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

QingGuy

Silver Supporter
Mar 22, 2015
481
Las Vegas NV
#1
So the other day I noticed I had some small black spots near the pool drains. I thought they were pill bugs as in the spring/summer we get a lot of them and thought when I turned on my vac this week (try and vac pool once a week) and it would pick them up.

So pool vac ran today and the spots are still there. Grabbed my nylon brush move them around and I could only get say 1 out of a dozen to move. They're black spots on my plaster. My FC is always in recommended range, however, during the winter I haven't brushed the bottom of the pool regularly (did not "close" pool).

Spots are in the deep end, water is 42 so I'm not jumping in to scrub, so it looks like I'll get a stainless brush and try and brush the spots 7' underwater. Any suggestions other than what I found here - Pool School - Black Algae

Wish me luck!
 

kimkats

Mod Squad
LifeTime Supporter
Jul 10, 2012
36,013
Tallahassee, FL
#2
OH no! I KNOW you have kept your levels balanced! I wonder if you can rig up a way to put a puck on top of one of the spots? maybe in a holey bag like mesh? That way you can get it in and out without getting in the burrrrr your self!

Kim:kim:
 

QingGuy

Silver Supporter
Mar 22, 2015
481
Las Vegas NV
#3
Yea it's a drag. Got a couple more spots up so I'm going to keep brushing twice a day for a week and see if the come loose.


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Dz7

In The Industry
Jun 20, 2016
32
Florida
#8
Right. People typically use the granulated version when the problem is more widespread and they don't feel like holding a puck on every spot. Lazy way out.
 

FloridaSolarPro

LifeTime Supporter
In The Industry
Oct 2, 2011
49
Fort Myers, FL
#9
Right. People typically use the granulated version when the problem is more widespread and they don't feel like holding a puck on every spot. Lazy way out.
You mean the lazy way that worked like a charm? Yes, trichlor. The spots were at the end of a swim lane that gets poor circulation because of the pool design. I turned the pump off and used a healthy dose sprinkled right over the area with the spots. 8 hours later I started the pump back up and vacuumed the area. Problem 100% solved the easy way, aka the lazy way I guess.

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consoleman

Well-known member
Feb 18, 2014
164
Houston, TX
#13
Caco.
Is it necessary to have the fc levels at shock level when using the rubbing the tricholr on the black algae or can i have them at 7-9?

Id like to be in the pool when treating the black algae but rather not a shock fc levles


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Caco

Well-known member
#14
Consoleman
I would let the FC drop to 1-2 points below your slam level and then get in the pool
It is safe to swim at that level
7-9FC is your daily maintenance level

So we dont keep hijacking the OP's thread, why dont you start your own thread, and post a full set of test results, so we can give you advice specific to your situation
 

QingGuy

Silver Supporter
Mar 22, 2015
481
Las Vegas NV
#15
UPDATE: I have pneumonia so I haven't been diligent about brushing our getting my son to brush. Wire brush was delivered and son brushed this morning, looked this afternoon and spots are all there but they're lighter, progress? FC is 7, CC is .05
 

QingGuy

Silver Supporter
Mar 22, 2015
481
Las Vegas NV
#17
Plaster guy just left and said it's "organic" Suggested bumping-up FC level and brush, said it would come off. Any suggestions on how high to take my FC?

Here are my current numbers:
FC - 6
CC - .5
pH - 7.5
TA - 80 (going to bring this down to 60 AGAIN before I do this)
CH - 1050
CYA - 30
Salt - 3,500
CSI - .05
 

duraleigh

Admin
Mod Squad
TFP Expert
Platinum Supporter
LifeTime Supporter
In The Industry
Apr 1, 2007
31,333
Sebring, Florida
#18
Qingguy,

First, I am gonna suggest you bump your CYA to 60-70. 30 is too low for the coming Vegas summer and an SWG.

After that bump, I would bring the FC up to around 15 or so. There is no Magic number but that's a good place to be very effective. That steel brush has to be used, too. Don't erode a hole in your finish but use it often to expose that black algae to the chlorine.
 

QingGuy

Silver Supporter
Mar 22, 2015
481
Las Vegas NV
#19
Qingguy,

First, I am gonna suggest you bump your CYA to 60-70. 30 is too low for the coming Vegas summer and an SWG.

After that bump, I would bring the FC up to around 15 or so. There is no Magic number but that's a good place to be very effective. That steel brush has to be used, too. Don't erode a hole in your finish but use it often to expose that black algae to the chlorine.
Yep, coming out of my winter levels. During the winter I float pucks to maintain 5 FC, doesn't take much and doesn't seem to raise the CYA level at all either. I'll be raising the CYA shortly, not sure if I'll get to it before I shock but soon. Thanks for the tip on the wire brush use.
 

QingGuy

Silver Supporter
Mar 22, 2015
481
Las Vegas NV
#20
Duraleigh you got me thinking, do you think I should raise my CYA and then slam? This is my first slam btw.

Do you think I should not worry about lowering my TA until after my slam? I guess I'm needing guidance on order of importance.

Heres a picture of the spots


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