I needed new bulbs to replace my burnt out bulbs. I chose these 6 packs because yes they were cheap. The specified color temperature is 6500K. This is more of a daylight lamp so your fish may look a little dull and not very flattering when used in your aquarium. It's not the fault of the bulb, I was expecting a whiter 6500k as this seemed a bit flat in terms of brightness. You will hear a rattling noise in the bulb when you shake it, but it seems to be working fine.