Xcrispy how are you mixing the 3 part? The micro always needs to be mixed in first for some reason, I think that they even state this on there sight or else some changes can take place in the nutes. RW as a medium is not what I like for the fact of the PH fluxes.
If you are mixing the 3 part the way I said then I would back the nutes up to about 500 for about 4 or 5 days and if they still are thriving and don't show any new burns then I would go up from there. Depending on res temps and weather or not you have used any other nutes throughout the grow, I can't remember if you were using the Battani then you may have a different bacterial inviron ment in your water that has changed the bacterial system around some and it is amplifying the efficiency of your 3 part so you may be actually be getting about 1400 PPM from your 700 PPM mix and if this is the case it will also throw off the PH. Your PH may even stabilize once you take down the PPM if what I am saying has any baring.
Adieu your cuz Blue
PS. I have a plant right now that is so burnt that you would think that I had been torturing it a little, but it is fattening up so much that I am just letting her ride it out, because I would have to mix a separate batch of nutes for her, and at this point she is producing more than her sister so what can you do...