lighting info needed

[boon]

i growing in a room 8foot long x 4 foot wide x 7 foot high and have been using 2 x 600w hps lights but its been getting too hot in there during the warmer months even with extractor on full

i was wondering if it was better if i got 2 x 400w hps lights or 1 x 1000w hps light to replace.

can you tell me if one is better than the other please or if there is another solution

[stinkyattic]

Your lights are correct for your space, and you have another choice, which is to replace the HOODS with ones that may be air-cooled. They are GREAT!
Also, if your ballasts are in the same room as your plants, put them somewhere else- a ballast makes a LOT of heat.
I would not recommend replacing the light you have with either of the configurations you suggested. You will still have heat problems with either; a 600 is not much hotter than a 400. Air cooling the lamp is the most efficient option.

[boon]

would the yield change using a 400w set up?.

[stinkyattic]

All other things being equal, yes. Your yield will be 2/3 of the yield with a pair of 600s.
However, if you can't control temperatures any other way, your yield could potentially be higher with a system that produces less heat. But a pair of 400s is not going to solve a heat problem if a pair of 600s gives you one in that space. AIR COOL, ftw!

You DO run your lights during the coolest part of the day, right?

[boon]

yeah.

19:00 till 07:00