Five Brown Stains at Deep End - Trichlor and Ascorbic Acid No Change - What Next?

[Michael1]

I have five brown stain at the deep end of the pool ranging in size from 1/2" to 2". I tried scraping trichlor pucks on them and letting it sit until the water dissolved it away. I tried laying trichlor pucks on them for several minutes. I put crushed Vitamin C tablets in a sock on them for 15 minutes. I've brushed them. No change.

What would be the next step?

 

[jblizzle]

Post up a picture so we can see what they look like.
Do they have a different texture than the rest of the pool?

 

[Michael1]

i'll dive in today, and check it out.