Black algae? Help

Jump to latest Follow Reply
S

SC Shells

Member
Dec 2, 2022
6
South Carolina
Hi All. I noticed yesterday for the first time some blackish spots / smudges on the bottom of the pool. I've been testing chemistry every day, and other than battling high ph (new gunite pool), chemistry has been good and water has been crystal clear all summer. I went to Leslies and they tested the water + recommended I add 25 fl oz of Leslie's Black Algae Killer, which I di about 24 hours ago. The original spots are fading but now there are more spots. They do not come off when brushing with a wire brush. I hand scraped with a paint scraper, and the stain does come off and looks brownish / black on the paper towel when transferred. Looking for some help on next steps. Details of pool: Gunite, 16X34, 3' to 7', salt water (Pentair), new build - finished in April 2023. Chemistry yesterday:
Free chlorine - 2.85
pH - 8.0
Total Alkalinity - 111ppm
Cyanuric Acid - 58
Iron - 0
Copper - 0.1
Phosphates - 610 ppb
Salt - 2883 ppm

I need to add salt and adjust ph and assuming I should shock it, but not sure which order since I added algae killer yesterday. Any help is appreciated.

Photos are difficult to capture b/c he pool surface is dark (steel blue - Diamondbrite) but I've attached some.
 

Attachments

  • pool 1.jpeg
    pool 1.jpeg
    209.8 KB · Views: 22
  • pool 2.jpeg
    pool 2.jpeg
    475.7 KB · Views: 20
Free chlorine - 2.85
pH - 8.0
Total Alkalinity - 111ppm
Cyanuric Acid - 58
Iron - 0
Copper - 0.1
Phosphates - 610 ppb
Salt - 2883 ppm

What copper has already been added?

Can you show the whole pool and the system?

The newest addition of copper will put your copper level at 0.45 ppm now, which is going to cause copper stains.
 
  • Like
Reactions: Bperry and Mdragger88
I've taken some additional photos. These spots were not there yesterday when I added the algae killer. I have a stain test kit on order but it's not here til Wednesday. Since the path for treating algae seems almost the opposite than copper stains, what is recommended in the meantime? I've not added any copper before yesterday.
 

Attachments

  • pool3.jpeg
    pool3.jpeg
    329.4 KB · Views: 7
  • pool4.jpeg
    pool4.jpeg
    250.9 KB · Views: 7
  • pool5.jpeg
    pool5.jpeg
    272 KB · Views: 7
Can you scrape any off?

Black algae is a type of bacteria like black mold that will be dark green to blue or black when wiped on a paper towel.

Put a vitamin C tablet on a spot to see what happens.
 
I'm attaching pics of the whole pool and the systems.

When I rub a vitamin C tablet on it, where I rub comes off. I have also left a few to dissolve (it's pretty deep so it's hard for me to do).
 

Attachments

  • poolfull.jpeg
    poolfull.jpeg
    783.1 KB · Views: 9
  • poolsys1.jpeg
    poolsys1.jpeg
    578.5 KB · Views: 10
  • poolsys2.jpeg
    poolsys2.jpeg
    555.2 KB · Views: 10
Can you open the filter and show the cartridges?

If the copper is high, then you will probably see a blue or turquoise color in the filters.

If there is no obvious turquoise or blue, then the copper is low, but it can still stain.

The water seems cloudy and dirty; are you keeping up with the maintenance?
 
  • Like
Reactions: Mdragger88

Enjoying this content?

Support TFP with a donation.

Give Support
SC Shells said:
I've taken some additional photos. These spots were not there yesterday when I added the algae killer. I have a stain test kit on order but it's not here til Wednesday. Since the path for treating algae seems almost the opposite than copper stains, what is recommended in the meantime? I've not added any copper before yesterday.
Click to expand...
You would treat the algae first then deal with any stains.
If those results are even close to accurate your fc is low FC/CYA Levels
 
SC Shells said:
Hi All. I noticed yesterday for the first time some blackish spots / smudges on the bottom of the pool. I've been testing chemistry every day, and other than battling high ph (new gunite pool), chemistry has been good and water has been crystal clear all summer. I went to Leslies and they tested the water + recommended I add 25 fl oz of Leslie's Black Algae Killer, which I di about 24 hours ago. The original spots are fading but now there are more spots. They do not come off when brushing with a wire brush. I hand scraped with a paint scraper, and the stain does come off and looks brownish / black on the paper towel when transferred. Looking for some help on next steps. Details of pool: Gunite, 16X34, 3' to 7', salt water (Pentair), new build - finished in April 2023. Chemistry yesterday:
Free chlorine - 2.85
pH - 8.0
Total Alkalinity - 111ppm
Cyanuric Acid - 58
Iron - 0
Copper - 0.1
Phosphates - 610 ppb
Salt - 2883 ppm

I need to add salt and adjust ph and assuming I should shock it, but not sure which order since I added algae killer yesterday. Any help is appreciated.

Photos are difficult to capture b/c he pool surface is dark (steel blue - Diamondbrite) but I've attached some.
Click to expand...
Don’t trust Leslie’s water test.
 
Thanks all. Some responses to the above questions / comments:
The pool water is clear. It's not dirty or cloudy. The pictures must just not be accurate.
Yes we are keeping up with the maintenance. We just cleaned the filter this morning and it was not green or black. It was a little dirty, but we have been cleaning it weekly because we have had a lot of rain. We also brush weekly and vacuum every day.
I test every day at home using a Taylor kit and my readings were similar to Leslies. I just posted theirs b/c they gave me a printout. My home kit was showing slightly higher ph (8.2) but that was the only real difference.
 
  • Like
Reactions: JamesW
That’s great you have & use a kit. Which one is it?
Also, Please post your own results-
Same sentiment still applies,
your fc is low for your cya - you want to be in target 🎯 range for regular maintenance purposes. Falling Below minimum invites algae & nasties to grow.
IMG_7052.jpeg
Your cya is also low for a swcg pool but before increasing it to the recommended 70/80 you should to take care of any algae - even if the pool looks clear you should probably do an
Overnight Chlorine Loss Test to rule out a problem that requires the SLAM Process since fc has been below minimum.
As for any confirmed black algae you would follow the guide Herman posted above which is taken care of a little differently. Please don’t add anymore copper stuff. You really don’t want copper in your water.
Please fill out your signature with all your equipment, test kit & pool details. It really helps you get the most accurate advice.

Create Your Signature - Further Reading

www.google.com www.google.com
 
You must log in or register to reply here.
Thread Status
Hello , This thread has been inactive for over 60 days. New postings here are unlikely to be seen or responded to by other members. For better visibility, consider Starting A New Thread.
Top Bottom
Back
Jump to latest Follow Reply