Anyone recognise this?

[imrodee]

Here are some pics of a neighbor's pool. It is a gunite, 15000 gal play pool with some major discoloration. It is a chlorine pool where the owner says he just shocks and adds tablets when the pool store tells him that it needs it. It is between 15 and 18 years old. The brown is mostly on the walls and steps - not so much on the bottom.

Any ideas of where to start? It looks as if the gunite has worn down in places, the discoloration (brown areas) are smooth, the blue areas are sandy (like gunite) as far as I can feel. I took a sample and this is what I found:

PH 8.2
FC 11
CC .5
TC 11.5
TA 100
CH 225
CYA - I'LL GET THIS AFTERNOON - IT WAS DARK AND RAINING (NO SUN)

Thanks!!!

 

[JasonLion]

That looks like metal stains to me, though it is always difficult to tell from a photo

I suggest trying a quick vitamin C test. Hold a regular vitamin C tablet against one of the stained areas for 30 seconds to a minute and see if anything happens. If the stain goes away in that spot it is almost certainly an iron stain and can be removed with an AA treatment.

 

[imrodee]

Thank you! I will do that test tomorrow Jason.

 

[JamesW]

I think that there are also copper stains. If the pool has a gas heater, then that could be the source of copper and/or iron, especially if the tabs are added before the heater. Copper algaecide, or an ionizer are two other possible sources for copper.

The 8.2 pH seems unusual for a tab pool, and I would suspect an error in testing, or that someone had recently added pH up.

I would suspect that the pH has been allowed to go quite low in the past.

 

[imrodee]

I am so sorry that I'm just now getting back to you with an update..

The Vit C test didn't discolor the brown.. The water was so cold I couldn't keep my arm in there much past 30 seconds. When I tried tongs.. well, lets just say, it wasn't a good test. I'll try again tomorrow.

I had added MA the other day to get the PH down some.. it worked

The Owner added "Pool Store Shock" yesterday, I'm not sure how much.
I retested the water -
PH 7.5
TC 15.5
TA 90
CH 300
CYA 50

Water looks clear.. And its around 39 degrees

The pool/spa does have a gas heater if that helps solve the mystery. The brown areas are real smooth, the blue is sandy feeling (like normal gunite.)
Thank you for trying to solve this.

 

[jblizzle]

Put the Vitamin C in a sock and crush it up and then just set it on the stain for awhile ... keep those hands warm

 

[imrodee]

haha! Thanks! I'll do that tomorrow. Just pour the whole bottle (crushed) of Vit C in a sock?

(I'm a Realtor, and my Seller came out and took my picture laying on the deck with my hand in the frigid water. ..... what we don't do! haha! )

 

[jblizzle]

Maybe not the whole bottle, but enough to actually not dissolve immediately and will sit on the stain.

 

[imrodee]

Thanks Jason.. I'll thin socks or pantyhose, weighted down. The stain is also on the steps, so I bet I can get it to stay put.

 

[onBalance]

Is the plaster finish 15 to 18 years old, or has it been replastered within a few years? And when did the dark stains first appear?

 

[JamesW]

I think that the turquoise is probably copper. The gray might also be copper. Try scraping a small section with a smooth, clean, sharp knife to see if the plaster is white underneath the top layer. Don't dig in too deep, just a very thin scrape.

 

[onBalance]

I agree with JamesW. You might try using Potassium Alum. It might work to remove the gray/brown staining if it hasn't been on the plaster surface too long.