One pool guy told me that Black algae is almost impossible to kill. Is it true?

NewB77777

Active member
Dec 1, 2019
36
Los Angeles
Hi,
Our family purchased home with pool about 20,000 gallon.
So everything regarding pool is new to me.

I saw there were black thing bottom of pool.
So I called one pool guy, and he told me that it looks like black algae(he told me he is not sure. so He told to drain first).
And he told me that if it is black algae, then it is impossible to kill it because they root under plaster.

I already drained water.
Please let me know what is the best way to kill black algae.
I searched around online and I saw that Acid, Chlorine, or Algae removal dedicated chemical is available.
And my uncle told me to grind it with grinder. And my father told me to torch it with fire :)
Because we emptied pool, I think it is good time to clean our pool, not only for killing black algae
Please let me know what I need to do, and also let me know best place that I can buy from.
I'm in Los Angles area.

BTW, is it better to hire pool guy for killing and clean pool and/or regular pool managing, or is it simple enough(and not time consuming) to do myself?
In case I hire pool guy, what I can expect from him to do for regular pool managing?

Please let me know.
Thanks.
 

YippeeSkippy

Mod Squad
LifeTime Supporter
Jan 17, 2012
11,668
Evans, Georgia
Welcome to TFP, NewB77777... glad to have you here!

As to your question, yes you can kill black algae *if that is what it truly is* but I won't say its not going to take some effort.
First off- we have a wealth of teaching/learning articles in Pool School and here is one on Black Algae:


Without having water in the pool we can't determine if your chlorine levels were adequate. In preparation for when you refill the pool, I'd highly suggest obtaining one of the two test kits we recommend- either the TF-100 or K-2006C.
The TF-100 XL would be particularly helpful to you as it has more reagents for the high chlorine tests you'll be needing to run.
www.tftestkits.net
Otherwise you can find the Taylor K-2006C (no other is recommended) on Amazon. Pool stores rarely have the C version, and don't let anyone pawn a K-2005 version on you as it is missing that FAS-DPD tester.

If you scrape up some of the stain on to an index card, can you smear it?? Can you take a picture of the pool and stains in it for us?

Do you know how the previous owner cared for the pool? Which chemicals were used? Do you have a heater?

My first advice is to get some cheap Vitamin C chewable tablets and put them in a thin sock or stocking leg and crush'em up a bit. Wet an area of stain and wet the sock and hold it there for a few minutes. Does it alter the stain?

Next try to hold a wet chlorine puck (no "plus" types of pucks, just plain chlorine puck) to the wet stain (wear gloves) and after a few minutes did that alter it?

I am concerned that being empty, the above tests may alter your finish slightly..... perform at your own risk. This is what we tell folks with filled pools to do.

Not all algae is "black" algae.... sometimes its just regular ole algae, or possibly metal stains.

Maddie :flower:
 
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NewB77777

Active member
Dec 1, 2019
36
Los Angeles
Thank you Maddie!
After we purchased the house, we didn't do nothing for pool for about a month.
And I think the previous owner also stopped chemical few weeks before selling the house.
And I emptied already.
So I think there is no point to check chemical for now.

I already saw the article, and saw couple of youtube videos about black algae.
What I learned is.. if I keep all chemicals in good range, and if I keep removing food(I forgot the name) for black algae,
black algae will not come back again. Is it right?

Can you please let me know what is the best way to kill black algae.
I searched around online and I saw that Acid, Chlorine, or Algae removal dedicated chemical is available.

What I'm going to do is I'm going to pressure water to clean whole pool.
(Not sure If I still need to use bleach or chlorine or acid to clean whole pool even though I use pressure water.)
And I'm going to scrap or grind with grinder(not sure If it is good idea. Plz let me know) black algae or torch(not sure If it is good idea. Plz let me know) black algae, and will use one among acid, chlorine, or algaecide to kill black algae.
And will fill the pool again, and will put all chemicals necessary.

I live in Los Angeles area.
Can you let me know the best place to buy acid, chlorine, and algaecide that I can apply to emptied pool?
BTW, can I use bleach(like Clorox that I can buy from HD) instead of chlorine?

And is it better to hire pool guy for regular pool managing, or is it simple enough(and not time consuming) to do myself?
If I do myself, how much do I expect to spend to buy all necessary chemical monthly?

Little bit about my pool
It is little more than 20,000 gallon.
it has cartridge filter, and it has heater too, and it has automatic vacuum(pool guy told me it is one of the best one in the market which is already discontinued)
Tomorrow morning, I will check exact model number, and will update informations.

Thank you!
 

NewB77777

Active member
Dec 1, 2019
36
Los Angeles
And one more question..
Regarding black algae, if it is hard to kill completely it because they root deeply, how about just remove plaster where the black algae exist, and patch with new plaster?
I think it might be easier. What do you think?
 

wireform

Silver Supporter
In The Industry
Aug 15, 2017
496
Spring Valley, NY
I think you need to heed advice here entirely. Unfortunately you listened to to other advice prior to coming here. We would not have told you to empty pool from the get go. Now that the pool is empty the unknown is unknown and so much for that. Just follow the new instructions they're giving you and and go from there. No, no pressure washing now, No plaster grinding either. The faster we get the answers we are looking for the faster you will get help. Keeping your pool empty may not be a good thing at all and risks your pool from collapsing. So now the ball is in your hands.....
 
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Etchase

Active member
May 22, 2019
31
Hawaii
After you have scraped off as much of the algae you can, a pressure washer is good for this, I have found putting a towel over the algae and saturating it with chlorine for a couple hours, seems to help. You probably could have accomplished the same with water in the pool. Acid wash and pressure washing roughs up the plaster a bit which isn’t as good as having perfectly smooth pristine plaster, but if your beyond that point many people use acid or a pressure washer to brighten up the plaster.
 
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kimkats

Mod Squad
LifeTime Supporter
Jul 10, 2012
41,557
Tallahassee, FL
Do NOT torch the plaster! Do not grind the plaster. Do not remove any plaster. Any of this may ruin the plaster that is there. It will do more harm than good.

Here are your moves going forward:

-re-fill the pool
-order test kit (look in my siggy below for where to get the TF-100. I would get the XL version
-Look in my siggy for the recommended chemicals link. That will tell you what we use in our pools. Do NOT go buy everything on the list as you will not need all of it yet or ever.

Chlorine has to be PLAIN. Clorox has started adding "chlor max" or something like that to their chlorine :( this has caused some foaming in the past. Find PLAIN chlorine or bleach. Your pool store might sell it in re-fillable jugs. Do NOT buy anything else from them.

That should get you started on the right path.

Kim:kim:
 
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NewB77777

Active member
Dec 1, 2019
36
Los Angeles
So, don't I even need to clean my pool Or do I have to clean it before fill water?

If pressure wash might damage plaster, then I think I can adjust the power.
Or I can buy just nozzle for my garden hose.

I already emptied our pool.
So I want to fill water ASAP.
And I want to make it sure the best way to clean.
I saw a youtube video(
), and he used pressure wash, and chlorine.
Not sure I can follow the same way.

I took some pictures of my pool and equipment.
Please let me know.

IMG_5071.JPG

Do NOT torch the plaster! Do not grind the plaster. Do not remove any plaster. Any of this may ruin the plaster that is there. It will do more harm than good.

Here are your moves going forward:

-re-fill the pool
-order test kit (look in my siggy below for where to get the TF-100. I would get the XL version
-Look in my siggy for the recommended chemicals link. That will tell you what we use in our pools. Do NOT go buy everything on the list as you will not need all of it yet or ever.

Chlorine has to be PLAIN. Clorox has started adding "chlor max" or something like that to their chlorine :( this has caused some foaming in the past. Find PLAIN chlorine or bleach. Your pool store might sell it in re-fillable jugs. Do NOT buy anything else from them.

That should get you started on the right path.

Kim:kim:
 

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NewB77777

Active member
Dec 1, 2019
36
Los Angeles
Chlorine has to be PLAIN. Clorox has started adding "chlor max" or something like that to their chlorine :( this has caused some foaming in the past
Because I already emptied pool, foaming is okay for me. I will drain it again after cleaning.
I guess Clorox that I can buy HD is cheaper than chlorine. So If Clorox clean good, then I think Clorox is good for me.

And I can't find liquid chlorine from Leslie's pool. (Pool Chlorine & Pool Shock)

Below are the ones that I found.
Please let me know which one is the best.


In case I use pressure washer to clean wall and bottom of pool, do I need to use detergent(like BE 85.490.052 Semi-Pro Deck & Fence Pressure Washer Detergent Concentrate 1 Gallon) or Simple green, or just water is fine?

And for black algae, I don't need to use any other strong chemical like Acid to kill it, right?
I just need to brush hard with chlorine, and refill water and maintain chemical. Am I right?

Thank you.
 
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Rancho Cost-a-Lotta

Silver Supporter
Apr 10, 2018
831
Rancho Cucamonga, CA
You probably won't find the HDX 3-pack in-store, but you should find the two-packs of 10% liquid for about $7.00. It comparable to the Kem-Tek stuff in your Lowes link above. Check you local independent pool stores (not Leslie's). They may carry "HASA" 12.5% liquid in refillable containers for about $4.00 per gallon.
 
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NewB77777

Active member
Dec 1, 2019
36
Los Angeles
I got 2000 psi pressure washwer with detergent, and I'm cleaning with it.
It works. However it takes more than what I expected.
Is 2000 psi good(not too high, not too low)?
I think it will be faster if I use 3000 psi.

I finished one side wall, and poured bleach that I got from Leslie.
it is stronger.. so I though it might good to kill algae..

BTW, do I have to wear mask when I use bleach?
I got 3M mask from Ace hardware( 3M R8730B Bleach Odor Respirator, Non-Valved, Disposable Respirator - Papr Safety Respirators - Amazon.com)
I paid more than $4x. It is way expensive.
So If it is not very necessary, then I'm going to return, and will order on Amazon.

I will update pool once I finish the job.

By the way, I heard there will be rain tomorrow.
Can I use rain water for pool?
Is there something that I need to do before raining?
I might not able to finish cleaning before raining.

BTW,
Leslie employee told me that Acid is too strong so that it will damage plaster.
So he suggested to use chlorine to kill algae.
Not sure it is right or not.
Thanks.
 

jimbethesda

Gold Supporter
Jul 2, 2018
238
Austin, TX
DO NOT PROCEED UNTIL AN EXPERT HAS CHIMED IN!

I think they meant for you to refill first, then SLAM. They also told you not to pressure wash it. I’m not sure it’s a good idea to put bleach directly on your plaster, but again, let an expert say that.
 

JJ_Tex

Bronze Supporter
Jul 17, 2019
447
Prosper, TX (DFW)
So, I watched the video and they poured bleach on the plaster, hosed it off, then quickly filled it back up. I would have done that and avoided the power washer that can rough up your plaster and cause issues down the road. You also had lots of advice above not to power wash.

Whatever you decide to do, I would try and wrap it up today and get it filling before it rains tomorrow, as the rain will increase the chances of it popping out of the ground and making an even bigger mess.
 
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NewB77777

Active member
Dec 1, 2019
36
Los Angeles
I already asked two pool guys, and I asked them what they are going to do.
And they told me that they are going to use pressure washer with other chemical to clean.
I went to Leslie, and I asked about cleaning and killing black algae.
And I saw couple of videos, and read some articles, and I asked questions here too.
The solutions that I got from above sources are little different, so I'm little bit confusing.

Anyhow, I almost finished to clean.
I used pressure washer with detergent to clean first, and I poured chlorine liquid alongside wall, and wash it again.
I scrap black algae, and applied chorine liquid on there. Not sure it was effective or not.
Please see my pictures, and let me know if it is okay to fill water up again.

BTW, I opened a lamp, and I found couple of insects and some kind of mud in there.
Before filling water, I want to clean inside.
Can I remove the mud kind thing, or it should be there, or do I have to seal it with silicon thing.

The most important thing for now is black algae.
And I think it might easier to kill it before filling up water. (is it or it isn't ?)
Please let me know what I need to do before filling up water.
Thanks.
 

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JJ_Tex

Bronze Supporter
Jul 17, 2019
447
Prosper, TX (DFW)
Looks pretty good to me, but I'm no expert.

Barring any input from the experts, I would:
- wipe out the gunk from the lights and reinstall them
- start filling the pool today/tonight
- Once full, I would maintain an elevated chlorine level for several days to ensure all algae is dead (do you have chlorine and a proper test kit?)

After that I think you need a good game plan of properly testing on a regular basis and maintaining proper levels, mainly chlorine levels. We can help you with that, but lets start with getting water back in the pool.
 
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YippeeSkippy

Mod Squad
LifeTime Supporter
Jan 17, 2012
11,668
Evans, Georgia
WoW.. big improvement. Now, having done the pressure washing bit- did you find any damaged areas of plaster that need attention?

Show us the areas of "black algae" you find. Did you scrape some up on to a card before like I asked you to do?

Have you a stainless steel brush to brush them with some diluted chlorine, and continue such with water in the pool and higher FC for a while?

Maddie :flower:
 
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NewB77777

Active member
Dec 1, 2019
36
Los Angeles
I attached the black algae pictures. Not sure it died or not.
I couldn't find any plasters are damaged.
I didn't do any card thing yet because I'm going to fill up with new water, and anyhow I didn't the card yet from Amazon.
I scrub with metal brush before chlorine because Leslie guy told me I need to use nylon brush with chlorine.
I am going to go Leslie to buy Acid to apply on it because it is good chance to do.

I opened the filter, and saw it is time to change.
Can you let me know the best place to buy it?
And what micron do I have to buy?
I saw Leslie have powder which makes the filter to filter smaller micron.
Does it works?

Thank you.
 

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Rancho Cost-a-Lotta

Silver Supporter
Apr 10, 2018
831
Rancho Cucamonga, CA
Don't pour acid directly onto the pool surface. It will damage the plaster. Chlorine and a scrub brush is the best way to get rid of black algae. Maddie is recommending that you use an index card or white piece of paper to rub the black substance onto. If it leaves a green smudge on the paper, it's algae. Here's a detailed plan of action from Pool School:

 
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