Brown Discoloration on Light Ring

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cedward138

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May 25, 2011
21
Hi all,

My water chemistry went out of whack while I was not paying too much attention to testing, as well as "stationary" pool shark cleaner while waiting for replacement pods, feet and wings.

First signs were black/brown discoloration of the stainless steel light ring and black algae spots particularly on steps and near bottom of walls.
Added algaecide which helped a little for a few days and noticed that the algae started coming back. Added a second dose (making for a years supply according to the manufacturer - in just a couple of weeks.)
Also cleaned out the filter and vacuumed the pool only to note the return of the algae.

Testing showed FC =0, PH =8 etc.
Placing Pool pilot in boost mode generated a "clean cell" warning.

The cell was found to be completely clogged and took several iterations of 4:1 acid to completely clean it.

The water is now balanced, the algae is gone, but the discoloration of the light ring remains.
It is not removed by brushing with a stainless steel brush. Close examination shows it to be brown in color.

Can someone please tell me what is this discoloration and how do I get rid of it.

For what it is worth, the light may be removed from the pool and placed on the deck for testing or treatment if that is considered easier than treating the pool water.

There are also a few brownish patches on the floor of the pool which are rather unsightly given how sparkly the water is right now. I will try to post a picture of those patches later but hope for help with the light ring in the meantime.

Thanks
 
Vitamin C, ascorbic acid, is a reducing agent, which donates an electron to the iron in the stain, if the stain is an iron stain, which allows the iron to go back into solution. It will also work at least some of the time with other metal stains, though most reliably with iron. If the stain goes away, it is most likely an iron stain and can be removed with either a local or whole pool ascorbic acid treatment. If the vitamin C does nothing we know it isn't iron, but otherwise need to start over and try something else.
 
Jason,

Finally got into the pool today and tried the Vitamin C.
I noted a bit of silver showing through after holding the tablet for about a minute.

I then removed the light from the niche and placed it on the deck. It was layer with a chocolate brown coating that was quite adherent.

Considering that you said it was an acid/metal reaction, I tried a bit of muriatic acid diluted about 50% and the coating fizzed and washed off as a black residue.

All the chrome was still there undamaged and is bright and sparkling again.

However, I would still like your ideas on what this was.
The algaecide I overdosed the water with was Lo-Chlor Pool Algicide with copper sulphate Pentahydrate as active ingredient.

The stain on the floor did not respond to the vitamin C. Have pictures but will upload in a subsequent post.
 
Since the acid made it fizz, it was probably a little scaling with some imbedded copper in it. It's common for copper to tarnish black.

Bottom stains are usually tannins from leaves, etc. You can try holding a trichlor tablet on the stain to see if it does anything to lighten it.
 
Somewhat off topic, but using algaecide for an algae bloom seldom works well. You need chlorine...nothing else.

Pool School will get you some good info and then ask lots of questions. :lol:
 
cedward138 said:
I then removed the light from the niche and placed it on the deck. It was layer with a chocolate brown coating that was quite adherent.

Considering that you said it was an acid/metal reaction, I tried a bit of muriatic acid diluted about 50% and the coating fizzed and washed off as a black residue.

All the chrome was still there undamaged and is bright and sparkling again.
Click to expand...

Just a quick bump of this thread to let you all know that the muriatic acid bath did wonders for my gross brown ring that an hour ago I thought was going to need to be replaced. Thank you TFP community!
 
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