I am using 2 flouro tubes for vegging, but my buddy just gave me a 250 hps bulb with the socket it screws into. I know i need a ballast but i know nothing about them. Do I need a certain size or watt? Do they all run the same?
you need a ballast that matches the wattage and type of bulb you're using. You need to look for a 250watt hps ballast. For example there are also 400watt hps ballast and 400 watt MH ballast, and so on. I don't know any places that sell just ballast online (it's usually the whole setup with socket, ballast and reflector hood), but your local hydro shop should sell ballast seperate.