which is better?

Hi guys , what do people think is a better lighting set up,1 600 or 2 400's?

bifter said:

Hi guys , what do people think is a better lighting set up,1 600 or 2 400's?

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Better in what respect? It's a very open ended question and it depends entirely on what your own priorities are which you don't mention.

Lets look at some rough figures.

One 400w HPS will output about 55,000 lumens depending on bulb and use 3.8 amps on a 120v system. Two will output 110,000 lumens and use 7.6 amps total. That's 14,473 lumens per amp.

One 600 HPS will output about 90,000 lumens depending on bulb and use 5.7 amps on a 120v system. That's 15,789 lumens per amp.

So lumen per amp, the 600w will be cheaper to run. Due to the single point light source of the 600w HPS its light will also penetrate deeper into the plant canopy than the 2 400's will - 90,000 lumens v 55,000 lumens. You can only add lumens together for area coverage not depth penetration. A 400w will cover an area of about 4 x 4 ft reasonable well, and the 600w an area of about 6 x 6 foot.

So the answer depends entirely on the amount of square footage you need to cover, if it's much bigger than 6 x 6 then you need to be looking at more than one light setup, if it isn't the 600w will be your best bet. 2 x 600w HPS's would be better than 2 x 400w HPS's.

Thanks for the replies guys,the room will be 4ft square and about 6 ft high ,the only reason i asked was because i was originally going to buy a 600w light but i may have the chance of 2 400w lights and a propogator and six 400w bulbs for £50 which i thought was a steal
So it seems a 400w will be enough for my little room anyway and i could maybe flog the other or set up another room
cheers Bifter