Black Algae

AzWildcat

LifeTime Supporter
Jun 22, 2007
26
0
Texas
#1
We have just returned from 8 months over seas and we have black algae, big time. We have about a 25,000 gal Gunite pool. I have been told the "best" way, although not the easiest way to get rid of it was to drain the pool and to either steel brush or use a pressure washer to knock the "heads" off and then to scrub it with liquid chlorine and\or tri-clor tabs until it turns "pinkish-brownish" - then do it again just to be on the safe side. Was told to add a "super-chlorinate" as we fill it up that will take the FC to about 15 PPM and that should do it. On its surface this process makes sense to me but I am not a pool expert. Honestly, at this stage, if this is "surest" way that is fine with me to get rid of it, this process is OK. This pool is in Texas.

What are your thoughts, comments, additional advice etc?
 

JasonLion

LifeTime Supporter
Platinum Supporter
TFP Expert
May 7, 2007
37,879
5
Silver Spring, MD
#2
Welcome to TFP!

Black algae is probably the most difficult kind of algae to get rid of. Some people have had success by gently rubbing the black algae with a trichlor tablet. But if there is a lot of it that might not be practical.
 

Aquaman95

Well-known member
Feb 20, 2008
249
0
#3
Fill the pool in and start over.

Just kidding. The best success I have had is to underwater pressure wash and then get the chlorine up very high for a week or so and daily brush with a combo brush (nylon/stainless bristles).

Just be careful underwater pressure washing with which tip/PSI you use. You want to knock the heads off as efficiently as possible without damaging the plaster. Test it in an inconspicuous area and go from there.
 

waste

LifeTime Supporter
TFP Expert
Mar 29, 2007
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52
Coastalish 'down easter'
#4
Aquaman, that is a very good idea!! Do you think it would be safe to try on a liner pool? (I've 'written my name' on a few plaster pools while pressure washing them in preparation for a replaster - so realize the potential for liner damage :eek: )
 

Aquaman95

Well-known member
Feb 20, 2008
249
0
#5
Which idea, the pressure washing or filling it in and starting over? :lol:

Honestly I don't know about liner pools. I have no experience with them. I'm a little surprised black algae even grows in them. It's such a pain in plaster pools because the roots dig into the plaster. Do the roots go through the liner? If so, wouldn't that just ruin the liner anyway?
 

waste

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TFP Expert
Mar 29, 2007
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0
52
Coastalish 'down easter'
#7
It seems that the roots for black algae grow through :shock: :eek: the waterproof liner!! I've replaced liners with BA and found it to be in the floor in the same areas as the spots on the liner :? We treat the effected areas of the floor with 12.5% liquid chlorine - sometimes it works/ sometimes it doesn't -- It's my belief that the ones that it doesn't work for aren't maintaining their FC - but my customers lie about maintaining their pools:!:

Thanks for the idea of using the pressurewasher to 'knock off' the heads :thumleft:
 

frustratedpoolmom

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In The Industry
May 20, 2007
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44
SWSuburban Chicago, IL
#8
waste said:
It seems that the roots for black algae grow through :shock: :eek: the waterproof liner!! I've replaced liners with BA and found it to be in the floor in the same areas as the spots on the liner :? We treat the effected areas of the floor with 12.5% liquid chlorine - sometimes it works/ sometimes it doesn't -- It's my belief that the ones that it doesn't work for aren't maintaining their FC - but my customers lie about maintaining their pools:!:

Thanks for the idea of using the pressurewasher to 'knock off' the heads :thumleft:
Mmmhmmmm....my algae (?) grew when I was using the Frog and held the recommended 1ppm FC.... :roll: :evil:
 

AzWildcat

LifeTime Supporter
Jun 22, 2007
26
0
Texas
#9
Aquaman - What do you think off the idea of draining the pool and then pressure washing and then brushing the effected areas a couple of times with liquid chlorine and then filling it up with hypo chlorinated water ? I realize it is probably overkill, alot like shooting a snake 5 times when one shot would do it - but then again, sometimes and to some people the value of a nights sleep knowing the snake is dead, dead, dead, dead is worth the cost of the extra bullets. That is the case here if it increasing the probability of a "sure kill."
 

Aquaman95

Well-known member
Feb 20, 2008
249
0
#10
AzWildcat said:
Aquaman - What do you think off the idea of draining the pool and then pressure washing and then brushing the effected areas a couple of times with liquid chlorine and then filling it up with hypo chlorinated water ? I realize it is probably overkill, alot like shooting a snake 5 times when one shot would do it - but then again, sometimes and to some people the value of a nights sleep knowing the snake is dead, dead, dead, dead is worth the cost of the extra bullets. That is the case here if it increasing the probability of a "sure kill."
Well, I'm a big fan of shooting snakes 5 times...I don't trust anything that doesn't have shoulders.

On the pool topic, I don't think draining is going to help you much in this case. You can achieve everything you need to do underwater and you don't run the risk of floating the pool.

What part of TX are you in?
 

AzWildcat

LifeTime Supporter
Jun 22, 2007
26
0
Texas
#11
Katy - which is about 30 miles west of Houston.

OK if don't drain the pool and bust the heads using under water pressure washer, what is your plan of "full engagement" to give me the best shot of not having to hit speed dial for the concrete company. Please, don't be afraid to assume I don't know which end of the bullet goes into the breech of the gun. After all, my high IQ allowed me to agree to replacing perfectly good dirt with a breeding ground for all known water borne menaces with tenacles that attach directly to my wallet.
 

Aquaman95

Well-known member
Feb 20, 2008
249
0
#12
AzWildcat said:
Katy - which is about 30 miles west of Houston.

OK if don't drain the pool and bust the heads using under water pressure washer, what is your plan of "full engagement" to give me the best shot of not having to hit speed dial for the concrete company. Please, don't be afraid to assume I don't know which end of the bullet goes into the breech of the gun. After all, my high IQ allowed me to agree to replacing perfectly good dirt with a breeding ground for all known water borne menaces with tenacles that attach directly to my wallet.
1) Pressure wash.
2) Hit the pool with a ton of bleach while keeping the pH down to 7.2...follow the Chlorine/CYA chart (Yellow Mustard Shock or higher) to determine how high in your case. chlorine-cya-chart-t2346.html
3) Keep the chlorine high and brush it every day with a combo brush. A week should do it.
4) Follow the chlorine/CYA chart to keep your chlorine at correct levels at all times going forward.

"My high IQ allowed me to agree to replacing perfectly good dirt with a breeding ground for all known water borne menaces with tenacles that attach directly to my wallet."

That is the quote of the year!

I'm in Houston as well...in our area I would avoid draining as much as possible, even though it's been reasonably dry.
 

chem geek

LifeTime Supporter
TFP Expert
Mar 28, 2007
12,082
2
San Rafael, CA USA
#13
The key really is to brush or otherwise knock off the head of the algae since it is that protective slime layer that prevents chlorine from killing it. When not protected in that way, the order of heartiness (based on lab studies) of algae is green < black < yellow/mustard so if you get the surface layer off of the black algae then somewhat higher chlorine levels will kill it and keep it away. Using the yellow/mustard chlorine recommendations for shocking will be fine for killing it and if truly gone the normally recommended chlorine levels usually keep it away.

Richard
 

AzWildcat

LifeTime Supporter
Jun 22, 2007
26
0
Texas
#14
It is not very often I get to expose my ignorance publically so here goes:

1) My CYA is about 85 so I thought I'd drain the pool by about 1\3 to lower the CYA, make pressure washing a little easier, and to give me a little "wiggle" room on the Chlorine/CYA chart.
a) How do I get the knocked off heads and "algae body parts" out of the pool ?
Regular filtration (we have a DE filter) and the Polaris ?
b) How much time do I have before the algae starts to grow new protective heads ? It will probably take 2-3 hours (will do a test tonight) to pressure wash the whole thing & I will be in the pool doing it (yep, there is that much BA in the pool). I can wear my super-duper neopreme (sp) camo duck hunting suit as protection if you recommend washing it with a high chlorine content already in it.
c) What kind or strength of bleach do you recommend ? I have never used bleach as a chlorinating agent.

Well, this is kind of a strip tease. I am going to expose my ignorance slowly. The best is yet to come.

Thanks
 

Aquaman95

Well-known member
Feb 20, 2008
249
0
#15
AzWildcat said:
It is not very often I get to expose my ignorance publically so here goes:

1) My CYA is about 85 so I thought I'd drain the pool by about 1\3 to lower the CYA, make pressure washing a little easier, and to give me a little "wiggle" room on the Chlorine/CYA chart.
a) How do I get the knocked off heads and "algae body parts" out of the pool ?
Regular filtration (we have a DE filter) and the Polaris ?
b) How much time do I have before the algae starts to grow new protective heads ? It will probably take 2-3 hours (will do a test tonight) to pressure wash the whole thing & I will be in the pool doing it (yep, there is that much BA in the pool). I can wear my super-duper neopreme (sp) camo duck hunting suit as protection if you recommend washing it with a high chlorine content already in it.
c) What kind or strength of bleach do you recommend ? I have never used bleach as a chlorinating agent.

Well, this is kind of a strip tease. I am going to expose my ignorance slowly. The best is yet to come.

Thanks
1) Yes, get the CYA down and keep it down in the future by discontinuing the use of trichlor tablets.
a) Depending on how much accumulated gunk there is after you're done you may want to vacuum. If it's not enough to really see it then your filter and polaris can handle it.
b) Add the chlorine after you pressure wash. You don't need the duck suit. It won't grow back in 2-3 hours.
c) Plain old unscented laundry bleach from the grocery store will work well. It's readily available as 5.5% and 6% in Houston. Either will work. Just stock up; you're going to need plenty.

You may want to consider using bleach as your regular chlorination in the future. It's cheaper and produces better results if done correctly. Look through the "What's BBB" thread and read some of the pool school subjects.
 

AzWildcat

LifeTime Supporter
Jun 22, 2007
26
0
Texas
#17
OK - Read the BBB article as well as some of the threads re BBB. A whole lot of light bulbs went off. We're talking parallel universes here aren't we ? If one universe is toting around the water test bottle from the pool store you're the least mad at that month and buying what they say you need and bitching about how expensive it is versus the other universe which is taking ownership and responsability every day, getting some education, and testing and tweaking and making adjustments with relativley inexpensive commonly available household products, then I need to be beamed over. Am assumming I will be able to just dial my Rainbow chlorinator to OFF and kiss off using pucks once I go BBB.

Does the Liquadator work well in Texas ?

Will order the test kit today. I do want to go to war against the BA this weekend but will not have the test kit. Suggestions as to how much bleach I might need for a 25K gallon pool and is it OK to "overkill" with bleach for a few days until I can accurately test ? I can monitor my pH and keep it in the 7.2 range with my Walt Disney autograph model test kit and muratic acid.
 

AzWildcat

LifeTime Supporter
Jun 22, 2007
26
0
Texas
#18
Saw that at Warehouse. Dumb question - is liquid chlorine the same as bleach ? Realize it is twice as strong but is it absent the "additives" the trichlor pucks do ?

Thanks
 

frustratedpoolmom

LifeTime Supporter
TFP Expert
In The Industry
May 20, 2007
12,177
0
44
SWSuburban Chicago, IL
#19
AzWildcat said:
Saw that at Warehouse. Dumb question - is liquid chlorine the same as bleach ? Realize it is twice as strong but is it absent the "additives" the trichlor pucks do ?

Thanks
DING DING DING DING DING - we have a winner! :mrgreen:

Twice as strong so use half the amount. The pool calc will allow you to change the %% so it gives you proper dosing.

I love the parellel universe thing! LOL
 

Ohm_Boy

TFP Expert
May 1, 2007
1,344
0
Orlando, FL
#20
Of all the chlorine sanitizing products you can find for your pool, all tend to have other ingredients which will change the overall chemistry of your pool except for liquid chlorine. And, just to help you keep them straight in your mind, let me recap the significant differences among the various LIQUID CHLORINE products...

In the pool store universe, they have
a) Liquid Chlorine. Active ingredient is Sodium Hypochlorite.
b) Liquid "Shock", which is liquid chlorine. Active ingredient is Sodium Hypochlorite.

Now over in the BBB universe, the favorite chlorine product is
a) Liquid laundry bleach. Active ingredient is Sodium Hypochlorite.

So you can easily see the difference among the products. You have to choose from Sodium Hypochlorite, Sodium Hypochlorite, or Sodium Hypochlorite. Naturally, it can be tough to get the right one.

Seriously, the only difference in the liquid products lie in the concentrations. Generally, household bleach is 5.25% to 6% Sodium Hypochlorite, the "official pool" products will typically be 10% to 12% Sodium Hypochlorite.

So yeah, we use ordinary bleach.