Actually, you shouldn't see any liner bleaching with those chlorine levels, even with zero CYA. The CYA makes the chlorine sort of "less aggressive" , which is why you have to raise your maintenance chlorine level when you raise your CYA levels. In order to kill off the algae with a CYA of 40, you need to be at a chlorine level of at least 15 ppm, held there as consistently as possible, until the green clears up. I would keep it at 15-17 or so, if you can. Brush the pool after each chlorine addition, and be diligent about it-- and it will clear.

The fact that your DE didn't appear to come back into the pool is a good thing--it means that your filter is doing what it's supposed to do and catching the dead stuff when it goes through.

Janet