Algae or something else?

[DareDog]

seemed like all summer I have this on bottom of the pool. It brushes away and then comes back. I have done a SLAM a few times and it still comes back. FC is 12 and CC is 0.5.


not sure if its algae or something coming off from the pine needles?

 

[Texas Splash]

Looks kind of heavy and dark to be algae so quickly. Water seems pristine. Anything unusual around the pool, on patio or car surfaces? I would ask if it feels slimy like algae, but if it's something falling it, it probably feels that way anyways. Do you use a skimmer sock in the poolside skimmer? If you're passing the Overnight Chlorine Loss Test, I would suspect something falling or blowing in.

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For an FC of 12, is your CYA about 30? Wait, I just noticed you're a salt pool. Should be a CYA of 70. So at what FC level did you SLAM previously? Is it at 12 now because you finished the SLAM and it's falling down?

When was the past time you did a filter deep clean on the sand?

 

[DareDog]

Looks kind of heavy and dark to be algae so quickly. Water seems pristine. Anything unusual around the pool, on patio or car surfaces? I would ask if it feels slimy like algae, but if it's something falling it, it probably feels that way anyways. Do you use a skimmer sock in the poolside skimmer? If you're passing the Overnight Chlorine Loss Test, I would suspect something falling or blowing in.

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For an FC of 12, is your CYA about 30? Wait, I just noticed you're a salt pool. Should be a CYA of 70. So at what FC level did you SLAM previously? Is it at 12 now because you finished the SLAM and it's falling down?

When was the past time you did a filter deep clean on the sand?

Must be something blowing off the trees and in to the pool. Nothing on the pool deck or chairs. Row of tall pines 12’’ away from the pool and then 2 big trees 5’’ away. CYA is 70. Slammed at 28 ppm. It’s falling down after the slam. I do not use a skimmer sock, should I? Never have done a filter deep clean. Pool is 11 months old. Should I do a deep clean?

 

[Texas Splash]

I do not use a skimmer sock, should I? Pool is 11 months old. Should I do a deep clean?

Yes and Possibly. The skimmer sock (either a hairnet or 1 gallon paint strainer) does wonders to collect surface debris before it gets to the filter. I never run my pump without it. As for the deep clean, some owners go a few years before doing it, usually because a SLAM wouldn't clear. Others do it religiously each year. Being so new I wouldn't think you need to, except you have had to SLAM a few times. Perhaps at some point it may be worth investigating. When you get ready, here's the page: Deep Cleaning a Sand Filter.