Brown Stain on Stairs and Liner

A few days ago, we started developing a brown stain on our vinyl stairs. We were able to clean somewhat with Mr. Clean Eraser but now stain has come back to cover stairs and has migrated to liner. A Vitamin C tablet has virtually no effect. I left a chlorine puck sitting directly on the steps overnight and can see the ring where the puck was sitting, leading me to believe it's an organic of some kind.

I have a picture I can send but it says I cannot post attachments.

Any ideas of what it may be or how to clean would be appreciated.

Inground pool - 16x36, Jandy Aquapure salt generator, Jacuzzi cartridge filter, Pentair Superflow pump, Hayward heat pump

Free Chlorine - 1.2
pH - 7.2
Alkalinity - 90
TDS - 4,200

1. Link to pictures hosted on Picasa, Google+, Google Drive, Flickr, Photobucket, etc using the image button http://www.poolforum.com/pf2/images/...nsertimage.png

2. Put a pile of Vit C tabs on the steps, and see if there's an effect.

3. Was the 'stain' removed by the trichlor tab?

4. Does the 'stain' brush away?

5. What is your CYA (stabilizer) level?

6. Does pouring an entire bottle of 8% bleach on the steps remove the 'stain'?

Sorry it's taken a while to get back on this. We were on vacation and had a family issue.

1. I'll link to picture. https://drive.google.com/?authuser=0&usp=gmail#my-drive
2. Seems to be slight softening if we use vitamin c tablets but it doesn't just disappear.
3. Not directly removed by trichlor tab. I'm not sure if everything around the tab got darker and the covered spot stayed the same but that's what it looks like.
4. Some gets brushed away but some stays and won't come off.
5. CYA 45
6. Didn't use bleach. I used 5 lbs of trichlor shock.

+ Email the picture to me -- poolforum@gmail.com and include the thread number (25292) -- your link isn't an external link.

+ Try piling some Vitamin C tablets on the spot, and then put a glass on top of them, and leave them overnight.

+ Buy a small bottle of Iron Out, and cover several tablespoons of that with another glass overnight.

Posting info from email exchange:

Test results - 7/28/2014:

FC:1.9; CC: 0.3; pH:7.6; TA:140; CH:100; CYA: 42; Salt:3; PO4:200.
Water color:blue; clarity:Clear; odor:No odor; algae:No algae; feel:soft, maybe soapy
Actions:Vacuumed pool, Added chemicals "20 oz. Knock Out Algaecide; 5 lbs. Chlor-Guard Granules"

Equipment:

21k gal 16x36 vinyl rectangle with both solar and safety covers; 3' - 8' depth; Jandy AquaPure SWCG; Jacuzzi 200 filter; Pentair 3/4 HP single speed pump running 24/7; Heat pump and fountain or waterfall.

Pool is in Pittsburgh, PA area. Using Morton pool salt from Walmart.


Pictures:

Steps:

https://lh3.googleusercontent.com/-e...529%2520sm.jpg


Pool cleaner bag, after 24 hours of use.

https://lh5.googleusercontent.com/-N...529%2520sm.JPG

Has tried both ascorbic acid and trichlor tabs, without noticeable effect.

@PoolDoc: Are those enhanced images or directly from the camera?

Direct.

Wow. Looks kinda like iodine antiseptic or rust on an old car.