Im sure 6.8 is ment to be runoff for soil not hydro. hydro is ment by be at around 6.
Ah ha found it "You want around 6.0-6.5 for a soilless mix, or 6.3-6.8 for soil."
But that looks similar to what i had when i over neuted them only last week, flushed them through and there on their way getting better now