Home | Community | Message Board


RVF Garden Supply
Please support our sponsors.

Cannabis, Marijuana, Ganja & Greens >> Cannabis Cultivation

Welcome to the Growery Message Board! You are experiencing a small sample of what the site has to offer. Please login or register to post messages and view our exclusive members-only content. You'll gain access to additional forums, file attachments, board customizations, encrypted private messages, and much more!

Amazon Shop for: HPS

Jump to first unread post. Pages: 1
OfflineIcon
Stranger
 User Gallery
Registered: 06/09/15
Posts: 16
Last seen: 1 year, 2 months
Fan options for 50 cubic foot, 600w HPS tent
    #781776 - 06/12/15 05:07 AM (1 year, 5 months ago)

I'm designing the ventilation for my 36"x36"x72" tent, about 50 cubic feet. I'll be using a 600w HID in a 6" vented reflector. The tent has four 6" ports at the top so I have a couple design options. The most popular setup I've seen people using is hanging their carbon filter on the ceiling, connected to an inline fan, connected to the vented hood - exhausting the air through the scrubber and cooling the lamp all through one duct.

While researching, I came across another design, "Two Stage Ventilation"

Quote:



LIGHTING CFM = 3.16*(Total Watts)/deltaT
where deltaT = 20 to 30 *F

VENTILATION = 1 - 5 MpAC (Minutes per Air Change) or 0.2 to 1 Air Change Per Minute (ACpM)

Intake Area = 2 x Exhaust Area for EACH section

Fans - Axial for Lighting maximum airflow, minimal pressure loss
Small blower, inline or axial for scrubber

Example: A 400 W HPS in a 3 x 3 x 4 cabinet with a ventilated hood needs 63 - 42 CFM of cooling for a 20-30*F temp rise in the exhaust temps with a 1-2 *F rise in the growbox. 5 Minutes between Air Changes requires only 7 CFM through the scrubber.

Pros:
unrestricted airflow through lighting allows fan to operate at maximum rated flow
low air flow rates allow for smallest scrubber
use of less expensive fans as design is more efficient
Lighting exhaust deltaT can be 20-30*F while maintaining low grow chamber temps
Much quieter as axial fans operate at 20-30 db compared to 60-70 for centrifugal fans

Cons:
more equipment
more intake and exhausts require more light proofing
ventilation design is more complex
https://www.icmag.com/ic/showthread.php?t=112862




I found this equation for cooling the lights:
CFM = 3 x Watts / Tdiff (in Fahrenheit)
Tdiff = target room temp - intake air temp (82f - 68f = 14 in my case)
So to cool my 600w light I need... 3 x 600 / 14 = 124 CFM

Ventilation specs would be 50 cubic feet changed every 2 minutes, or 100cfm.
I read that if you're air-cooling your light separate, you still add 5% cfm to account for the leftover temperature increase. You also add 20% to account for the carbon filter. I also added a miscellaneous 5% for unknown reasons.
100 cfm + (100 x .05) + (100 x .2) + (100 x .05) = 130 cfm
http://botanical.com/hydro/air/calculating_fan_requirements.html

Does my math look right for those two different CFM requirements? If so, a 150 cfm axial fan for the light and 150 cfm inline for the scrubber should cover my needs.

Noise is also a concern; but most inline fans seem to make similar amounts of noise whether they are 150 cfm, 300 cfm, or a 300 dimmed to 150, etc.  So it doesn't seem like the Two-Stage design would be any quieter than otherwise.

I guess my question is whether getting two 150 cfm fans and setting them up this way would truly be better than just getting one more powerful fan that's hooked up in one system? Considering differences in noise, air changes per minute, and budget concerns. Thank youuu guys!


Post Extras: Print Post  Remind Me! Notify Moderator
OfflineIcon
Stranger
 User Gallery
Registered: 06/09/15
Posts: 16
Last seen: 1 year, 2 months
Re: Fan options for 50 cubic foot, 600w HPS tent [Re: Icon]
    #781777 - 06/12/15 05:18 AM (1 year, 5 months ago)

I'm having trouble even finding a 6" inline fan with such little CFM. Most have around 300 cfm, which if I have to go with one of those it would seem to defeat the purpose of splitting the ventilation up if one fan can handle the whole job. Thanks for your experience and opinions!


Post Extras: Print Post  Remind Me! Notify Moderator
InvisibleCrushNazT
Male


Registered: 07/23/13
Posts: 927
Loc: Colorado Flag
Re: Fan options for 50 cubic foot, 600w HPS tent [Re: Icon]
    #781778 - 06/12/15 09:12 AM (1 year, 5 months ago)

first, you want to push the air over the lights, not pull it through, that heat from the light can fuck the fan up and burn it out.

i suggest having one intake, and one exhaust. pull air through a carbon filter, push it through your light, and out the tent. you dont need 2 separate inline fans for your tent.


Post Extras: Print Post  Remind Me! Notify Moderator
OfflineIcon
Stranger
 User Gallery
Registered: 06/09/15
Posts: 16
Last seen: 1 year, 2 months
Re: Fan options for 50 cubic foot, 600w HPS tent [Re: CrushNazT]
    #781799 - 06/12/15 04:28 PM (1 year, 5 months ago)

Quote:

CrushNazT said:
first, you want to push the air over the lights, not pull it through, that heat from the light can fuck the fan up and burn it out.

i suggest having one intake, and one exhaust. pull air through a carbon filter, push it through your light, and out the tent. you dont need 2 separate inline fans for your tent.




I wasn't talking about any intake fans actually. Considering 2 exhaust fans, intake would be passive. Thanks for your input though. I am starting to lean more toward the filter > fan > light > exhaust route mostly for space concerns. I think it would get pretty tight running two lines of ducting around the reflector in a 3x3. At the same time, a properly cooled lamp would allow me to use more of the limited space between the plants and glass... still undecided.

The main con though of the one-stage setup seems to be needing much more air changes per minute than the plants prefer just to cool the light. Anyone know how big of a stress it is for the plants to feel 5 ACPM instead of 1-3?

Quote:



Pros:
single fan design means less equipment to purchase
Cooltube/Ventilated Hood improves cooling significantly by trapping most of the heat in the hood
Less airflow through the grow chamber compared to the above designs but still high.

Cons:
Fan operates at 50% or less airflow due to large pressure drop across scrubber
High SP requires a Centrifugal Blower, won't work with Axial fans
Fan/Filter Curves are needed to determine working airflow
Scrubber is many times larger than Ventilation specs to get light cooling airflow
many restrictions in multi chamber designs require special attention to intakes and intrachamber airflow
high airflow for to cool lights creates stress on plants where only 0.2 ACpM is needed
high airflow through scrubber reduces effectiveness
Centrifugal Blower and Inline Fans are very noisy 60-70 db




Edited by Icon (06/12/15 05:02 PM)


Post Extras: Print Post  Remind Me! Notify Moderator
OfflineBig Bear
Earf Child


Registered: 02/16/15
Posts: 249
Loc: In Love, On Time Flag
Last seen: 1 month, 13 days
Re: Fan options for 50 cubic foot, 600w HPS tent [Re: Icon]
    #781801 - 06/12/15 05:02 PM (1 year, 5 months ago)

Don't over think it just pull the air through a carbon filter.  You might not even need to duct a light if it's just one like that but it certainly won't hurt.  I didn't read your whole post tbh but I think if you have passive intake on the exhaust fan and then push the air through your lights as mentioned, you'll be fine


--------------------
:gd_icon:Still Alive:gd_icon:


Post Extras: Print Post  Remind Me! Notify Moderator
OfflineIcon
Stranger
 User Gallery
Registered: 06/09/15
Posts: 16
Last seen: 1 year, 2 months
Re: Fan options for 50 cubic foot, 600w HPS tent [Re: Big Bear]
    #781814 - 06/12/15 05:48 PM (1 year, 5 months ago)

Wish you guys would read the whole thing :tongue: Sorry it's so long. I already know that your suggested option is possible and also the most popular design. Of course the air will be pulled through a carbon filter and blown over the light no matter which design I choose. The whole point of this thread was to compare that traditional One-Stage method with a Two-Stage ventilation system. I see much fewer people using that setup but the thread and quotes I linked seem to say it's more efficient and less stressful on the plants and fans. Does anyone have experience or the patience to review the Two-Stage system and tell me what they think?


Edited by Icon (06/12/15 05:52 PM)


Post Extras: Print Post  Remind Me! Notify Moderator
InvisibleCrushNazT
Male


Registered: 07/23/13
Posts: 927
Loc: Colorado Flag
Re: Fan options for 50 cubic foot, 600w HPS tent [Re: Icon]
    #781815 - 06/12/15 06:56 PM (1 year, 5 months ago)

with no air intake, your "passive" exhaust will be so much that the sides of your tent will suck in the entire time your fan is on.


Post Extras: Print Post  Remind Me! Notify Moderator
OfflineIcon
Stranger
 User Gallery
Registered: 06/09/15
Posts: 16
Last seen: 1 year, 2 months
Re: Fan options for 50 cubic foot, 600w HPS tent [Re: CrushNazT]
    #781821 - 06/12/15 08:05 PM (1 year, 5 months ago)

Quote:

CrushNazT said:
with no air intake, your "passive" exhaust will be so much that the sides of your tent will suck in the entire time your fan is on.




huh? I've never heard of passive exhaust... no one here is talking about that.

I'm planning to have an inline fan for the exhaust... it will hang at the top with the carbon filter. The tent has duct holes at the bottom that I will use for passive intake from the room the tent is in. I definitely won't need an intake fan; that was never a question.


Edited by Icon (06/12/15 08:06 PM)


Post Extras: Print Post  Remind Me! Notify Moderator
InvisibleCrushNazT
Male


Registered: 07/23/13
Posts: 927
Loc: Colorado Flag
Re: Fan options for 50 cubic foot, 600w HPS tent [Re: Icon]
    #781826 - 06/12/15 08:11 PM (1 year, 5 months ago)

excuse me, i meant passive INTAKE. i use a tent too. this is my setup



and i have a 6" duct booster as an air intake, and the inline fan inside the tent still sucks in the walls of the tent.

just lettin ya know thatll happen.


Post Extras: Print Post  Remind Me! Notify Moderator
OfflineIcon
Stranger
 User Gallery
Registered: 06/09/15
Posts: 16
Last seen: 1 year, 2 months
Re: Fan options for 50 cubic foot, 600w HPS tent [Re: CrushNazT]
    #781829 - 06/12/15 08:31 PM (1 year, 5 months ago)

Ohh okay, hmmm. I guess that won't be too big of an issue. I think that would be another advantage of the Two-Stage venting system because you could use lower cfm fans and get fewer air changes per minute. Some of the designs I see people suggesting must be changing the air 5-10 times per minute and I can see that creating a huge vacuum in the tent. I'm aiming for around 2 air changes per minute which I doubt will suck on the tent walls and should disturb the plants less too.


Post Extras: Print Post  Remind Me! Notify Moderator
OfflineBig Bear
Earf Child


Registered: 02/16/15
Posts: 249
Loc: In Love, On Time Flag
Last seen: 1 month, 13 days
Re: Fan options for 50 cubic foot, 600w HPS tent [Re: Icon]
    #781843 - 06/13/15 12:25 AM (1 year, 5 months ago)

If your concern with the way I suggested is the plants being stressed then you should know that I have tons of air moving through my tent and my plants love it.  So long as you arent blowing them directly and wind damaging them they will be fine.  I don't see why your way wouldn't work.  For my needs I needed more airflow as my tent is 4x8 with two 1000w HPS bulbs.


--------------------
:gd_icon:Still Alive:gd_icon:


Post Extras: Print Post  Remind Me! Notify Moderator
OfflineIcon
Stranger
 User Gallery
Registered: 06/09/15
Posts: 16
Last seen: 1 year, 2 months
Re: Fan options for 50 cubic foot, 600w HPS tent [Re: Big Bear]
    #781850 - 06/13/15 01:18 AM (1 year, 5 months ago)

Yea I decided I might be worrying too much about wind stressing them, making it all too complicated. Was reading threads literally all day and I think I've narrowed down my choice. For a 3x3 foot print, seems the best reflector is the blockbuster or super sun 2. Both are air cooled with a 6" flange. For ventilation I decided my space is pretty small and the One-Stage system will be fine to cool the lamp while scrubbing the air. The target for cooling the 600w light and exhausting the room twice per minute is 150 cfm. I decided a 4" fan / filter would be perfect for my space, 6" seems overkill now. Going to go with the 4" Hurricane inline fan @ 171 CFM and the 4" x 12" Phresh filter @ 200 cfm. Going to hang the filter, connected to the fan which will suck into the 4" duckting, then a 4" to 6" reducer connected to the reflector, pushing air over the bulb and out of the tent.

At this point one of the only things I'm wondering is whether to reduce the ducting back down to 4" after the reflector, or just use 6" for exiting the tent. I'm guessing it doesn't matter much, but would there be any added air resistance from reducing the ducting back down to 4" from the reflector cab? Would be cheaper if I can just stick with 4" ducting, but I don't want to sacrifice performance.


Post Extras: Print Post  Remind Me! Notify Moderator
InvisibleCrushNazT
Male


Registered: 07/23/13
Posts: 927
Loc: Colorado Flag
Re: Fan options for 50 cubic foot, 600w HPS tent [Re: Icon]
    #781859 - 06/13/15 08:21 AM (1 year, 5 months ago)

Quote:

Icon said:
Yea I decided I might be worrying too much about wind stressing them, making it all too complicated. Was reading threads literally all day and I think I've narrowed down my choice. For a 3x3 foot print, seems the best reflector is the blockbuster or super sun 2. Both are air cooled with a 6" flange. For ventilation I decided my space is pretty small and the One-Stage system will be fine to cool the lamp while scrubbing the air. The target for cooling the 600w light and exhausting the room twice per minute is 150 cfm. I decided a 4" fan / filter would be perfect for my space, 6" seems overkill now. Going to go with the 4" Hurricane inline fan @ 171 CFM and the 4" x 12" Phresh filter @ 200 cfm. Going to hang the filter, connected to the fan which will suck into the 4" duckting, then a 4" to 6" reducer connected to the reflector, pushing air over the bulb and out of the tent.

At this point one of the only things I'm wondering is whether to reduce the ducting back down to 4" after the reflector, or just use 6" for exiting the tent. I'm guessing it doesn't matter much, but would there be any added air resistance from reducing the ducting back down to 4" from the reflector cab? Would be cheaper if I can just stick with 4" ducting, but I don't want to sacrifice performance.




with a tent that small, id go with the super sun. its a smaller and lighter reflector compared to the blockbuster. i started with a super sun then went to a 6" blockbuster. only good thing about the blockbuster here is a square light footprint.

i would use a 6" inline to cool your light and a 4" inline connected to a 4"x12" phresh filter. im not sure a 4" fan will move enough cfm to cool a 600w


Post Extras: Print Post  Remind Me! Notify Moderator
OfflineIcon
Stranger
 User Gallery
Registered: 06/09/15
Posts: 16
Last seen: 1 year, 2 months
Re: Fan options for 50 cubic foot, 600w HPS tent [Re: CrushNazT]
    #782198 - 06/17/15 02:28 AM (1 year, 5 months ago)

Incase anyone else sees this and is wondering what might be best for a 3x3x6' tent, I finally decided to actually go with an LED light. I've read 400w HID is enough for 3x3, while 600w will give you a greater yield. This is the only space I will have to grow so I wanted to maximize it. But I decided 600w in a tent that size would be very difficult. The tent is only 6 feet high and I figured I would need to hang the light at least 2 feet above the plants. With a reflector, the minimum dimensions for a 600w would have taken the entire top half of my tent.

I was also having a very hard time trying to map out a fan and filter that I could cool the light and room with. I figured I would need at least the 4x12" filter, and the smallest 4" inline fan is 8" long, making the shortest possible exhaust 20 inches long and 8 inches wide. I looked at pretty much every reflector on the market and even the smallest good ones are still 20-24 inches wide/long. If I wanted to hang a 20" wide reflector in the center of my tent, that only leaves 8" on a side for the exhaust. So I could fit the exhaust exactly, but I think it'd work better with a couple inches of breathing room. Then by having the filter/fan and reflector side by side, I'd have to make a U-bend in the ducting to connect them. A 22" long reflector hung in the center of a 36" tent only gives 7" on each end to work with. I'd need a 4" to 6" duct enlarger because all reflectors have 6" flanges. The enlargers are 6" long themselves, so using them directly on the reflector would use all my space. Connected to the exhaust however, would bring that to a total 26" length. Then I'd still have to make that U-bend with 6" ducting while the reflector only has 7" of space... so idk if that's even possible but it'd be at best a 90 degree turn which I hear is terrible for air flow.

So I finally accepted the idea that a 600w HID fixture in a 3x3x6 foot tent is just impractical if you also want it hung center and air cooled with a carbon filter. I probably would have gone with it if I had a 4x4 space or if I didn't need to stealthily have the filter and fan crammed inside the tent.

I think while searching for "Best light for a 3x3 tent" I came across Mars Hydro LED's. I was aware of LED's already, but thought the only good ones were way out of my price range. (Advanced LED brand lights go for $2,200 per 600w fixture!) There's a lot of good reviews and information out there saying that Mars Hyrdo II series LED's are good enough to compete with HID and other LED systems. They're actually affordable but still better built than cheap, knock off LED lights. From my research, I'd say they are the best value of the high-end LED lighting. I'm totally new to lighting, but they seem to be very active in the online community and have listened to customer requests and updated their products several times over the past couple years. While they may not have been a good option originally, the current product seems to have fixed most of the only complaints I could find. My only hesitation is that LED's don't have the penetration power of HID. Apparently LED's started with less than 1 watt per diode, but have been increasing to 3, 5, 10 and even more watts each to give a stronger beam that can penetrate further.

I decided to go with a MARS Hydro II 1200w. It's an array of 240 x 5w diodes. It'll definitely be enough light for a 3x3 footprint and I hope it'll be enough strength to flower a couple feet worth of foliage. Its true wattage draw is about 550, which is a potential comparison to the flowering power of 600w HPS. (60 watts per sq. ft.) The best part is that the LED's run cool and the fixture has fans that keep it around 88 degrees F. It's also a square 18", which I'll be able to hang perfectly center with 9" on every side. This will basically eliminate my tricky problem of running the ducting; I have a lot more options now and am not worried anymore about overheating the small tent at all. I'll still be using the 4x12 phresh filter with 4" inline fan, though now I'll dial it down with a speed controller to about 1 air change per minute.

Thanks again to the people who helped me work out a solution. I'll update here again or in another thread once I have actual experience with the light in this space.


Edited by Icon (06/17/15 04:27 AM)


Post Extras: Print Post  Remind Me! Notify Moderator
OfflineIcon
Stranger
 User Gallery
Registered: 06/09/15
Posts: 16
Last seen: 1 year, 2 months
Re: Fan options for 50 cubic foot, 600w HPS tent [Re: Icon]
    #789533 - 08/14/15 01:04 AM (1 year, 3 months ago)



Here's what the setup that I went with looks like. 3x3 tent, 170cfm fan, 150cfm scrubber, the Mars 1200w. I'm extremely happy with the setup and I think I'm maxing out the space as best I can. There's just no way I could have fit a HPS reflector in the top of the tent. The LED is 4 inches thick and has its own fans that keep it cool, the tent stays around 78f during lights on.

Here's how the ladies look today! 1 plant per square foot, I topped and then tied out the branches.



Thanks for helping me figure it all out, guys.


Post Extras: Print Post  Remind Me! Notify Moderator
Jump to top. Pages: 1

Amazon Shop for: HPS

Cannabis, Marijuana, Ganja & Greens >> Cannabis Cultivation

Similar ThreadsPosterViewsRepliesLast post
* Does a big box NEED to have fans? Ganoderma 799 3 06/19/08 09:57 AM
by Sirius
* Vegging Lights : what are the options? icanfeeltherain 1,889 7 04/02/09 11:32 PM
by impgl
* Which Fan Fits The Bill? Sirius 2,170 11 05/01/08 03:29 AM
by Sirius
* I need an idea of how noisy inline fans are... Help!
( 1 2 all )
erikm 5,896 21 11/16/09 10:50 PM
by coda
* Smallest space for a 600w skullhuman 3,462 10 02/25/10 01:20 PM
by skullhuman
* SolisTek vs Apollo, 600w light systems Icon 655 4 06/11/15 04:27 PM
by Mrshroom
* Need some help with what exaust fan to get erikm 1,508 7 09/04/09 02:50 PM
by Dr. Penguin
* how much fan power do I need? for 600 watt HPS? pftek 5,323 13 12/13/09 05:51 PM
by 81renaissance

Extra information
You cannot start new topics / You cannot reply to topics
HTML is disabled / BBCode is enabled
Moderator: FurrowedBrow, Magash, Dr. Siekadellyk, phychotron
2,642 topic views. 1 members, 70 guests and 62 web crawlers are browsing this forum.
[ Toggle Favorite | Print Topic | Stats ]
Search this thread:

Please support our sponsors.

Copyright 1997-2016 Mind Media. Some rights reserved.

Generated in 0.031 seconds spending 0.005 seconds on 14 queries.