why the price difference?

i've been looking n the different sites that people posted for grow lights... and don't really get why the MH is so much cheaper the the HPS... back here in romania they cost the same... about 30 bucks a bulb...

 

the reason is that the HPS can be used for all stages of growth the MH is excellent for vegging but not that good for flowering.So the HPS is the better choice and the retailers know that so they charge more for them

 

MH bulbs give out a blue spectrum, HPS bulbs give out a red spectrum. The blue spectrum is better during veg, it keeps the distance between nods shorter. The red spectrum is better for flower, and you will yeild more with hps. MH bulbs used during flower will give tighter and more resinous buds.

The best option is a mixed spectrum, use both and rotate plants. Also, some more expensive HPS bulbs also give more of a blue spectrum. You get what you pay for.

Also don't go with a cheap ballast. The cheaper ones usually use alot more power and slam the bulbs during startup harder, so you'll need to buy bulbs more often.