I had alot of problems with the speed of rooting clones. I found that if the water temp is between 75-78, they root fastest. If it's less, they go into a stasis and if it's more, the stem rots.
The water when cloning does not have to be PH adjusted as there are no roots to be affected by it. Just using plain ol' tap water seems to be best.

I have a few slabs of rockwool that I will never use again. I've had nothing but horrible luck with them. I would suggest just using hydroten as a medium (red clay pellets or balls.)