hydro is pretty simple if you have experience with it. most people fail a time or three before they learn the rules and get it right.
some tips for a new water worker:
don't be a dick when asking for advice; most hydro growers spent years in the dirt before braving the water, so they have little patience for people being belligerent while seeking experienced knowledge.
get a tds/ph meter for 15$. you MUST have this until you establish a nute regimen and have used it for a few years. even after, if something goes foul, you'll need it to ascertain the conditions of the bad situation. get and use a tds/ph meter.
keep ph at 5.8-6.0, and don't chase it. most hydroponic nutrients will buffer to 6.0. if you mix your solution and get this after 24 hours, leave it! adding up or down will cause you problems. never chase ph; you'll raise ppms and torture the plants, and have nothing but negative results.
keep water below 68f. if you don't, you will get pythium, and your plants will wilt, get sick, and die. every time.
light proof your buckets. if you don't, you will get algae, which will raise your ph, and cause your plants to become sick, and eventually die. you will also get pythium. see the above statement.
DO NOT try to run 4 plants in a 4 gallon res. you will get bound, ph and tds will go apeshit, your plants will get sick and die. 1 plant per 5g. one 5g plant will fill a 3x3 area if not more, so don't over grow.
DO NOT over grow; too many plants in an area will lead to overlapping, which will create a condition perfect for the propagation of powdery mildew. one bucket per 3x3 area.
change res every seven days, regardless of tds/ph.
top off with fresh water daily.
do not try to detangle roots from the airstone. yes, they will eat it, but you need to leave it until harvest.
make a manifold for your air pump/stones, not one stone per outlet per pump. try it your way if you don't want the advice, and see what happens.
frozen bottles of water can be used to chill the water; this is high maintenance, but it does work.
good luck.