Rockwool is not only NOT a pH buffer, it actually screws up your pH if you don't pre-soak it.
Fans of that type are more efficient when they PULL air, not PUSH it. Set your EXHAUST to PULL air from HIGH in the room. LEave the intake passive and unobstructed.

I take it the dirt plants you show are being hand watered and when you go hydro, you will start with clones?