said, and I’m curious if you can scoop out a clump and see what it feels like.

 

[Jktbnelson]

I use the TF-100
TC=5
Ph=7.5
CYA=90
TA=250
CH=450
FC=12
CC=1.0

 

[Jktbnelson]

Brrr...I just jumped in my 60 degree water to try and feel it. It does appear more brown once I got eyeball to eyeball with, but it just puffs away as you get close to it.

Test results as Jeff said, and I’m curious if you can scoop out a clump and see what it feels like.

 

[Jktbnelson]

We also had a ton of pollen from our evergreens ~3-4 wks ago, but that stuff is bright yellow. Does it change color as it sits in the pool?

 

[kellyfair]

Brrr...I just jumped in my 60 degree water to try and feel it. It does appear more brown once I got eyeball to eyeball with, but it just puffs away as you get close to it.

LOL! Now that is dedication!

Brown stuff that poofs away is almost certainly algae. Sounds like you need a SLAM!

 

[Jktbnelson]

New to this site. Where do I find the SLAM protocol?

 

[jeffchap]

On the Pool School page.


In a nutshell, raise FC to 40% of CYA (36 ppm in your case). Test and adjust as frequently as you can, but no less than 4 times per day.

Continue until:

1) water is perfectly clear
2) FC drops no more than 1 ppm overnight
3) CC tests .5 or less

With your CYA at 90, it'll take a bit of chlorine to raise your FC to 36. This is why we typically like to SLAM with CYA around 30. It only requires FC to be 12 ppm at that level. If you can drain and refill to lower your CYA somewhat first, it'll save you some money on chlorine. It also takes less R-0871 to test . But that's entirely up to you.