What is a ballast for? Difference between these two cool tubes?

[islandhigh]

This one includes a ballast and is tube shaped:$145
http://www.amazon.com/gp/product/B004HNPGKA/ref=ox_sc_act_title_1?ie=UTF8&m=A325274ZEF9XYZ

This one doesnt have a ballast, looks like it reflects more light and is $99
http://www.amazon.com/LED-Wholesalers-GYO2501-Hydroponic-Reflector/dp/B0043CQQTA/ref=sr_1_3?ie=UTF8&qid=1319068483&sr=8-3


I just have a small grow tent: 36"x20"x5'. Which one would suit my needs?

 

[Nusky]

the ballast is the power supply for the light. Go for the first one.

 

[Jack Harer]

The first one is a complete light set up, the second one is just a reflector/hood..........no light.

 

[islandhigh]

The first one is a complete light set up, the second one is just a reflector/hood..........no light.

Thanks. If I bought a bulb it wouldnt just work with the second one? I'd still need to buy the power supply too?

I guess Im just confused as to why one has a power supply and the other seems to just plug right into the wall.

 

[Jack Harer]

No, HID lighting requires a ballast for the bulb to work.

 

[Nusky]

the reflecter actually plugs into the ballast and the ballast goes into the wall. Even CFLs and fluros have ballasts. I'm not really sure why they need one, but I assume its because they need to convert the power into something else. Like AC to DC or something.

 

[islandhigh]

No, HID lighting requires a ballast for the bulb to work.

Ah I see now, thanks bro