hope i spelled electriction right OK im working with a 400watt MH/HPS switchable ballast and everything but i have a few questions about bulbs and about ballasts not really weed, sorry if the wrong section, But say you buy a 400 watt MH or HPS bulb and its rated in hours (as well as watts and all the lumens and whatnot, if a 1200watt bulb or a 600watt or anything higher last longer? i know a 400 watt ballast only puts out 400watts, but can i get the same intensity and longer bulb life? the reason i ask is the hardware store has 400watt bulbs for cheap cheap, but they dont have any lumen properties for around 1/3 as the price as the hydro store sells the hydro store bulbs are very fancy and shit but from home-depot its a plain-jane white GE box the bulbs seem to look and burn exactly the same, but im still new to HID a wee-bit i have done 2 floro grows though, and im super excited about this one. as always any coments are greatly apreciated and if you took the time to read all of this, and then more time to understand it, your awsome.
Without more info or direct experience, no one here can say. In general you get what you pay for. As for spectrum and such, get whatever info you can off the bulb itself and google it to see if you come up with anything. Personally I would not use a cheap bulb that I could not find info on. Even with just a few plants the street value of my yield is many thousands of dollars, just not worth cutting corners that probably will cost more than they save. Try buying bulbs online, you may get good ones cheaper than your local hydro shop.
A friend picked up a 1000 watt ballast and reflector off of eBay($250) that came with 2 bulbs. We put the oldest-looking one in (which was a GE) and it works great! I have to wear sunglasses in there. I'm sure he'll try to get the best bulbs he can when it comes time for replacement. If some HPS bulbs differ significantly in spectrum, I am not aware of it. I don't want to be posting stuff that is unsourced and possibly wrong, but this is my experience. If you buy a 400 watt GE HPS bulb it will work very well. 90% plus.
Most hps bulbs sold in hydro shops have added blue spectrum. check www.htgsupply.com for good prices and the best customer service.. they have 10% more lumens than "normal" hps bulbs.