indoor newbie concerns

Why use so many veg. and fllower ferts.? Can I use a MH for flowering, or a HPS for veg.?

I dont understand the text in front of the first question mark, so I'll skip to the second.

You can use a MH for flowering or a HPS for veg, it just wont work as well as doing the opposite. Some people like to use both lights at the same time for flowering. Most just do T5 flouros for cloning/germination, MH for veg, and HPS for flower.

The first question was why use five different fertilizers for vegative state, then use another five for flowering. Couldn't I just use grow big and big bloom ?

nah man the ferts are specifically designed for each stage of the plants life cycle. nuts are measured as NITROGEN-PHOSPHORUS-POTASSIUM(macronutrients). during veg your plants enjoys nitrogen for nice green full leaves and stem growth. when you flowering your plant needs the extra phosphorus and potassium for flower and fruit production, (more importantly the phosphorus.)

To answer your question...yes sloshy.....u can use just grow big and big bloom and it will be just fine. That's the only nutrients I use and I've had great results. I'm using a 400w hps/mh, and I've been able to yield 2-4 oz's per plant with just those ferts.