[Stan]

Your plants look very good right now. Make sure your rockwool is not sitting in water as GpsFrontier has stated.

I never had any problems using rockwool. I start off my all my Heirloom and regular tomatoes in small rockwool cubes. I then put a small layer of hydroton at the bottom of all the net pots, place the rockwool cubes in and fill it up with hydroton. Maybe because I'm growing aeroponically 15minutes on and 45 minutes off is the reason why. So far every year I've had tons of tomatoes including some that were very big with the Heirlooms.

Here's 2 pics of my Heirlooms.