Yes...bring it down.if you're flushing with 5.7 and its coming out 6.5..the ph is even higher...hence you're locking out nutrients-once you get the ph down..give it a bit of time and introduce a milder mix of nutes to begin with..and then watch your girl to see how she responds..Google online, their is a chart that tell you absorption of nutes at different pHs
cheers