Black Algae

Geaux

Member
Feb 6, 2020
12
Albany, Louisiana
Not really new to TFP but first time poster. We built a new home 7 years ago with a pool and have always had a company manage our pool. Now, after being messed around by pool company and my job easing up I am ready to manage our pool myself. We have fought Black algae repeatedly over the years and after seriously monitoring my pool company of the past few months I have realized why. They have ruined my SWG and stained the bottom of my pool which I will ask about after as soon as I get the Black Algea eradicated. The algae is not that bad, only a few spots but I, of course don't want it to vet that bad. Anyway, enough of all that, here are my pool test results.
FC. 1
PH 7.5
TA. 80
CH 625
CYA. 10
Salt. 3900

I know my CYA is very low and my FC is a bit low but I feel I need to SLAM it to make sure I get rid of the algae but not sure. Looking for recommendations.
Thanks.
 

JamesW

TFP Expert
Mar 2, 2011
21,553
Some of that looks like it could be black algae. Black algae is like black mold. You should be able to scrape some off and it should be mushy like mold. If you smear it on a paper towel, it should be black, bluish or green.

Other spots look more like metal stains. Metal stains will usually react to vitamin C (ascorbic acid). Try putting a vitamin C tablet on a spot to see if the spot disappears or reacts in any way.
 
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setsailsoon

Gold Supporter
LifeTime Supporter
TFP Guide
Oct 25, 2015
3,655
Stuart/FL
Pool Size
12800
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
CircuPool RJ-30 Plus
g,

Looking back at your logs all the pH readings are below minimum. This makes you ripe for an algae attack... probably lower temps right now kept it from getting worse. I agree with James that it looks like you may have both. While your figuring out if it's a metal issue or algae or both and what to do about it I'd add some liquid chlorine to FC 5 ppm.

Chris
 

JamesW

TFP Expert
Mar 2, 2011
21,553
Your CYA might be zero.

Did the service company ever report the chemistry readings to you?

Did the service company ever tell you what chemicals were being added?

If you doubt the test readings, you need to verify a different way.

If you're sure about the readings, you need to add some CYA.
 

Geaux

Member
Feb 6, 2020
12
Albany, Louisiana
Your CYA might be zero.

Did the service company ever report the chemistry readings to you?

Did the service company ever tell you what chemicals were being added?

If you doubt the test readings, you need to verify a different way.

If you're sure about the readings, you need to add some CYA.
They reported the PH, Chlorine and Alkalinity to me once a week and the chemicals added. I just started paying more attention all of a sudden when my SWG went out and the Black algae became a persistent problem.
 

JamesW

TFP Expert
Mar 2, 2011
21,553
If the company wasn't reporting the CYA, they probably weren't testing it.

Do you have a K-1766 salt test kit or are you getting the reading from the EasyTouch?

What chemicals were added this year?
 

Geaux

Member
Feb 6, 2020
12
Albany, Louisiana
I've just been using the reading from my easy touch. Theu have been adding way too many chemicals specifically way too much granular chlorine which kept clogging up my filter. Algaecides, soda ash, dry acid. Sodium bicarbonate and stabilizer.
 

JamesW

TFP Expert
Mar 2, 2011
21,553
Seems like they didn't know what they were doing.

How much stabilizer was added this year and when was it added?