Need help with FOXFARM hydro schedule for NFT. First hydro grow

I just need some general information on how to use a hydroponic system.i just recently built an nft system which holds 8 plants and has an 18 gallon resovoir. Im also using a reverse osmosis filter for my water. will i need an extra nutrient mix because of my RO filter? I already had my big bloom and tiger bloom and grow big for soil so i just went and bought grow big for hydro to save on buying a new nutrient set.

i also need to know how to maintain this nft system. like how often to add nutes and how often to change them. also what kind of ph level should i maintain.

im still kinda new to this and i need some help. my first harvest in soil was successful but their were problems with my girls so im not sure im doing this right
any help would be greatly appreciated

is there anyone that has some kind of knowledge of any of the questions i have?? like just any of them at all im open to all suggestions