Old school tank guy help needed

Seem to have gotten lost in all the info on this site... need some help to get me back on track.. "short version" was bored at work so made a 50 out of a broken 100 set it up threw in a undergravel some salt water ,some old coral and some T8 daylights*4 . So start looking around the web everybody is doing sumps.. Ok.. grab a old 50 stick it under build a 1 1/4 over flow throw in 5 gal bio balls and a big fountain pump back up , so read some more nobody use bio balls anymore? undergravels are bad? now i need a reefarium? live rock ,live sand,a skimmer, a rd/so something.. im lost have 3 50g tanks all setup kinda plumbed toghether . have like 3 more tanks sitting around doin nothing,stacks of glass and lots of silicone and pvc and a wall rack that could hold 10 tanks.. Any body help me i seem to be lost in what direction to go (still have a 15 year old fish only sw 100 gal at home running undergravel and 2 powerheads and some very old damsels and clowns.)

 

I would say undergravel is fine for fish only but for reef set up's it's
All> throw the bio balls away
sand bed, skimmer, refugeium, and proper lighting for what ya want to grow.