Well it's been slow going but I have new information. After 8 lbs of Borax, my pH level is around 7.0... not much better. I took a water sample to a pool supply company and they got a TA level of 90. They said that the soda ash turned blue (and didn't dissolve well) because I most likely have high concentrations of copper sulfate in the water. They gave me a sample water bottle and suggested I come back in three days to test for metals. Apparently they have substrates that can work with newly stained vinyl pools. Pretty expensive I bet?.. but I'm desperate to find a solution for my stained liner.

I'm continuing to add diluted Borax through the skimmer and also brushing the blue soda ash off the bottom. I'm not sure why the pH isn't rising faster given the amount of ash being circulated in the pool? I hope I'm doing this right.

Thanks for your help and interest.