ReptiSun and Arcadia are still trustworthy brands from what I've seen. The T5 bulbs provide the best output in large enclosures and the T8 bulbs w/reflective fixtures provide good output in smaller enclosures like your hatchling bins. I have a travel tank that's about that size and just put a T8 across the top at an angle as the diagram in the previous post suggests. You could also try using some fishing line or similar to suspend the fixture from the rack above. The optimal output from a T8 is about 6-8''