Black Algae

pooladdict

In The Industry
TFP Guide
May 15, 2007
819
0
New Brunswick Canada
#5
Are you sure they are in fact black algae? Do they have what appears to be legs growing off them?

Try placing a VIt C tab on them, if that doesn't work, try some dichlor for a short time. Do not leave the Dichlor on it for long though.
 

chem geek

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TFP Expert
Mar 28, 2007
12,082
2
San Rafael, CA USA
#10
Hard to say if that's algae or a stain. If you scrape some of it off and smear it on a white piece of paper, then if it's green or dark green, then it's black algae for sure. That would normally only grow in a pool with proper FC/CYA levels if the circulation in that area were very poor. You'd also want to completely get rid of it at its roots by scraping it off and exposing it to high chlorine level. A Trichlor puck would do that, but would also likely leave a mark on your pool surface and you've got such a nice looking surface I wouldn't want to ruin it.
 

boston62

LifeTime Supporter
Jun 7, 2014
472
0
Fort Myers, Florida
#12
I put a vit c tablet on it nothing happend, then the puck left for 2 hours nothing...wish I knew what it was.

The only thing I can think of from using MA or some other chemicals brought it out from the plaster finish.
 

jblizzle

Mod Squad
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May 19, 2010
41,197
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Tucson, AZ
#13
You sure it is not just a black stone in the plaster, like all the blue ones?

Oh, did you say that they just showed up and were not there before?
 

boston62

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Jun 7, 2014
472
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Fort Myers, Florida
#14
You sure it is not just a black stone in the plaster, like all the blue ones?

Oh, did you say that they just showed up and were not there before?
They were not there before they just started showing up, when I had a pool man taking care of it before TFP they were not there but the FC was at 16 and CYA was over 100. When I started to take over I added the swg..then since March 2014 they started showing up..They look like stone, but what made them show up...Thank you
 

boston62

LifeTime Supporter
Jun 7, 2014
472
0
Fort Myers, Florida
#15
What could I have done wrong..

Merged by moderator. Please keep all related questions discussion in the same thread. jblizzle

When I took over the pool from the pool man, I had no algae, at that time FC was 16 according to pool store. This all before getting my test kit and TFP.

Now the pool FC has never been below 5, and balanced... Now I have started getting black spots started with 1 or 2 now about 10, just trying to see if I did not take care of pool right. I have been steel brushing algae spots...The pool does look great except these growing spots.

Thank you
 

JasonLion

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TFP Expert
May 7, 2007
37,879
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Silver Spring, MD
#16
Re: What could I have done wrong..

As you should know by now, questions like this one need to be accompanied by a full set of water test results. Without that additional information it is impossible for us to help you.

Also, do these black spots brush off?
 

boston62

LifeTime Supporter
Jun 7, 2014
472
0
Fort Myers, Florida
#17
Re: What could I have done wrong..

Jason sorry about that..

FC 8
CC 0
PH 7.6
TA 75
CYA 70
Salt 3300

They do not brush off with steel brush, 3 " tablet, or vitamin c... They seem to just appear..

I did add a swg & Jandy VS Pump.
 

duraleigh

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Apr 1, 2007
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Sebring, Florida
tftestkits.net
#18
Re: What could I have done wrong..

Can you scrape them with your fingernail and get a dark greenish cast when rubbed on a white sheet of paper?

That would indicate black algae, but based on your description, I would doubt that's what it is and I doubt it will scrape off.

I would suspect it is some kind of mineral deposit.

Got a pic?