1st grow....need help

Hello, I just started growing and have 2 plants that are about 2 and 1/2 months old. Ive just been watering them and putting a few drops of Superthrive in with it. They were doing ok but ever since i went from fluorescent to hps (400watt) lights they have been going the other way. Temps do get a bit high in the grow area 93 highest, So i started leaving the door open. Still they seem lacking something . Both are close to 33 inches tall, but one has stopped veging almost. Lots of yellowing lower leaves. What I need to know is whats the best Nuts i can use and for what stages. And do i need to test the water or add anything to it...maybe dont add superthrive? Im lost. This is my first grow so any and all help is appreciated. And when should a adjust the time and make them flower (normally) when they are healthy. Do they have to be a certain size or age?Im thinking of going back to just fluorescent T5 lights becoz they were doing much better then. The room is a closet about 5 x 3 ft. thanks all. Ill try to add pics soon.

easiest IMO would be get a good 2 or 3 part. i use general hydro, but have heard good things about Dyna-grow too (dyna grow is technically a 1 part, but have seen people needing to add something to the mix due to lack of N). Both are easy. Just go to the manufactures website and they will have a feeding schedule there. Important to rememebr to start out SLOW. Dont over due it. You will probably NEVER be giving you plants exactly what is on the feeding schedule. Start at .25 strength and go from there. i would get your plants healthy before going into flower. How long have you been on 12/12?

Just trim them down a bit. This will give you a couple weeks to get them recovered, but you need nutes asap.

post some pics though and we will see what else we can help you with.

93 degrees is much too warm. How long was it that high and what are your current ambient temps? How far from your plant(s) do you have the 400w? As for nutes, what medium are you using? We need this information to gauge what nutes it may contain already. What are your humidity and PH levels? There are many simple and 'newbie proof' systems available for nutrients. But the needs are different for each medium. Sorry to answer your thread with more questions, but we cannot help you unless you give more specifics.

As a suggestion when starting a first grow it is prudent to read, study, pln and act. Please click the link in my signature. You will find several grow videos from master growers for first timers. Best of luck to you and don't be afraid to ask more questions. No one here wants to see your babies dead. Welcome to RIU!

Yeah the temp is now down to high 83/low 66 with the door open . Humidity is high 68/low39 %.The plants are about 2 1/2 to 3 feet below the HPS lights. I dont know what Medium is,sorry. I potted them in Miracle grow organic potting mix..Theres nothing that states what mixture is in it. just says it feeds up to 2 months. I been putting 2 drops of superthrive per gallon of filtered water(2 gallon container)...and a little bit of hydrogen peroxide . thats it. I dont know what to add to it as im new at this and only know a little about growing. I read somewhere that foxfarm is good? I got some pics below. Lots of down curling going on. And yellowing. Im hoping I can save them.
Thanks for the help its much needed..lol

Also ive never topped them yet, not sure when to do that either.lol..amateur i am.

just a suggestion...mb prune now. they still have to stretch yet.