SJ,
I was keeping the ec around 1.2 with AN sensi two part, rhizo, some cal mg, big bud and bud candy. I am watching SB and Kush now blasting their ABB's with 2.0-2.1, your plants look healthy bro. That pH drop could very well be the plant nearing the end of the pre-flower stretch and wanting the bloom nutes. This one is really unfoldng nicely!!