# How many 400w hps ( lumens vs heat choice)



## saycheese (Feb 23, 2013)

Hi all I have a lighting Q for you,

I have 1x1x2 space with 4" in and 6" out

I was running 400w hps + 125w cfl at a 17" distance getting temp of 29c 

Im now running 2x 400w hps at 20" distance getting 34c

Lumen chart says I'm getting 50% lumen increase for 6 degrees heat
I could raise them further so it's more like 20% lumen increase for say 3 degrees (32-33c)

I don't care about the extra electric as long as I yield say 20grams more it'll be fine so any more than that would be bonus

- would you go with lower lumens lower temp with one light source or would you take two lights and suffer extra 3-4 degrees for better spread and few more lumens?

If I run this run at 32c with (roughly I think) 11000 lumens will I be better off than running at 29c with 8-9000 lumens I don't mind if slightly less dense but I don't want to risk a large drop in quality for only a small gain in quantity


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## pcduck (Feb 23, 2013)

Those are some high temps, either way.

What type of fan are you using for exhaust?

What is your ambient temp?

Where is your exhaust intake pulling its air from?


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## The Hemp Goddess (Feb 23, 2013)

When you say 1 x 1 x 2, are you talking meters?

Tell us about your fans and ventilation system.  Are you running air cooled hoods?  You would probably be far better off with a passive intake and more exhaust--you do need to deal with that heat.  Also 20" away is quite a ways for a 400W--you are losing a lot of lumens that far away.  I can run a 1000W about 8-12" away with no problems.


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## saycheese (Feb 23, 2013)

Hi people, lights on in 15mins-
 I reckon I'll probably have to switch one of the lamps off after half hour, I suppose if the temps go up slower it means the problem is less severe. it flew up to 40c with both lamps @ 10" (which is where I'd love them to be but that's not gona happen)

Air comes from outside

Exhaust Fan -I can't even remember the model number it was either system air or rvk so I don't know the precise cfm's but it's probably the lower cfm model of 6" I boxed it in with crack foam years ago, have successfully vented two spaces the same as my current with a 400w In each with same fan and tee-piece before and it was just about adequate

12" Oscillating fan but not Osc, pointing just above canopy

Standard reflectors no cooltubes

size is in metres 

Temps at pot level 25c and at 2" above canopy in direct light 34c ( plants 1.5" tall)

I checked the lumens charts and I wasnt getting vast amount of lumens per watt already with one bulb, but with two there is at least a 10% lumen increase to be had with only minimal temp increase, but I suppose more spread less penetration?


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## saycheese (Feb 23, 2013)

Definately wasn't working ( up to 40c ) , maybe with more extraction but in this case no,
Will be returning to 125cfl + 430w hps ASAP 

Two 400s will have to wait till I have bigger space/ extraction


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## The Hemp Goddess (Feb 23, 2013)

The CFL that far away is doing nothing but wasting electricity.  I would recommend getting your ventilation in order so that you can run both HPS.


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## ShOrTbUs (Feb 23, 2013)

hxxp://www.amazon.com/Inch-ValuLine-Centrifugal-Inline-Fan/dp/B0033BONPQ/ref=sr_1_1?ie=UTF8&qid=1361680301&sr=8-1&keywords=cap+valueline+6%22+inline+fan

if you invest 85$ this fan has 435 cfm and will be able to cool both your 400watt hps. your room should run at 24c-28c while the lights are on.


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