I have a 29 also. I believe I'm in the medium maybe medium low but I've had great growth from almost everything I've tried. All I have is a glass top with 2-24" t-8 lights. Each light has it's own fixture as I couldn't for the life of me find a single 30" fixture that holds two t-8s.
I have been looking at the odyssea 24 inch t5 fixture and the the coralife 24inch dual t5 because they are cheaper but i have heard some mixed reviews about them qnd i dont know if they will be strong enough to get me medium light.