A 30 gallon tub would be great. I'm a little limited on height which is why I went with a lower profile reservoir.
I use rockwool as that is what I originally started with and it's worked well. I started with 4" cubes but prefer the 6" for stability and I'll flood those twice per day. I'll flood about 1 hour into flower and about 90 minutes before the lights go out. In veg I'll flood every 12 hours.
I've peeked at your grow journals and I'm not sure I can teach you much.
You're product looks quite impressive! Some mold would appear on the cubes but it was never an issue. I've found that if you have good air flow and elevate the cubes off the tray, even by 1/4 inch, that's enough to make sure they're not sitting in a puddle of water which can cause mold. I've elevated them all with a few 2"x2" ceramic tile pieces. Now if I wasn't such a cheap bastard and bought a proper hydro table, they'd naturally be elevated due to the design of those tables. Another thing I had to purchase was a commercial grade humidifier and that keeps the humidity in check to a point where mold has a hard time living here now.
They work for me. Stick around for their results
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