Hey Dran,
I use organic fertilizers from Advanced Nutrients. They have a ton of products. Here are the two I use:
This smells awful, so it's got to be good! Costs about $85.00 Yikes!
This smells worse, so it's got to be even better! Costs about $25.00
Don't ask me why I use these two instead of all their other products. These were recommended to me by a friend who is a longtime grower. I'll try to find out why next time I see him. But let me tell you, my last grow was my best - 12 weeks of flowering, fat trichomes, etc. It was also the most powerful smoke I had ever grown.
Anyway, my friend's out of town on an extended assignment and before he left, he gave me a 1/4 ounce in a jar labelled:
Charlie's Ass-Kickin' Blend
When I got a chance to try it, I was truly humbled. It just blew me away! It took me a day before I even move enough to write him an email thanking him for it (LOL). Just trying to say these work for me and obviously work for my friend.
If money's an issue, just make sure you get a nutrient blend that's suitable for flowering. You can go to a garden center and ask for a flowering mix. Tell them it's for tomatoes you're growing indoors. All flowers require the same mix - "You say tomato, I say marijuana." Try to get something organic.
I know the above nutrients are expensive, but you might to make note of these when your cash flow's better. I would go with a fertilizer that's good for the flowering phase of vegetables (that's why I mentioned tomatoes - if it's safe to use on something you eat, it's safe on something you smoke.)
As far as harshness of the smoke, that's caused from nitrogen in the leaves. Flushing at least a week before your harvest will lessen the amount of residual nitrogen, but the cure is the most important part.