Chevron, I also ran 40w NO's over my tank with success, but maintaining corals and making them thrive are 2 different things. When I put my current PC's on my tank, all my corals expanded another 33% and rapidly began reproducing. It truly is something you need to witness on your personal tank before before you realize the difference. PC's are not expensive and the bulbs last 12-14 months instead of 6 months. I would suggest PC's to anybody with a small tank. I was quite upset when I first turned them on because they seemed dull. I was expecting the sun itself to blind me when I flipped the switch, but after 3 days, I could measure an extreme difference.