I'm sorry that I didn't scroll back through to reread this thread when I asked if you had trichlor or dichlor on hand. With as many posts as we answer in a day, sometimes questions/info gets repeated.

Trichlor will add CYA but will do so slowly. If you want to increase it faster, you are better off using dichlor. For every 10ppm of chlorine that it adds, dichlor will also add 9ppm of CYA

I hope you didn't think I was saying that you aren't staying on top of your chemistry. That was certainly not my intent.

You are right that not having enough CYA will cause chlorine to be lost faster.