Grey stain on pool liner and now ladder

[nikkih10]

Hope that someone can give some advice on our recent pool problem.
About two weeks ago I noticed that 85% of our pool liner was turning a very light shade of grey (a green/grey).
We have had the pool for 15 years now & this has never happened before. The pool has always been low maintenance. I keep it crystal clear every winter & summer.
Basically only need to use Chlorine. Have used some dry acid when required or Alkali increaser if required, but in 15 years that may have totalled 5 times. I also use an algicide every three months or so. One other thing of note, I use dry chlorine, that soaks in water before I throw it in. When any residual flakes land on the stain, it turn it a much darker grey.

The stain has also attached itself to the pool ladder and now the walls of the pool, brushing the bottom of the pool seems to make no difference. I did get a scouring pad & rubbed the ladder, that seemed to get the stain off, but it took a lot of pressure.

I have had the water tested, it said very little chlorine was there & also it needed an alkali boost. I followed the pool shop guys instructions. Still the stain remains. Another pool guy I spoke to had very little idea also.

I'm hoping someone has had the same issues & can let me know the soloution they found. To me it looks like some sort of chemical inbalance.

Thanks

Ian

[Allen G Myerson]

It's probably copper. What are the ingredients in the algaecide that you use? Do you have a heater?

Have the water tested for copper. Put some ascorbic acid on a small test spot and see what effect that has. Try some vinegar on a sponge to see if it will lighten the stain. What are all of your chemical readings?

[nikkih10]

Allen,
the algecide is all gone now, but is a copper sulphate based product. There is no heater in use.
I tested it on Saturday with a test strip, it showed everything was fine, except Satbilser a bit low.

Ian

[Allen G Myerson]

Try the tests that I indicated. You can get ascorbic acid from your local pool store. Example. Or from here. You can put the ascorbic acid in a clean cloth, like a sock, to hold the ascorbic acid on the stain for a little while.

If you can provide the following information, it will help.

Free chlorine
Combined chlorine
pH
Total Alkalinity
Calcium Hardness
Cyanuric acid
Temperature

You really need to get a good test kit, such as the Taylor K-2006. Test strips are not reliable or accurate.
Copper Iron

[Allen G Myerson]

Note: Vitamin C is ascorbic acid. You can crush up a few tabs of vitamin C and use the powder for a spot test.

[nikkih10]

Called into the pool store to get my water tested properly, but his machine was out for repair.

He didn't have any ascorbic acid, as the chemical factory across the road from work didn't.

The pool shop sold me a product to try called Metal Magic, approx $30.
He said to run the filter 8 hours per day for a week to see if this helps, don't back wash during this time.

Will let you know how that goes.

Regards,

Ian

[Allen G Myerson]

Metal Magic is a HEDP (1-Hydroxy Ethylidene-1,1-Diphosphonic Acid) chelating agent. It might help. You might need a reducing agent to fully remove the stains. Crush up some vitamin C tablets and allow the vitamin C powder to sit on a small area of the stain to see what effect it has.

[nikkih10]

Allen,
I have just tried a Vitamin C pill, nothing happened, I took the ladder out of the pool Which is discoloured. When I took it out & now that the pool is crystal clear, the stain is looking more like a a green/brown colour.

I have taken some pictures that I can send you, if you can post an email address, not sure how to post pics here.
The filter ran all day while I was at work, doesn't look like the metal magic has made any difference.

If I scrape some of the coloured material off would a pool tset at the shop show what it is?

Cheers,

Ian

[Allen G Myerson]

You can post the photos at http://photobucket.com/ and then post the link here. The green is almost definitely copper from the algaecide. The brown is probably from iron. Have you had any algae?

If you can provide the following information, it will help.

Free chlorine
Combined chlorine
pH
Total Alkalinity
Calcium Hardness
Cyanuric acid
Copper
Iron
Temperature

Are you able to scrape off the stain? Try some vinegar on a small test spot to see what effect that has.

[nikkih10]

Allen,
test results below. Copper, almost no reading, it was .02, he had to change it to .1 to show a result.

Free chlorine 0
Combined chlorine -1
pH 7.4
Total Alkalinity 68
Calcium Hardness 242
Cyanuric acid 49
Copper .02
Iron -1
Phosphate .2
Total disolved solids 591

My pool right now is crystal clear

The guys said that adding 4kg of Alkalinity increaser & 3.4 ltrs of liquid chlorine is required. I showed him the pics of the pool showing how random the stain is, he didn't feel that the above additions were going to fix this problem.

Any thoughts?, he said he could get a scraping tested at a cost of $100 or so.

Cheers,

Ian

[Allen G Myerson]

Try some vinegar on a small test spot to see what effect that has.

The copper might test low now because most of the metal is now in the form of a stain. Hold off on the alkalinity increaser for now. Add enough liquid chlorine to raise the chlorine to 5.0 ppm. Don't use granular chlorine.

Alkalinity increaser is regular baking soda.

What is the volume of the pool?
Can you post the pictures?

[Allen G Myerson]

There is no heater in use.

Has there ever been a heater, working or not?

[nikkih10]

Allen,
we have never had a pool heater, there is certainly no plumbing to sugest that the previous owner had one either. We have been here for 15 years.

A couple of developments, tonight I had more time to test vinegar, took the ladder out & sprinkled it over it.
After a while the stain just dissapeared where the vinegar had pooled.

Last night I added approx 10 lites of liquid chlorine along with 500ml of Quaternary Amonium compound.

When I got home today the pool looks clearer, almost 50% clearer. the thing that may be misleading is that the water is slightly milky due to the 10 ltrs of Chrlorine.

The filter is running now. I will run it for a few hours, then vacuum tomorrow.

Do you think there will be an eventual chemical solution to this problem? Or will I be in there with a scourer to clear this stuff off the liner.

Regards,

Ian

[Allen G Myerson]

When I got home today the pool looks clearer, almost 50% clearer. The thing that may be misleading is that the water is slightly milky due to the 10 litres of Chlorine.

Your previous posts indicated that the water was crystal clear. Liquid chlorine should not have had an adverse affect on the clarity. The 500 ml of Quaternary Ammonium compound algaecide could cause some foaming. It would have been better to not have added that.

The vinegar test results are a good confirmation of copper/metal staining.

I will write up a post on a chemical procedure that you can use to try to remove the staining. I need to know how many gallons (or liters) your pool is. What are the dimensions of your pool length, width and depth? What type of filter do you have (DE, sand or cartridge)?

[nikkih10]

Our pool is 45,000 litres, and has a sand filter.

Regards,

Ian