what does black algae look like?

teppy

Well-known member
Nov 11, 2007
120
Louisiana
#1
I was trying to find photos of different algaes so that i can know what they look like. I was brushing my pool this morning when I noticed what looked like a leaf but it wasn't. Its not really black or raised. I can't feel it all when I rub my fingers over it. It kind of looks like a tea colored stain. I'm attatching a photo.
 

frustratedpoolmom

TFP Expert
LifeTime Supporter
In The Industry
May 20, 2007
12,177
SWSuburban Chicago, IL
#5
That's sweet....

How big is the stain? I had some metal sitting on the bottom of my pool, it was a hair clip or something...anyway, 2 summers ago when my ph drifted to low, it rusted while it sat there, unnoticed for a few days....left a stain.

Try the old tablet trick. Absorbic Acid tablet, if it comes off it's metal; chlorine tablet, let it sit on the stain and if it fades its organic.

I have a stain in my pool from an old outbreak of black algae, here's a photo. (Scroll down)
post5558.html?hilit=#p5558
 

waste

TFP Expert
LifeTime Supporter
Mar 29, 2007
4,160
Coastalish 'down easter'
#6
As black algae was in the title of this post, the way I've been told you can readily identify if it's black algae is to scrape some of the stuff off with a fingernail and rub that on a white business card - if the 'smear' looks green on the card, it's black algae.
 

chem geek

TFP Expert
LifeTime Supporter
Mar 28, 2007
12,082
San Rafael, CA USA
#7
This link (which for technical reasons I do not understand may say Forbidden at which point you need to click on the URL entry field in the browser and press Enter) shows a picture of some advanced nasty black algae. You can see how its concentrated and not diffuse. It starts off as black spots, but they are rather sharply defined. Diffuse spots are more commonly metal stains, especially if circular. If oblong, diffuse markings are often organic stains such as from pine/cedar needles or leaves.
 

teppy

Well-known member
Nov 11, 2007
120
Louisiana
#8
chemgeek,
that is really nasty looking. Yuk. I don't think thats what I have. As a matter of fact, I went out yesterday and mine has just about magically disappeared. The only thing I did was brush it with my steel pool brush after I first saw it. I think it may have been a leaf stain. I shocked my pool for the first time last weekend to try to get rid of some bugs. My chlorine was up to 20ppm. Its just now down to 5 this morning. Maybe the high chlorine level was making that leaf break down fast and left a stain on only 12 hours from what I can figure because I am out there every morning skimming and checking things. I think maybe that after removing the leaf that the chlorine being still high at about 8 may have cleared the stain. I don't know. I'm just guessing here. Its all new to me and I am learning so much here. I'm just glad to know that I don't have black algae. That is just so gross.