Picking up where son left off

Welcome to 3reef RoGames. Well, your son has certainly thrown you to the Lions, so to speak. ;D J/K From the sounds of your post, I can assume you must have a small grasp of the SW concept. Which is better than most ppl who start into this hobby, myself included( 20+ yrs ago ). This hobby can be at times very frustrating, so get out your patience hat and have it handy. While your in the closet, also get the common sense hat too. Pharmrjohn gave you some great advice. Your son must have some testing equipment, if not, you will need the following.
You'll need Nh3, No2, No3, Cal, Dkh/Alk, Ph, Mag and Po4. Although your set up is 3 yrs old, you probably wont need the Nh3 and No2, but its good to have. You have joined a great site, everyone is always willing to help and friendly. Some pics of your set up would be great at this time. Hope to see you around and good luck with your new journey. Luna