JWB:

Let's make it very clear: Too high chlorine can make your pH look HIGHER than it is, not lower.

Your pH was a very LOW 6.8--therefore if the chlorine had given it a false high reading, I SHUDDER to think how low it really is--probably around 6 or the high 5's.

In either case I'd be adding Borax--at least a full box at a time to raise that pH.