Please Help!! I have an under ground pool, that holds 18,000 gallons. The pool liner(vinyl) and steps were white and blue when the pool was opened this spring. About a week ago every surface under the water became stained a brownish/orange color. I have tried brushing without any success.
My test results using the PS233 test kit are:

FC 19
CC .5
TC Dark orange
pH less than 6.8
Alk 0(test tube water turn red without adding any R-0009)
Cal 200
CYA Greater than 100

I shocked the pool 24 hours before getting the above results. I'm currently using chlorine tablets, guess I should have just gone with good old bleach.

Before shocking the pool yesterday I noticed that the stain seem to be disappering in small spots all over the pool. I brushed around the clean spots thinking it would remove the stain, but I was unsuccessful.

Tonight I added 3 lbs of baking soda to try to raise the Alk. SHould I go ahead and add Borax to raise the pH?I guess I will need to replace some the water to lower the CYA, right?

Any Help is greatly appreciated.