Black Stain In The Deep End

I have a stain in the deep end. I got the pool built 7 months ago and never had any stains. Now I have a stain that started about 3/16 inches round and appeared to be rust.


Now the stain is about 1 1/2 inches and has some rust around it that comes off with no problem except now it has a black stain that will not come off.

How do I remove it?




Thanks for the question

First, I'd like to have your complete chemical readings, the actual numbers:

Chlorine, CYA (cyanuric acid/stabilizer), pH, Alkalinity, Calcium Hardness, and Metals (iron and copper) and names of any algaecides you may have used along with clarifiers, phosphate removers, and/or flocs. It makes troubleshooting much easier .

Next is you need to determine the kind of stain it is, whether metal or organic. Get a chlorine tab and put it on an affected area for about 2 minutes. If it lightens up it's organic and you'll need to shock.

If it doesn't lighten up or gets darker you'll need to get some crushed up ascorbic acid (Vitamin C). Put about 1/2 lb. in a sock and place it on an affected are. If it lightens up it's a metal stain and you'll need to do an ascorbic acid treatment.

Also, is it an inground vinyl or above ground pool? With an aboveground pool you may have rust coming through the bottom or perhaps bacteria or mold.

Vinyl Liner Has Dark Stains On Bottom

If it's plaster you can still do the tests above. As you can see there are some variables that need to be considered before you attack the issue correctly.
I hope this has answered your question to your satisfaction.

To post a reply, or if you have a similar question, you can see your post on the Q&A page in the "Black Algae" category.

Check back to this post for updates or answers.

If you feel your situation is more complex and want immediate assistance (within 24 hrs) you can make a donation of your choice and I'll answer your questions by phone.

Have I helped you find a solution to your pool problems? Did this information help you? Please consider making a donation to help keep this site going. Thank you.









Have a great Summer.

Robert

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Black Algae

by Richard
(Oxnard, Ca)

My question is I think my pool has black algae. I am going to do the chlorine tablet test to find this out.

If it is, do I need to drain my whole pool to scrape and scrub, or can I leave the water in and do this. Will it cause me any harm or skin any harm if I do this with the water in.

Thank you




Thanks for the question Richard

No you don't need to drain the pool but it does make it a bit easier to scrape the heads off the black algae.

You can get a tool called Algae Gon tablet holder. Place the tab in the slot and rub the affected areas. Then use a stiff wire brush over the areas. You're not going to completely get rid of the algae because it digs into the plaster. You're just scraping off the top layer.

Next is get some Trichlor powder. Turn the system off and spread the Trichlor around the areas. You don't need to pile it on, just a thin layer will do. Allow this to sit for 24 - 36 hours, then turn the system on FILTER for 24 hours.

You also want to keep the chlorine level 3.0ppm or above to lessen the effects of the black algae.

Don't rush this process. It takes time and patience to do the job right.

I hope this has answered your question to your satisfaction.

To post a reply, or if you have a similar question, you can see your post on the Q&A page in the "Black Algae" category.

Check back to this post for updates or answers.

If you feel your situation is more complex and want immediate assistance (within 24 hrs) you can make a donation of $29 per hour and I'll answer your questions by phone.

Have I helped you find a solution to your pool problems? Did this information help you? Please consider making a donation to help keep this site going. Thank you.









Have a great Summer.

Robert

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I Have Black Something On My Pool Liner?

by Teena
(Iowa)

I have a inground pool. This spring when the pool guy came to open it, it was lake dirty water, with a rotten egg smell.

After a lot of waste vacuuming the water has cleared up to cloudy and we can see the main drain in the 9 foot deep end.

BUT, I am also left with about a 10-12inch jet black ring around the pool where the bottom meets the sides. It goes continuously around my pool. It looks like someone just decided to paint a pretty black line around the pool.

I have spent the last 5 days brushing the sides of the pool and putting pool shock in the pool with nothing happening. I have been keeping my chlorine level very high, with this and also the ph and alkalinity have been also on the high end of the stick. Is this black algae or is it something called pool tar?

How am I suppose to treat this and what is this? Any help or advise would be greatly appreciated.




Thanks for the question Teena

I'd like to have your complete chemical readings, the actual numbers:

Chlorine, CYA (cyanuric acid/stabilizer), pH, Alkalinity, Calcium Hardness, and Metals (iron and copper) and names of any algaecides you may have used along with clarifiers, phosphate removers, and/or flocs. It makes troubleshooting much easier and the process of clearing up your pool will go much faster.

Do you have a vinyl liner? If you do and you used a cheaper kind of algaecide (copper/metal based) during the start-up procedure, it could be pool goo or pool tar. You can go to these links to find out more:

Sticky Pool Algaecide On Vinyl Liner

Help With Black Like Tar In My Pool

If you have a plaster or concrete pool, it could be black algae. A simple test can confirm this. Take a chlorine tab and put it on an affected area for about 2 - 3 minutes. If it lightens up it's black algae. If it doesn't lighten up or gets darker it's probably metal stains. Are you on well water?

Black algae is very difficult to get rid of. It digs into the plaster. You really only scrape the heads off the algae. The roots remain in the plaster.

A high pH, above 8.0, along with a high TA can render the chlorine less effective. You need to get the pH and TA in line for the chlorine to work effectively. The ranges are 7.4 - 7.8 and 80 - 100ppm. For shocking a pool at start-up you'll want to get the pH down to 7.0.

Shocking is a process, not an event. The trick is to get AND keep the chlorine above 10 - 12ppm for a period of time. You'll need to manually dose the pool with chlorine to keep it at 10 - 12ppm. Make the adjustment at night, then retest in the morning.

Get back to me with the numbers and I'm sure I can help.

To post a reply, or if you have a similar question, you can see your post on the Q&A page in the "Black Algae" category.

Check back to this post for updates or answers.

If you feel your situation is more complex and want immediate assistance (within 24 hrs) you can make a donation of your choice and I'll answer your questions by phone.

Have I helped you find a solution to your pool problems? Did this information help you? Please consider making a donation to help keep this site going. Thank you.









Have a great Summer.

Robert

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That Damn Black Algae

by Al
(Clearlake, CA )

I have a 16 x 32 above groung doughboy pool. Until 2 weeks agon no problems....and then black spots appeared.

I have kept the cl2 levels above 5ppm and have a sand filter. The ph was 7.4 or higher so I added PH down...now 6.0/7.0.

Consulting with two "pool experts?" I have added 4 quarts of Hasa - cide. I did this over a three day period to little or no avail.

One "expert?" suggested....love this...change the liner.

Sites I have searched say a copper algaecide is needed.

Please help....my grand children are wanting to get back in the pool.

Today, within the hour I added 6 gallons of 12% cl2.




Thanks for the question Al

Black algae on a vinyl pool liner is uncommon. It can happen, but it's uncommon. You need to confirm that it is in fact black algae. If you don't do this, you'll be spending lots of time and money wondering what's going on.

Take a chlorine tab and put it in a sock, then hold the sock on the black spot for about 20 minutes. Use a telescopic pool pole if you have one, not your hand. If it fades or turns gray, it's black algae or some other kind of organic stain.

If it doesn't fade, take a sock filled with about 1/2 pound of ascorbic acid (crushed up Vitamin C). Put this on the spot. If it fades, it's a mineral problem and will only be solved with an ascorbic acid treatment.

Here's the ascorbic acid treatment protocol:

Brown Algae Won't Come Off Of A Vinyl Liner

Here's a post about stains coming from under a liner:

Vinyl Liner Has Dark Stains On Bottom

And the black algae page:

Black Algae

Black algae is more common in plaster pools because it seems to attach itself to the plaster. It really can't do this with a vinyl liner.

An algaecide is used for preventative maintenance only, it's not used to get rid of already existing algae. The only thing that can get rid of existing algae is a good pool shock.

Swimming Pool Chlorine

Pool Shock

Pool Chlorine

Chlorine Tablets

Pool Chlorine Tablets

You also need to have a good pool test kit. I still use and recommend a Taylor FAS-DPD K-2006 test kit:

Pool Water Testing

Water Testing Kit

And the statement about using a copper algaecide, read this post. It may change your mind:

Sticky Pool Algaecide On Vinyl Liner

If anything, you'll want to use a PolyQuat 60 algaecide. This contains no copper or metals.

Try the chlorine tab and ascorbic acid test and let me know how it turns out for you.

To post a reply, or if you have a similar question, you can see your post on the Q&A page in the "Black Algae" category.

Swimming Pool Questions and Answers

Check back to this post for answers and updates.

Hope this helps and have a great Summer.

Robert

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