Glad to see you here on RIU.
You have come to the right place to learn how to grow MARIJUANA IN AN INDOOR ENVOIRMENT, which means all you know about growing almond trees outdoors means dick. As far as some salesman recommending anything, usually they want to sell the item they recommend, and usually they cant grow a tomato (that's why they are salesmen)
The guy called Dr. Who, (check out his profile) who has actually been growing herb probably longer than you have been alive, who said that you probably don't know shit about growing pot is right, otherwise you wouldn't be here asking for knowledge.
I don't really mean to sound mean, but I haven't been laid yet today. Anyway Free range humanoid, (you should start a new profile, and change that dumb fucking name) one thing you should have learned by now seeing that you are experienced with growing (trees really don't count though seeing as they are trees, while marijuana is a PLANT) you should know that you don't plant 28 trees at once unless you know what the fuck you are doing. You start with a couple and once you figure out if the soil is good, and the lighting is good and you can handle the insect and diseases that might occur (probably will sooner or later) and getting the nutrient requirements figured out, THEN YOU PLANT MORE. You want to start your 1st run in hydro ( much less forgiven than soil), indoors, and you think you can grow 28 plants? YOU ARE FUNNY.
Really my friend, start MUCH smaller, like at the most 3 or 4 plants ( so you want to grow commercial? Hint #1 is you better have buyers lined up now, and not some assholes you met in a bar that can sell a pound a week) until you get it figured out. Check out Amazon for some good tables at a good price. It takes 3 MONTHS to grow a plant, at the very least, so you really don't want to waste the lot's of money it costs to set up a system ( lights, food, seeds, meters, and additives like Calmag ( I'll blow you if you know what that is, and it is very important in hydro grows to give you a hint) Anyway, my lover just walked in, so it's time to relieve some tension ( he really knows how to give a foot rub). Good luck, and expect some abuse (only the real assholes will do that, and they are everywhere anyway) but most are nice people here. Good luck growing, and PM me if you need some help. TC