You need to take care of your water problem first and then let someone address your stain problem.

How recent are your readings? If they were taken before you added pH stabilizer (whatever that is), you need to retest. A pH of 6.1 is a critical problem. Anything below 7.0 is acidic and will damage your pool.

Triclor is very acidic and will drive your pH down. Check the ingredient label on your trichlor. Is copper listed as one of the ingredients? Some trichlor tabs have it and we do NOT recommend that you use it.

What product have you used to shock with? How high have your shocked? With your CC reading and low FC reading, you need to shock your pool up to about 12ppm and try and hold it there. I suggest you just use plain, unscented household bleach. Generic from Walmart is just fine. Each quart of 6% bleach will add about 1.2ppm of chlorine to your pool. Test a couple of times a day and each time, add enough bleach to bring it back up to 12. Also, run your pump 24/7 right now. You also need to get a good test kit so you don't have to rely on the pool store. We suggest the Taylor K-2006 or 2006C which is the same kit with larger quantities of some of the reagents.

I would also suggest you do some reading on our sister website poolsolutions.com as there is a lot of good information that will help you.

By the way, what type and size of pump do you have?