I'm going to redo my loop entirely, will probably be using distilled water with a silver coil.
It is indeed, and that why I'm going for a silver coil
They may be able to be reduced a little more, but not much, as far as I'm aware. 4.2 @ 1.28v isn't exactly bad. But once I've redone my loop will spend some more time seeing if I can get i any lower.
Have dropped back to 2.8 atm on 1.05 just to keep temps cool until I redo the loop.