Gas, are you running your regular pump, the one you've been using, 24-7? Or are you using a smaller pump with less flow?
You've reminded me that I messed up the timer the first time I programmed it, and the pump ran for at least 12 hours. I had the same kind of root growth you're experiencing. I've linked to this before, but I wonder if drip fertigation, ( constant ) has its advantages ...