I have metal halide for a 30 gallon high planted tank. I use two computer fans on the bulb, and one computer fan on the ballast. The bill is not that bad. The heat and the noise from the fans are my concern. It took a few different fans to balance the noise from the fans to the heat from the bulb. However, it's worth. I love planted aquariums. So, I have a planted tank with discus, angels and rams. The fish seem really happy and healthy. I think they grow faster also because of the added nutrients the fish get from the plants and protozoa. I tried led and fluorescents. The plants grow better under metal halide. Their are precautions with metal halide, but they are the best aquarium light.