Ok i am currently using a 40 watt lamp. Would it be a good idea to switch it to a 500 watt lamp when i am home next to them....and switch back when im not???
40W isn't enough light to grow one decent plant, much less multiple. You should be using the 500W exclusively. You'll need to figure out a cooling strategy. You didn't provide any specifics about your grow space, so more info is needed in order for me to advise.
You need 100W for one plant. You're not going to grow shit with 60W. You'll end up with a stretched plant that will not yield much at all. If you want to continue with your current conditions, best of luck to you. Peace.
if your going for high pressure you should opt for like a 150 HPS... but you would need the ballast and wire and shit...... that one you put up would probably need a ballast as well......
do you have a thermometer in your room>???? how big is your closet?
It might even be better to get a bathroom fixture with 4 or more sockets. You could then buy a bunch of CFL's that are around 24W(bulbs are less than $1 each). You might even be able to find a cheap floor lamp with 4-5 sockets for well under $25. Getting a 150W HPS would be even better, but it'll cost more and it will probably run hotter than the CFL's. Be sure and get a good thermometer too. Anything hotter than 85 degrees in that closet with the light(s) on is cause for concern.