600 watt hps w/sealed hood. how many cfm does it take to stay cool.

I just bought a 600 watt hps lamp. Now I'm looking for a inline fan to cool the hood. How many cfm will i need? It is a very small setup with a big light. I want something quiet yet sufficient for cooling.

Yeesh, I remember my days of a 600watt in a space that was too small. Whats the square footage of your growspace?

*edit - Cubic footage of your growspace. Height x width x length

GrizzlyAdams said:

Yeesh, I remember my days of a 600watt in a space that was too small. Whats the square footage of your growspace?

*edit - Cubic footage of your growspace. Height x width x length

Click to expand...

8 h X 6 L X 2 W ....I should be pushing somewhere between 7000 and 1000 lumens of light per square ft. Ideally, I would have one mother, cut clones once every month or two. veg for two weeks and then finish flowering with the 600 watt hps. Thinking cfl for the mother and clones. Its going to be tight. Not sure of how many cfm s it will take to cool the light though.

I ran my 600 watt in a closet with the same cubic footage man. Was way too hot, ran a 75CFM cooltube the entire photoperiod and it wouldn't drop below 90F. Ran about 92 usually. You're thinking of running 600 watts for 12 square feet of growing area. Way overkill man, go smaller. If you want to use HID (I'm an HID person, I think you should) do a 400 watt if you're going HID. Light kicks ass, and a 250watt just isn't beefy enough now is it? - Most supply stores let you exchange setups for a nominal re-stocking fee and given 400W is cheaper you either won't pay anymore or have some extra money lying around.

If you're thinking of doing a mother and clones, you will need to wall off your growspace and put in two lighting systems and a semi-complex ventilation system. Depending on where the opening to your growspace is this could be easy or very difficult. If you only use one space, to flower the clones you're cutting from the mother, the mother will flower as well, boom you lose your mother. My advice would be to get some plants going and figure out how many plants you can grow well in that space and stick to it. Going too big is a really common mistake, don't overshoot, take things one step at a time.

Flowering takes far longer than the 3 weeks you're talking about with your clones. (1 for rooting, 2 for full veg) Unless you want to go through the hassle of dividing your growspace, I'd just run off seed crops or you're looking at building two rooms. One option you could utilize is build a propagation box that just grows clones. You can clone a clone 20x before the genetics start weakening and lets face it, thats a shitload of MJ. You could roll your closet 12/12 HPS and thats all it does with a modified dresser (or whatever ya like) next to it that has the clones you've taken off your first females. Lets say 8 clones. When they fill the box take 8 clones off your best prospects and move the plants to the HPS, root the clones, veg, re-clone, etc. Steady flowering in your closet. . . Its an idea anyway. Got some pics of this closet?

yo man... you can definitely run a 600w in there...

i had a 2.5' x 7' room that had 2x 1000w lights in it...

75 CFM is not enough... thats probably from a duct booster fan that is really running 25 CFM...

i'd get a 6" inline fan... they are about the same price as a 4" inline fan, but move more air... i'd shoot for 200CFM, and get a fan speed controller - that will let you turn it up to cool it down more if you must...

also - i use Quantum digital ballasts... which let you dim the HID light to 50% or 75% of its output... very nice for times when temps are out of control...

you could put 2 600s in that room if you wanted... but you'd need a separate air stream to exhaust the heat from the HIDs...

Thanks for the input guys. Well first off if i could clone the clones it would save me enough room for one or two more flowering plants. That would be good. Maybe I could just start from seed once a year. Good seeds get pretty expensive. I could put the propagation box above the flowering plants. there should be room for that. The balast is a 600 watt dimable MH/HPS Lumatek, which means I could always turn it down if needed. I can also switch lamps and veg with the MH. The hood is sealed with a 6 inch intake/output. So I will need at least a 200 CFM to keep things cool. This is my first grow so I know I'll have to tweak things as I go.

I don't have any pics yet. I'll try to post some as soon as I get setup and going. If I have to I'll start from seed each time, but clones would be the ideal way to eliminate the hassle of dealing with males. I'm open for opinions if u got em.

grow tents are the way. on ebay u can find 4x4x7 for like 130 with shipping. they have the ports an all for the ventillation of cooltubes or aircooled hoods. it will help alot im sure less construction an all plus temps shud get under control

With a 600 you will be spending way more money than you need to and putting too much money into a tiny space. A 400 watt will be cheaper to cool, cheaper to operate, and will allow you to keep the light closer to the plants offsetting some of the lost lumens. You could put a 5,000 watt bulb in a 2 foot space if you hooked a barn fan up to it, jesus. We're looking at what is practical.

As far as your bulbs go, they only really make conversion bulbs for metal halide in a 600watt and that doesn't mesh with lumatek or other digital ballasts very well. People are probably going to argue with this, but I know this shit for a fact. A metal halide conversion bulb is meant to run on HPS power. Since it is on a digital ballast that runs both MH and HPS power sources the bulb gets confused with the ballast and doesn't run consistent stable power. The conversion bulbs won't burn out right away, but the WILL burn out long before their expected hours. I'm having a hard time remembering the name of the company that just rolled out a complete line of digital bulbs, but they have a true 600 watt metal halide. If you're looking at making a long term investment, digital bulbs will last longer, lose lumens slower, and operate more efficiently. . . .sort of pricey though, the name is something pulse. Remember that digital ballasts are a new technology. Why do I know this? I'm a 600W HID user my friend. Lumatek as well.

Anyway, using a 400W light in that closet will
#1. Keep things cooler and reduce the need for ventilation thus enabling you to maintain higher levels of humidity (I'm assuming your intake isn't going to be above 65% RH). Can you do this while cooling a 600 watt with a monster fan? Hell yeah you could, but you'd need to have dual intake ports on your closet at least. One for a contained cooltube on your light and another for cycling fresh Co2 into your space. High humidity encourages thicker leaves that allow more energy storage. You might have way more light for your plants with a dry 600w, but a humid 400w they will be able to use more photosynthetic energy overnight AND during the day.
#2. Save you money. Smaller fans, chops 33% off your electricity bill, etc.
#3. Provide you with over 4,500 lumens per square foot with HPS light. MJ will be happy with 3-4k, its plenty. Believe me. Besides, if you REALLY want to break that 5-6k mark, buy some CFLs, mount them lower and your canopy management stops being an issue.
#4. Easier switching from MH/HPS. Bulbs are widely available for this wattage in both varieties as opposed to just HPS in 600w.
#5. If the fan stops working some friday morning and you don't check until saturday afternoon, the heat buildup from a 600watt in that closet will reach temps of well over 100F and cook your babies. Too big of a risk imho, equipment breakdown happens, I like to know if that happens the plants won't be as happy but they won't be extremely stressed or fucking dead.

I still think a 600watt is unnecessary overkill for this space. Doable, but not practical. I'd still recommend the exchange to a 400 watt but if you want to spend the extra money, time, etc its your call. Is anyone with me on this one?

i like that answer too. space is an issue. the bigger the space, the more light, only makes sense i think. ive seen some great 400 watt grows but its ur call and ur grow! im very prochoice, lol! i use two 600 watt cool tubes now in two ents 4x4x7. i was even thinkin of uppin another 250 per tent

yeah, plus with the tents i got ready made ducts for venting so it may be tighter in the closet unless u do some construction

Hi, Grizzly asked me to chime in with my 2cents.. so I thought I would check it out.
You are both right. I agree that the BEST suited light for your room is the 400 watter. 480 watts is optimum light. Venting fan for your space with that light would be minimum 88CFM.

If you push the 600watter, you are above optimum range and into the upper range limit. The max lighting for your room size shouldn't exceed 720watts of light and vent should be minimum 104CFM. In this upper range you should concider Co2 as well.

So by Grizzly telling you that it's a better option for you with 400.. he's dead on. But you CAN use the 600Watter, it's just overkill, and more $, more electricity..etc.

If you ? my #'s then PM me and I will show you how to get them.

Grizzly & Cowell - I'm not disputing what you say - a 400w would definitley work in there, so would a 600w... BUT - i have done some experimenting with HID lighting, and maximum brightness...

the Grow FAQs all say that the ideal light level on the floor is about 50watts of HID lighting per sq ft of floor space... bud up says his floor space is 6' x 2' - or 12 sq ft. if you wanted to hit 50w/sqft you would need EXACTLY 600 watts... but the only way to put 600w in an area that small is to vent the light heat separately.

I have an area that is roughly the same size... i use a screen that is 2ft x 7ft... in a room that is about 3 ft wide. i had 2KW in there, vented nicely, which was putting the overall room at 95watts/sq ft. (watts are easier to work with than lumens, and it works as long as you are comparing HID to HID)... but thats not entirely accurate... i had to 2kw focused right above the 2'x7' screen - so if you say that all of the light was on the screen only that would put it at 142watts/sq ft of screen.

this was NOT detrimental at all to my plants... they loved it actually - they will use every bit of light that they can get... they grow fast, and the buds are huge, and dense... the weight of the yield is directly proportional to the amount of light you have up to a certain point.... i put 2kw in there because there is no other light that would give me 2 lbs per harvest... if i would have gone with a single 600w, i would have only gotten 10-12 oz probably.

i know the 2KW was overkill... but i ran it like that for a few runs... then i "upgraded" to something more economical - 2 600w dimmable digital balasts - which removed about 8oz from my harvest, but costs much less to run... also i moved the 1KW lights into a 4x8' tent where i can get more bud/watt because of the amount of floor space...

here's some pix to show my 2KW setup over a 14sq ft screen...









the last pic was 1/2 way through harvest... i chopped the back 1/2 and remembered to take the pic... oh well.

so to the OP - rock on with your 600w - get a vented hood or a cool tube, and a 6" inline fan and vent the light directly... use a seperate air stream, and if that doesnt make enough bud, you could add another 600w in the air stream with the same inline fan to cool both...

good luck!

I'm with u man. I did overkill the light and with the 600, I'm going to have wasted light. I've just been hearing the

more light the better for so long that it kinda had me pump up to go big....lol. I read that the sun puts out 10,000 lums per

squ ft on a clear summer day. I used 12 as my sq footage and came up with 7500 lum per/ft with a 600 watter, but with

this small of an area i won't be able to concentrate all 90,000 lums where they need to be. I'll check on an exchange. If I

get stuck with the bigger light, are there any benefits other than tighter, bigger, faster growing plants hahaa. If i keep it I'll

need fresh cool intake air from the outdoor to off set the produced heat and a big exhaust. so (cowell) do u think a 100 cfm

inline fan would be sufficient to do this?

The plants look nice bloodshoot 420...what strain is it and how many plants per/squ foot? It looks like a hydro set up, but

kinda hard to tell by the pic.

Props on bloodshot's setup btw. Looks nice!

If you get the exchange and do the 400, I'd use the 100cfm with the dimmer switch to control fan speed as bloodshot said.

With the 600, I don't know if you'll need to pipe air in from the outside, just build a cooltube with a 200+ CFM fan and the dimmer on its own system. Piped intake to the hood, then exhaust back out. The goal of a circulation fan is to replace all the air in your growspace in 5 minutes. so roughly 100 cubic foot space, you need a 20cfm fan. Bigger doesn't hurt though, a 50 would do you fine for circulation.

Now that I'm thinking about it, this thread has a shit ton of information for you and I seriously doubt anything further is needed. You got whatcha need for both the 600 and the 400 setup. If you do get stuck with the bigger light? Why do you think I know how overly hot your closet is going to get with a 600 . It happens man, go big or go home right?

Anyway, +rep to cowell for helpin out with the 3rd party opinion and +rep to bloodshot. Not enough people will contradict a valid opinion with another valid opinion. Gotta admit when you came back with that stuff this morning I considered you sort of a crackpot but you backed it up. I'm sure that 2k setup increased your yields but JESUS CHRIST! Idk if i've ever heard of that much light crammed into that small of a space. Props ya crazy bastard !

I'm out, bud up - best of luck dude.

thanks for the advice...very solid. I may start a new post when i get things going. thanks everyone

htgsupply.com has a great 6 inch inline for ur aircooled system, i need two myself for my cool tubes 600 each. i thought i wud need a vortex but my hydro shop was like thats overkill. im savin like 300 bucks goin with the lower power one

kushykushkushy said:

grow tents are the way. on ebay u can find 4x4x7 for like 130 with shipping. they have the ports an all for the ventillation of cooltubes or aircooled hoods. it will help alot im sure less construction an all plus temps shud get under control

Click to expand...

amazon. -100