I should probably toss in my endorsement as well. I have 10 of the 10w units and 6 50w arrays (diff but equally cheap driver and very similar array). The 6 50w arrays over my 100g are doing great as are the 10w arrays over each ~9g segment of the divided tank. The lower empty 30g in the picture has a single 10w over it and it's still pretty bright - plenty enough light for a fish only tank though I wouldn't personally try plants with that little light. I actually convinced my LFS to replace their old t12VHOs that were over their planted tanks to the 20w floods and they are loving them also - much brighter and they've considerably dropped the wattage they are running.