Quote Originally Posted by hausfrau View Post
I have posted on this site before regarding my new pool.
1. after two weeks of operation white plaster started to have full coverage mottled stain. It is light brown to green to black. Worse in some areas..better in others (like top step of pool.)
2. Does not rub off, scrub off, come off under fingernail.
3. Is not moved by chlorine or bleach - yes I got the test kit from Amazon and did follow directions from this site to keep a high chlorine level for three days. Nata.
4. Now, it WILL come off if sprayed with a very light mix of 10% m acid and water. But comes back. Only tested this in the hot tub area.
5. Pool store stumped.
6. Pool guy stumped.
7. Pool builder stumped.
8. No it is not metals. Had feeder water and pool water tested. 0.2 for copper. That is all.
9. Water looks lovely and has always been perfectly clear.
10. I hate this pool and am very upset I paid to have this green monster installed into my yard. What should have been a joy is a constant cause of stress.

My new idea - the gunite sat there curing while we were in full swing of pollen from the trees. If the plaster folks had not washed the gunite off properly - since this pool is under Live Oak trees, is it possible I am seeing minerals leaching from the gunite that can cause stains which are almost impossible to remove?
Your description of the stain is either copper or algae. You reported that a vitamin c and RUBBING removed it. Vitamin c works on metal stains chemically so no rubbing is needed. I asked you to hold a trichlor tablet on a stained area and report what happens. You did not. That would be a diagnostic test for organics and/or algae. The colors you describe sound more like algae than mineral (metal) stains. Pollen floats so it would stain your waterline but not the underwater areas of the pool. It is possible that you have "black algae" which is algae that grows into the plaster and is very difficult to remove. It usually gets its start under conditions where the FC is not maintained high enough for the CYA and your daughter's pool party that seems to start this problem is a red flag for this.

Please post a full set of test results and let us see what the water conditions in your pool are right now. You should be posting test results in every one of your posts so we can monitor the changes in your water chemistry as you try and deal with the problem.
Without that info there is not much we can really do for you.

You have posted no test results here and only one set in your other thread here:
http://www.poolforum.com/pf2/showthread.php?t=9970