how big u grow your plants and how big of a space you use are using is what u go by when determining what kind of hydro system you want to go with. there are many different hydro systems to choose from. some are easy some, are not so easy.
deep water culture (dwc) - roots sit in an airated nutrient solution 24/7. you can go with 1 large reservoir to house many plants or a standalone bucket system. all you need is a reservoir, a net pot, hydroton, air pump, air hose, & air stone/stones. i prefer the standalone bucket system myself. when you put multiple plants in one reservoir, they tend to tangle & become difficult to deal with. you also shouldn't put multiple strains in the same reservoir b/c they're nutrient needs will be different.
flood & drain - plants sit in a large tray that gets nutrients pumped into it for a set amount of time. then drained back to the reservoir. most use rockwool as their medium for this type of system. as the rockwool holds lots of water so that the roots have no need to sit in the nutrients 24/7.
ebb & flo - the most common ebb & flo is the multiple bucket system. where there is a large reservoir that pumps nutrients to all the buckets, then back to the reservoir. the roots sit in the nutrients 24/7 with this system as well
top feed - there are many different ways to do this system. the plants sit in a hydro media. the water is pumped into a feeding tube that waters the roots from the top down. the water is then drained away back to the reservoir.
aeroponics - roots are suspended in air & are sprayed with nutrient solution that is then drained away back to the reservoir. this is the most difficult system to run properly. disease is a big problem when not kept 100% sterile. the roots are extremely vulnerable with this system.
