I think most people have their pH drift up rather than down. However, you might want to start it even a bit lower. I like to start about 5.5 and then let it drift up. Mn is not even available to the plant at all at 5.7.
They do drift up if "the drift" is being done properly. If you start drifting down (fast over 24 hours) then the plant is not eating, most likely things are working on locking out and your food is too high and needs to be lowered. If it drifts up too fast, then your plant is hungry and you need to bring your PPM's up.
Drifting up is good.. drifting down, not so good. 5.7 should be a good start point if your PPM's are on point and your plant is eating :aok:
*disclaimer*
This is all my humble opinion
10-4 guys!! thanks so much, I will be posting pics again tonight, things have exploded overnight with the rez change.