those plants are not stunted or rootbound or malnourished at all,that system can hold 3 times as many plants as are in it now with ease,Ican never figure out why anyone would want a tall spindly plant,a tall plant decreases the light to surface ratio,takes longer to grow,and produces far less,as for pruning,i never prune an indoor plant,(unless i was only growing just one)those plants will eventually fill that space with a thick short canopy with plenty of well lit and exposed budsites,the thickness of the stems are an early indicator of that,this grow is a perfect and definitive example of hydroponic cultivation....bonbon