HPS bulbs are REALLLY yellow IME. I have a 250 or 400 watt at the house for a flood light, I might try to put it over a tank to see what happens, but if the halide bulbs from lowes are good for algae growing because of color temp, these will grow it over the sides of your tank! Of course I'm really good at being wrong so this may be one of those times... but the lights are yellow!! ;-) Will also add they are GREAT for growing plants, everything from seedlings to fully grown, fruit bearing tomatoes. I've grown tomatoes, broccoli, collard greens (don't worry, I didn't eat them *sound of gagging*), carrots (with limited success due to soil depth requirements), and even grew out some cuttings from peony and rose bushes under HPS.
