What size light should I buy?

[SkeletorsUncl]

I hope this topic hasn't been covered before. I searched and was unable to find an answer to my problem. I am contemplating a grow tent that is 4' X 4' x 7'. I only want to grow one plant at a time, because I don't smoke much, have NO intention of selling anything, and don't want to build up a massive stash.

My question is thus: what size light should I get? I was gifted a 400 watt HPS/MH switchable ballast, but the last time I plugged it in it sparked, started buzzing loudly, and shocked me pretty bad when I touched the case of the ballast. This is when it is in the OFF position (as opposed to the MH or HPS position). It also has trouble starting the HPS bulb (sometimes it will start, sometimes not). So I don't think it's safe.

So I have to buy a light, I'm trying to decide whether I would benefit from buying something larger than a 400 watt, considering I will only have one plant at any given time. I've read a lot about lighting, and the consensus seems to be that a 600 watt is perfect for a 4' x 4' room, but everyone talks about how many plants you can cover with that wattage and area. I have no desire to achieve a maximum yield for my space. I simply want to achieve a maximum yield from one plant at a time, while wasting as little electricity as possible.

What I've been looking at thus far is a dimmable ballast (either 1000 watt or 600 watt), or a regular 600 watt, or possibly the new 860 watt Philips ceramic metal halide. Or if it would work, even the 330 watt ceramic. I've read good things about the ceramics, but I don't know enough about lighting to make a decision. Thanks to everyone for any assistance possible!

TLDR: What wattage and type of light should I buy to maximize yield from ONE plant (and only one plant at a time) in a 4' x 4' x 7' tent while minimizing electrical costs. Thanks!

 

[JJ Bones]

Then get a 3x3 with the 400w setup.

 

[Icemud]

a 4x4 tent is a very large tent for 1 plant... you probably could reduce the tent size to a 3x3 tent like mentioned above. If you stick with the 4x4 tent, I would go with a 600w HID or LED equivalant, and if you go with a 3x3 tent I still would recommend a 600w, but 400w would be more appropriate. Ceramic Metal Halide bulbs are by far one of the best spectrums for growing so if you go 400w, definitely CMH bulb would be your best option.

 

[SkeletorsUncl]

I already have the tent, so getting a 3 x 3 isn't really an option. Icemud, would you think this bulb coupled with a ballast like this would work well? I would imagine I could use the hood I already have, which is this Yield Master II.

 

[Icemud]

I already have the tent, so getting a 3 x 3 isn't really an option. Icemud, would you think this bulb coupled with a ballast like this would work well? I would imagine I could use the hood I already have, which is this Yield Master II.

That ballast is fine, I have 2 of them and they work well. That CMH bulb is the newer Phillips bulb and by looking at the spectral chart it looks as it will be fine. Also it seems that it will work on both magnetic and electronic pulse start ballasts so it should be ok to use with that ballast. I would suggest if you can find them (there discontinued) to look for the Phillips CMH bulb with the part number CDM4000S50/HOR/4K/ALTO, they are the older style, but IMO even a better spectrum than the new ones. Both are very good in comparison to HPS or MH. As far as reflectors, I don't know too much about them as I just used what I got with my lights (2nd hand). I'm sure any reflector will work, just make sure it will cover your grow area.

 

[SkeletorsUncl]

So Icemud, would you recommend the aforementioned 400 watt CMH, or maybe a Mars II 400 or 700? Your LED grow looks like it went pretty well.