I think I have the start of Black Algae - Black spots on bottom of the pool

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I see no reason to SLAM just yet.....do you? I think I would just elevate the chlorine for now and then raise CYA to 60-70 when all is well.

I am not sure that is Black algae. Can you scrape off a sample and see if it is greenish black when smeared on a piece of white paper?
 
It was black and after some brushing turned light brown. Its in my deep end and water is 63 degrees so getting in and scraping is a bit problematic.

Here are some hot off the press numbers. My CYA jumped on me, guess those trichlor pucks do work but they sneak-up on you. I tested three times to make sure. Standing in sun with back facing sun and test belt high in shade from my body. Makes sense though as it's been quite warm here the past week, mid -to high 80's, my pool is in full sun and I've been maintaining 6 to 6.5 FC with three small pieces of puck in the floater left. Until today SWG hasn't been on and right now it's only at 10% having run a total of 4 hours today.

FC - 6.5
CC -0
pH - 7.6
TA - 80
CH - 1050
CYA - 70
Salt - 3,500
CSI - .08

In terms of seeing a reason to slam the only reason is that's what my plaster guy told me to do to get rid of the "organic" material (this is what he called it) at the bottom of my pool. Tried nylon and steel brush and hasn't been working. Went and picked-up bleach and I'm ready to roll if people thing shocking is still a good idea.
 
I still don't see a reason to SLAM. I would elevate and hold the FC to around 10-15 and then go after the stains with the stainless steel brush. If they turn brown again, give them 24 hours and see what they do. Report back.

Do you have those spots around the rest of your pool? Black algae is a "nook and cranny" kind of algae and your spots are out in the open......they just don't look like algae.

Give the steel brush another try.
 
duraleigh said:
Do you have those spots around the rest of your pool? Black algae is a "nook and cranny" kind of algae and your spots are out in the open......they just don't look like algae.

Give the steel brush another try.
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Just brought her down to pH 7 to get my TA down, as soon as I aerate up to 7.2 I'll take FC up to 15 and give the brush a shot.

No other spots in pool, just these.

Thanks!

EDIT: Brushed last night with steel brush, this morning and this afternoon I'll use nylon brush and see how things are looking in the morning.
 
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