Algae stains...i think.

[Bluelitening]

Great info on pool stains, I have been reading several pages. My Problem is i just had an algae attack last week in my inground gunite pool with a gray painted surface on top. (I think its tinted gunite) this happened once before. The pool tech guys said to add 2 gallons of muratic acid and two pakages of shock and call us in the morning. pool turned out beautiful we enjoyed the weekend swimming and all was good.
However after this last attack i did the same thing This time I added some algaeside. Everything cleared up great however there are some brownish/yellowish stains in various places on the bottom of my pool. it appears that when the pool shark rolled over the area it picked up and left the pool floor sparkling but these stains appeared to be where the pool shark missed. I tried using the wire brush to remove the stain thinking it would go away but to no avail. it seems to have imbedded itself into the gunite. I dont want to sand paper it. Is there any chemicals I might be able to use? or will it be an Acid wash to get rid of it.
Thanks in advance for your suggestions.

[Helen]

Hi Bluelitening,

With regards to your problem, I suggest that you purchase a water stain kit. These are available from a variety of pool chemical manufacturers. Select the kit from the brand of chemicals you are presently using.
You must first know what kind of stain is that, if it is really an algae stain. You must follow the test kit direction. It may need to be a specific sample or a water sample from any part of the swimming pool. Once you get the diagnosis, you can purchase the chemicals needed. Use the chemicals as directed. If you think it's beyond your skills, you can contact a pool maintenance company to test your water and stain sample.

SOURCE: ehow.com