The purple stylo was just sitting there and then I added the 120 Uv and then it exploded with growth. I just ordered the blue sky and will mount both bars to my ATI 8 bulb. If I did it over again I'd have three bars over my aquarium or two atlantik v4's if money wasn't an issue. The one thing I don't like is that I'm going to have to drill into the ati fixture. Good thing I'm not changing my mind on these bars.