you can use sodium for both, but MH promotes better veg. growth and female ratio. if i was you i would get a 400w switchable ballast so you can use one ballast for both instead of two seperate ballasts. your reflector can take both. i have two 1000w MH w/ cool sun reflectors and check out my growth so far. http://boards.cannabis.com/showthread.php?t=87140