Algae or Dirt? (newbie)

[friguy3]

Might be a dumb question, but im new lol and couldnt find any good pictures like mine. Basically, do you think this is algae or dirt? It rubbed a lot off with just a paper towel, some of it looks like ill have to scrub a little harder, but should come off. It didnt look "green" to me when I wiped it on the paper towel. Ive done a couple over night chlorine tests (3->2.2, 14.4->16.8, 11.6->12, yes, my last 2 test the FC went up! CC is usually 0 to 0.5), havent had a >1.0 drop or > 0.5 CC. I feel my steps are slippery (liner) (have a different thread for that!) and just want to be sure Im not missing something. Thank you!!

Most recent tests (its hard to be accurate with these colors!)
pH 7.6 (added some pH down to get it closer to 7.3)
CYA65
FC 3 (I was letting the FC drift down, SWCG was at 0% for a few days, now back to 60% and FC is up near 10 now)
CC 0.2
Alk 110-120

 

[tim5055]

Just off the top of my head I'm going to say dirt, but a couple of things concern me. With CYA 65 (I say 70) your FC should never drop below 5, with a target of 8. So your first test you were low on FC and second you are high. I've been in several vinyl lined pools with "slippery" steps but no algae.

It's a basic question, but when you conducted the Overnight FC Loss Test (OCLT) did you run the pump and turn off the SWCG?

 

[friguy3]

Just off the top of my head I'm going to say dirt, but a couple of things concern me. With CYA 65 (I say 70) your FC should never drop below 5, with a target of 8. So your first test you were low on FC and second you are high. I've been in several vinyl lined pools with "slippery" steps but no algae.

It's a basic question, but when you conducted the Overnight FC Loss Test (OCLT) did you run the pump and turn off the SWCG?

Yes. SWCG was at 0%. I ran the pump for 30min or so after sunset, then tested and it ran all night. Then tested early in the AM. My first was low, 3. Then I added some shock, dont ask why. My FC went way up, ~20, did 2 OCLT's and the FC drifted down to 3...and thats when I turned my SWCG up to 60%. Ran for maybe 2 days and this am with a dipstick (dont judge) it was near 10. Im still learning what % I should be at lol.

-As for the slippery steps, we have bath mats on the first step, work great and no more slip and falls!). They actually dont look bad.

-THANKS!