NFT Growing, few questions.

Hi,

I have been growing for 6 months, I think I am doing alright getting between 15oz and 20oz per tank of ok quality stuff. I was just hoping somebody could give me a few points to maybe improve yield & quality.

Setup:
Titan Tent - 2m x 2m x 2m
4 x 600W Budget Adjusta Wings
4 x 205GTi NFT Tanks
8" Outake with Carbon Filter
6" Intake Fan
Oscillating Tower Fan

Nutes:
Genesis Formula
Liquid Silcon (Until 2'nd week of flower)
Root a Gen (Until 5th week of flower)

I like using Genesis so don't wanan change basic nutes, but here are my questions...

What would adding an airstone improve? Yeild, Quality, Plant Healthyness, Grow Time??

Is there any kinda of boost I can use?
People suggest PK 13/14, is this safe with Genesis? When should I add it?

People talk about CO2 tablets/gas, How hard is this stuff to use and what does it improve? Yeild, Quality, Plant Healthyness, Grow Time???

Thanks

Dizzy

Dont need air stones in NFT, the roots get all the O2 they need plus more in an NFT system, best hydro system out there IMO. I dont use genesis but i would think you could still use a boost supplement with it like all other nutes, normally add this stuff around week 2 of flower. CO2 tablets are a waste of time but bottle CO2 hooked up to a regulator is a different storey, this when up and running will improve your yeild.