Black Stain! Help!

bryantdr

Well-known member
Jul 21, 2015
60
Long Island, NY
Sorry for the dramatics, but we just moved into a new house that has a 44k gallon liner chlorine pool. The pool seemed to be running well for a few weeks, and then yesterday I noticed a pretty big black stain in the bottom of the shallow end (3 or 4 feet in size). From reading these posts I figured it was either black algae or some sort of stain. The previous owner had a pool guy who had been using tri-clor in a feeder and who know what else (I shut off the feeder). I'm not great at reading CYA but I'm guessing it is in the 100 range, so I've been keeping my FC levels in the 8 to 10 range with liquid chlorine and hypo cal. Instead of draining the pool, I was hoping to let the CYA come down over time with splash out, and small leaks.

Thinking it could be Black Algae I slammed the pool last night up to 30 FC. Here were my pool stats before the slam, and the water is clear
PH 7.8
FC: 10
CC: 0.5
Calcium: 40
CYA: ~100 (not great at reading this test)
TA: 60

This morning the black stain was twice as big. Picture attached. It's in the shallow end near, but not directly under a waterfall from the hot tub (hasn't been heated recently).

Reading some other threads I took my water to be tested at the pool store, and they said there was no Copper or Iron in the water, and Total Dissolved Solids was 400, and Phosphates were 200.

I have been scrubbing the area with my standard nylon brush, and can't tell it is making a difference. I also went it last night and tried to scrub the area with a puck, but I couldn't tell that it made a difference either.

The only things that have changed recently are:
1. We have had landscapers doing a lot of pruning around the pool the day before. A lot fell in the water, but I think I got it all out.
2. We turned on a slide, which hadn't been used in awhile, and may have had some stagnant water
3. I recently started using the Cal-Hypo (I know it's not part of the protocol, but I didn't realize this could cause a staining issue, and my Calcium was so low I didn't think it could be an issue for years).

The pool store guy wasn't sure if it was black algae or a stain but said to get some vitamin C tabs and put them in a sock and scrub the stain, because ascorbic acid is great at getting rid of stains. I haven't tried it yet, and I wanted to check with the forum.

Any thoughts or help would be greatly appreciated! By the way, the white you see in the left of the picture is Cal-Hypo sitting on the bottom, which obviously isn't doing anything to break up the stain



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JamesW

TFP Expert
Mar 2, 2011
17,374
Probably copper stains triggered by the calcium hypochlorite.

I don't have any confidence in the tests from the pool store.

Copper could have come from the heater if the pH was allowed to get too low, which it likely did with trichlor.

Copper could have come from algaecide, which I suspect was probably used.

Copper could also have come from an ionizer if you have one.

Probably not much that you can do other than replace the liner.

You can try Jack's magic #2 sulfamic acid, but it might not work and the copper would still be in the water and it would probably restain anyway.
 

bryantdr

Well-known member
Jul 21, 2015
60
Long Island, NY
Probably copper stains triggered by the calcium hypochlorite.

I don't have any confidence in the tests from the pool store.

Copper could have come from the heater if the pH was allowed to get too low, which it likely did with trichlor.

Copper could have come from algaecide, which I suspect was probably used.

Copper could also have come from an ionizer if you have one.

Probably not much that you can do other than replace the liner.

You can try Jack's magic #2 sulfamic acid, but it might not work and the copper would still be in the water and it would probably restain anyway.
Thanks, so the Ascorbic Acid wouldn't help? Would it help to take this to a different pool store and see if there is copper in the water. How would I know if I have an ionizer? The water has 0 calcium where i am.
 

Donldson

TFP Expert
LifeTime Supporter
In The Industry
Jun 12, 2009
3,970
NW Ohio
I agree with James. Algae on a vinyl liner would brush away and an organic stain doesn't form overnight and would have shown a reaction to the puck.

Ascorbic acid doesn't remove copper, it causes it to get darker which for that stain probably wouldn't be noticeable. Pool store guy should know this. If you want to confirm to yourself that it isn't iron though go ahead and try it. It would be better than taking it to another pool store, IMO.
 

JamesW

TFP Expert
Mar 2, 2011
17,374
I wouldn't worry about a copper test. I'm really pretty sure that it's what you have.

You can try ascorbic acid to see if it does anything.

Sulfamic acid would be the most effective.

Sulfamic acid would lock up the chlorine for a month or two. You would have combined chlorine which makes it more complicated to manage

Even if it works, the copper is in the water and it can restain at any time.

Using sequestrants and careful chemistry management might get you a few months without copper stains.

Definitely get the calcium hypochlorite off of the floor and I would stop using it altogether.

All water has calcium. Have you tested the calcium hardness?

Do you have a picture of the system?
 

bryantdr

Well-known member
Jul 21, 2015
60
Long Island, NY
I need a better wide angle shot, but here is a lot of the pool equipment. Actually someone left a bottle of Copper 7 back there, so I guess that makes sense that it is in the water. It also looks like there is maybe a salt water generator hooked up, but it could be an ionizer. They definately weren't using the SWG, as it seems they were relying on the puck feeder. I'll try to send some better pictures tonight. We haven't been using the heater, but not sure if water flows through it anyway.



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JamesW

TFP Expert
Mar 2, 2011
17,374
The cell is pretty old, so probably dead. The stain is almost definitely copper. Where's the puck feeder?
Try ascorbic acid on the stain.
 

bryantdr

Well-known member
Jul 21, 2015
60
Long Island, NY
The puck feeder is off to the right of the picture I posted. Here is a picture.

Question from the comments above. Is it possible the pool store is saying I have 0 copper, because it all got used up in this stain, and if I treated the stain I might not be in bad shape for it coming back?

Are there any alternatives to Jack #2. Based on the size of my pool, and the other recommended products (Jack's Blue), this looked like a $500+ treatment.


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JamesW

TFP Expert
Mar 2, 2011
17,374
Copper is in the water. Not much you can do about it other than drain and refill, which usually means replacing the liner.

Try ascorbic acid on the stain. It might work. Drop some vitamin c tablets to see what happens.

Jack's #2 might work but the copper doesn't go away, it's still in the water.
 

bryantdr

Well-known member
Jul 21, 2015
60
Long Island, NY
Has anyone had any success with Jack's Vinyl Liner Blue Stuff. It says it can remove copper stains, and doesn't look like it involves as intensive protocols as Jacks' #2
 

bryantdr

Well-known member
Jul 21, 2015
60
Long Island, NY
So some progress. I added a gallon of half strength muriatic acid knowing the PH was on the high side: 7.8 before I slammed, and most of the remedies require low ph.

Then I filled a sock with vitamin c pills, tried to smash then up a bit, and scrubbed the black stain, and when that was empty just dropped vitamin c pills on the spot.

I will take another picture in the morning, but I think it is working. When I move the pills around with the brush, it looks like they left clear spots behind them.

Assuming this actually works to completely remove the stain, I have a few questions.
1. Does this mean it was iron and not copper, or just that copper is easier to remove when it is fresh?
2. Does it make sense to use one of the magic Jack's maintenance products to try to prevent restaining?

This evening before I started FC was down from 30 to 18. I'm guessing it will keep coming down with the asorbic acid.
 

bryantdr

Well-known member
Jul 21, 2015
60
Long Island, NY
In my opinion, it's copper. I would try the ascorbic acid. Sequestrant can help reduce future staining.
Here is a picture from this morning. I put 3 lbs or so of vitam c tablets on it last night, and then I shifted them around for a few hours.

It looks like the stain completely lifted from where it was, but a lighter green stain formed further down the pool. Maybe it lifted and drifted.

I had the pump off last night so the asorbic acid could sit. The water wasn't circulating, but this morning in the deep end
FC was about 1
CC 0.5
PH 7 or less

I ordered more asorbic acid and the Jack's blue for liners, but they won't get here until later in the week.

Questions, is it fine to turn the pump back on and put in the pool cleaner?

Given the progress I made, I figure it would be good to keep hitting it with asorbic acid.

Is there anything I need to keep in mind, i.e. don't let the water get took acidic, or how long i can go at low chlorine levels, or any other advice on next steps?
 

bryantdr

Well-known member
Jul 21, 2015
60
Long Island, NY
Here is a picture from this morning. I put 3 lbs or so of vitam c tablets on it last night, and then I shifted them around for a few hours.

It looks like the stain completely lifted from where it was, but a lighter green stain formed further down the pool. Maybe it lifted and drifted.

I had the pump off last night so the asorbic acid could sit. The water wasn't circulating, but this morning in the deep end
FC was about 1
CC 0.5
PH 7 or less

I ordered more asorbic acid and the Jack's blue for liners, but they won't get here until later in the week.

Questions, is it fine to turn the pump back on and put in the pool cleaner?

Given the progress I made, I figure it would be good to keep hitting it with asorbic acid.

Is there anything I need to keep in mind, i.e. don't let the water get took acidic, or how long i can go at low chlorine levels, or any other advice on next steps?
Here are before and after pictures of the big black spot before i started treatment, and then the lifted and shifted spot this morning
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JamesW

TFP Expert
Mar 2, 2011
17,374
Clean the filter and begin circulating. You can use the cleaner.

I would complete the ascorbic acid treatment today.

Get some locally if necessary. Natural Chemistry Extra Strength Stain Free is ascorbic acid.

Extra strength, not regular Stain Free.

Add sequestrant and then 2 quarts of Poly 60 algaecide. Poly[oxyethylene(dimethyliminio)ethylene(dimethyliminio)ethylene dichloride] 60%. No other ingredients.
Wait 1 hour between additions.

Then, begin to slowly increase the chlorine to normal levels and maintain as needed.

The liner is damaged and you're probably not going to get it back to a like new look.

You're lucky that you were able to get the results you got so far because copper doesn't respond well to treatment.

It's not clear what is causing the remaining stains. It might be copper or other metals.

Maybe silver or iron or something else. No way to tell without knowing the history of the pool.

Don't use calcium hypochlorite.

The metals are in the water and they can stain anywhere at any time.
 
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bryantdr

Well-known member
Jul 21, 2015
60
Long Island, NY
Thanks a lot. Just to run through order of events so I'm clear.

  1. I turned my filter on and ran the Dolphin before I left. Unfortunately it's a cartridge filter, so it's more of an undertaking to clean than I could do this morning before work. I'll try this evening if it isn't raining too hard.
  2. Whether it's more vitamin C tablets, or finding a local source of pure asorbic acid, I'm going to add more tonight. Does 4 lbs sound right? It looks like it's cheapest to just get the vitamin C tablets, and put them in the blender, vs. the stuff from the pool store, unless you think that stuff is better.
    1. Should I run the filter when I add the Asorbic Acid, or try to let it sit on the stain?
  3. On Thursday evening I have the Jack's Blue arriving. Is it too late to wait until Thursday evening to add the Sequestrant and then the Poly?
    1. Could I add the Sequestrant tonight either before or after the Asorbic acid, or should I wait until Wednesday night
  4. I assume the Natural Chemistry Metal Free and Poly 60 Algae Control would work too as locally sourced brands?
  5. After adding the Poly 60, I'll start taking up the chlorine with liquid chlorine. Maybe try to increase it 2 ppm per day?
  6. At what rate, and when should I start taking up my PH?
I'm fine that the filter will never look "like new" again. It was pretty faded when we bought the house a few months ago, and had mismatched stairs from a repair. I just don't want a scary black or green stain that makes guest not want to go in our pool

Thanks for all the help!
 
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