how much is too much?

decided to get a hps for the flowering area, which is 28 x 28 x 48, i have a 4 inch 190 cfm inline fan vented outside, with an 80 cfm booster fan at the bottom of the box for fresh air. in that amount of space with that much air flow, would a 600 watt hps be too much? should i stick to 400? i'd really like to go 600 as long as im sure i wont fry my plants.

Roger A. Shrubber said:

decided to get a hps for the flowering area, which is 28 x 28 x 48, i have a 4 inch 190 cfm inline fan vented outside, with an 80 cfm booster fan at the bottom of the box for fresh air. in that amount of space with that much air flow, would a 600 watt hps be too much? should i stick to 400? i'd really like to go 600 as long as im sure i wont fry my plants.

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If you can keep temps in check.. go with the 600.. might as well ,better then having to buy it later.

thats the whole thing though, will i be able to keep it under 80 with a 600?
its 28x28x48, which = 21.7 cubic feet. the exhaust is 190 cfm, so it'll change the air in the area not quite 8 times per minute. i keep the house 72. i'd think that would be enough 72 degree air to keep things cooled down, with an 80 cfm fan blowing in at the bottom of the box, which isn't air tight to begin with.

If you get a dimmable ballast, you can run a 400w bulb on a 600w ballast, dialed down to 400 safetly, just dont accidently switch it up to 600w... i found this out when a 400w ballast died on me and i had an extra 600 at the time. Also you may find you can run the 600 in the winter but not in the summer without AC

The footprint of a 400 seems to fit your area,not sure you would end up with enough extra output to make the investment.The air cooled hoods i have seen use a 6 or 8in. flange and a 420 CFM fan or larger.A non cooled hood would be to hot and most cooled hoods need 3ft. across to hook up your flexible duct.

the square ceramic reflector option here http://www.ebay.com/itm/400w-400-watt-HPS-MH-Grow-Light-System-Set-Premium-Kit-Dimm-Green-House-/291003666817?var=&hash=item43c12b9181:m:mQhiL9RFEtNmiXJbv-6y-Zw is 20 X18, which im hoping is enough room.
i can buy a 6-2-4 adapter, and if it seems to be running hot i'll just get a 6 inch fan. i just had the 4 inch fan, but it was bought to help keep a damp area dry, never used it for cooling, think its 190 cfm. it helped keep a damp basement dry pretty well, had to empty the dehumidifier daily before, every 3 days after.

You need an ac.

Use a 600 hps cool tube and went it out not an open 600 watt should be no problem or maybe also consider getting a 6 inch 480 cfm I use 6-600 watt hps to flower and 3-400 watt MH TO VEGG

Sorry with a 6 inch inline fan carbon filter... To pull air out for each tent which are 4x4x 7 foot tall.

600w with cool tube is the best choice in my opinion

No AC yet.. I do have one just In case but so far it's been in the 70's in my tents

You have a 5.4 square feet footprint with only a 4 foot height.

600w would be 111.11w/square foot
400w would be 74w/square foot
250w would be 46w/square foot

It is generally recommended to aim for 50-80w per square foot of HPS lighting. So... I don't get why people are recommending a 600w?! He only has 4 foot of height. I can't imagine how hot it would get with only a 4inch fan, 111w/square foot of HPS and only 4ft of height! The question should be "250w or 400w?"!

600w will fry your plants.

Mine are 4x4 x 7 in hieght

This is what i ended up doing, still using a 300 watt led for veg
Went with a dimmable 400 watt hps, started it out at 75%, and the fan handled it easily, so i went to 100%, with the fan at 80%, and it stays at around 78.
I got a lux meter and it says i'm getting 50k at the tops of those plants. the led puts out 24k, plenty for veg, but not close to enough for flowering.
Had the exhaust going out the top back of the flowering box, which is actually 28 x 32 x 48. this was just a little too tight, so i plugged up the hole, and ran it through the top of the veg box. I taped around all the holes so they're light tight before i actually put plants in there.
i also used the booster fan i had to blow what little warm air there is into the flower box.

I have to keep things short and bushy, i have 37 inches to work with, so the SOG thing seems to be the way to go till i can afford to buy materials to build a taller box.
The veg room stays in the low 70s. I'm using a little humidifier in the veg room, keeps it around 50, a little of this is pulled into the flower room, so it stays around 35 in there, i'll update in a week or two and let you know how its going then

No disrespect but I think you should of just bought a 4x4x7' tent for flower and used that space for vegg ..

i live in a tiny house and have limited resources, if i had the room and the cash i'd have 2 4x4x7 tents and run 2 600 w mh in the veg and 2 600 watt hps in the flowering area, but reality being what it is, this is what i have to work with at the moment.
and i'm not looking to sell anything, i just am tired of buying it myself, how much room do i need to support one pothead? even if i just get .25 grams per watt thats still 1/4 lb. every 60 days, and i plan to stagger things once i get it going, so i should be harvesting a plant per month once things are rolling.
thats at least 2 ounces of good per month, if i can't stay high on a half ounce of good weed per week, maybe i need to dry out for a little while.

All of this could be solved by switching to an led COB setup. I changed from hps and I'm running consistently under 80*F now.

Chill. Your space is plenty Once you have it all dialed in I'm sure you'll be very happy with it You're already doing very well

Cool tube or lower wattage.

I'm running a 250-Watt HPS in a 24"x24" space and it's kicking ass. Don't be afraid to get a lower wattage light for your area, trust me without a cool tube it's going to get hot. My ladies have to suffer at 90 degrees until I can get an inline fan.

with the light at 400 watts i'm getting 50k lux at the tops of my plants, 35k and higher down under the canopy, if i drop it to 300 watts, it drops to 40k at the tops and 25 down under the canopy, and only runs 5 degrees cooler, i'd rather stay at 400 watts