Ventilation w/ LED

Hi all,

I'm researching my first grow and it will be with LEDs. Just getting my supply list together so I can figure out my budget.

I want to get your folks' input on ventilation while growing in a Grow Tent. Here are my specifics thus far:

- 2x4' Grow Tent - 5 ft Tall
- LED grow lights from Area 51
- Going to Build a Carbon Filter based on this thread: https://www.rollitup.org/do-yourself/558980-other-best-diy-carbon-filter.html
- Passive Air Intake - Negative pressure on Tent with a fan pulling air out of the tent through the filter.

Now, the questions:

Most of the info I find on ventilation for grow tents factors in heat exhaust from HID lights. With LED lights, since one of the benefits is heat reduction I'd imagine that a less intensive ventilation system is needed than those that are found in abundance on the internet forums. Thinking the ventilation is only needed for proper air circulation (freshness). What do you experienced LED growers recommend for ventilation, as far as cfm is concerned? I've been reading a complete cf refresh every 1-5 minutes, but does that take into account heat exhaustion?

What I ultimately would do with the info is buy the proper powered fan for this setup, based on cfm of fan and cf of tent with consideration of how often the entire volume of air in the tent will need to be refreshed.

Also, what sort of effect does a Carbon filter (like the DIY in the above link) have on a fans cfm rating? If one deduces that a fan of 'x' cfm is needed for a specific grow tent, then how much can one expect the cfm of said fan to be reduced by the resistance of the carbon filter? 1/2 .... more? Is there a formula based on diameter/length of the filter, that someone has found or come up with?


Thanks for your time,

MojoSlim

Bumping Spheda said:

No idea how much a carbon scrubber will kill your cfm's. I'm willing to bet it varies from fan to fan. Some fans even have an on board sensor that monitors the ?air resistance? and work harder if it's not pulling as much air as it thinks it should be. Imo, though, you're over thinking it a little.

Is noise an issue for you?

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Thanks for the response. I tend to over think things. At this point, there is no noise, as I'm in the budgeting phase and have not bought anything, yet. The reason for the question is that I'm trying to find the best fan in terms of cfm for my grow tent and accessories. That way I can know the cost and put it in my budget. As far as noise, I'd like it to be as quiet as possible. At this point, I am not sure what size fan to use (in terms of cfm, at least; I'll be using a 4" diameter duct), and figured if I knew the answer to the above, I could then start pricing fans in that cfm range. I don't want to be underpowered, nor do I want to be overpowered.

Interesting info on the advanced fan options that you mention. Can you recommend a fan for my needs?

I'm also am a little @nal about it because I cannot buy any of my supplies (besides nutrients) in town due to lack of availability and incredible price gouging. I'll need to buy online and don't have the luxury of easily replacing things that are inadequate; I'd prefer to get it down pat from the get go.


Regards,
Mojo

Whoops. Deleted my post because I felt it was beside the point and didn't help you at all. Didn't get away with it. >< Anyway, that's a much better response than I had hoped for!

Well, since you said you want it to be as quiet as possible I'll recommend the Panasonic WhisperCeiling series of fans. Dead quiet fans, well built. The only problem is you'd have to tweak your design, or modify the fan's intake. I'd recommend having the fan inside the tent pushing air into the scrubber. Check them out, I think the 50cfm or 80cfm flavor would perform well in your setup.

Edit:
Hope I don't get busted for this.
https://www.icmag.com/ic/showthread.php?t=45196
DIY carbon scrubber with a WhisperCeiling.

Bumping Spheda said:

Whoops. Deleted my post because I felt it was beside the point and didn't help you at all. Didn't get away with it. >< Anyway, that's a much better response than I had hoped for!

Well, since you said you want it to be as quiet as possible I'll recommend the Panasonic WhisperCeiling series of fans. Dead quiet fans, well built. The only problem is you'd have to tweak your design, or modify the fan's intake. I'd recommend having the fan inside the tent pushing air into the scrubber. Check them out, I think the 50cfm or 80cfm flavor would perform well in your setup.

Edit:
Hope I don't get busted for this.
https://www.icmag.com/ic/showthread.php?t=45196
DIY carbon scrubber with a WhisperCeiling.

Click to expand...

I guess I'm pretty quick on the reply button

Thanks again for responding. I'll check out your info. Tweaking and modifying setups seems to come with the territory. That setup for the whisper fan looks like fun. Did I mention I like to build stuff? Not sure if its a mental disorder, but I need to constantly be doing stuff with my hands, which primarily is guitar playing; Building grow supplies is right up my alley!


P.S., I can delete your quote in my last post, if you want the record of that post expunged?

Nah, don't worry about deleting the quote. If other people can benefit from what's been said then sweet.

Oh, and I guess the WhisperCeiling was the fan that adjusts to air resistance. Completely forgot what model I was thinking of. It sounds like a good match for you so long as you can spare the space inside the tent.

GL and happy growin'.

I tell ya I'm shocked more people don't build these things. I built mine, but I was lazy about the whole computing the CFM thing so I bought a much larger induction fan, (600 CFM), than I needed, (6'x6'x6' flowering tent), which brings me to the point of my post, don't forget to buy a good fan controller because you'll want to tweak how fast the air is moving through the carbon. Too fast through loosely packed carbon and it won't work very well. There are formulas for computing what you want, but the DIY nature throws a bit of a monkey wrench into it unless you're building it to some exacting standard. Plus if you think long term, a bigger induction fan running at reduced load is probably a good thing, especially for the cheaper fans. Still some people gotta do it right. You one of those freaks ? LOL

These look cool for that, I think.

http://www.circuitspecialists.com/variac-variable-ac-ps05kva.html

I like your idea of going a little over your current needs, FranJan. I got the FV-08VQ5 (80cfm) despite only really needing about 20-30cfm. You never know, it could come in handy someday.

Grozone TV1 or 2 controller's, 40-100 bucks depending on model and where from, put the sensor in environment and plug your fan into the controller- it will adjust the fans speed according to the temperature and setpoints, think it goes from 15-100% speed, just put it at the lowest possible % and it will adjust all day long.

EDIT: "Grozone multimode Controller (Day/Night)" or TV1/TV2

6" fan with a controller should be good.

What you are trying to control is VPD (Vapor pressure deficit) Google it, more than temperature.

VPD limits are much tighter than temp limits with the plant. Indoor tends to be too humid, possibly causing bud rot and mold.
Proper VPD increases health and harvest.

Just an FYI........Reducing your fan speed on a on a fan that is designed to run at a SET cfm/amp load is a big NO NO

http://cannabis.com/growing/electric-Can_I_use_a_dimmer_switch_to_control_the_speed_of_my_fan.html <<In case you think I'm lying

make sure it has a multi-speed motor before reducing it's load.......happy shopping

PSUAGRO. said:

Just an FYI........Reducing your fan speed on a on a fan that is designed to run at a SET cfm/amp load is a big NO NO

http://cannabis.com/growing/electric-Can_I_use_a_dimmer_switch_to_control_the_speed_of_my_fan.html <<In case you think I'm lying

make sure it has a multi-speed motor before reducing it's load.......happy shopping

Click to expand...

Thanks for jumping in. I was thinking about the load draw a little bit earlier. I used to screw around with making power soaks for my guitar amplifiers using light dimmers (read about it from an Eddie Van Halen article) so that I could drop the watts down for living room volume playing. It definietly stresses the power transformer, and also burns through tubes/valves faster. Thought this is probably going to happen on the fan, too (the motor, that is). Which brought me back to researching the fan cfm to grow room volume ratio.

btw, didn't think you were lying, and I appreciate the link to that info, all the same. My view is that a lie is a 2 part system; saying something false on one side, and believing something false on the receiving end; it ain't a lie till someone believes it.

Do other LED users change anything about their ventilation setup, due to decrease in temperature management needs? What sort of ventilation system are other LED grow light users implementing in a small grow tent environment, such as the one I'm currently contemplating?

Thanks for all the thoughtful input so far. Saturday research day!

PSUAGRO. said:

Just an FYI........Reducing your fan speed on a on a fan that is designed to run at a SET cfm/amp load is a big NO NO

http://cannabis.com/growing/electric-Can_I_use_a_dimmer_switch_to_control_the_speed_of_my_fan.html <<In case you think I'm lying

make sure it has a multi-speed motor before reducing it's load.......happy shopping

Click to expand...

Exactly. It's not always an option. Depends on the fans. My manufacturer recommends certain types of controllers and tells you which ones to avoid. Doesn't Dawg have some ultra stoopid quiet fan P?

http://www.amazon.com/Panasonic-FV-08VQC5-WhisperSense-Ventilation-Technology/dp/B005FT1406

Whisper Sense is a single-speed, ventilation fan which is enabled by any of the three following methods: motion on/motion off, motion on/humidity off or humidity on/humidity off. The humidity sensor is adjustable between 30-Percent and 80-Percent RH and factory set for 50-Percent. The fan can be set to run 0.5 to 60 minutes after the motion sensor ceases detection or the humidity returns to the set point. The humidity sensor continues to check that the moisture levels conditions have been met.

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or maybe

http://compare.ebay.com/like/110948770976?var=lv&ltyp=AllFixedPriceItemTypes&var=sbar

johnluke said:

ok well i got a 10x10 tent and am gonna start running a black dog platinum XL LED 1500 watt it seems like everyones buying LEDs and not modifying their tent to keep up with this technological invention in lighting! anyone have any input on what i would be lacking if i didn't vent my grow room????????????

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I don't know what area you are planning on that 1500 watt LED covering but if it's more than a foot larger each way than the dimensions of the fixture, you should get a light mover. LED doesn't just replace HID as a point source;HID spreads light much more than LED does so in effect LED grows well what is under it and a little more but not a lot more thus a light mover so you can effectively use all that light.

I run a 4" vortex inline fan out of a 4x4 with two 180w progrow's. It sucks the life out of the tent. I utilize a variac controller (about $60) with my fan and it gives me total, very smooth control. 100% output has not been needed. The variac has been one of my favorite purchases. Next, I will bring in the progrow 260w with the other two lights for autoflowers. I don't expect it will make a difference with the exhaust either. I hang 3 six inch fans for blow. I now hang my inline fan and carbon filter with bungee cords and that has worked out really well. If I need heat, I run a small radiator heater (butted to vent port) in the shell of a wooden, 2 drawer file cabinet. The vortex sucks in the heat keeping it nice and toasty. Good luck with your grow.

PositiveGreen said:

I run a 4" vortex inline fan out of a 4x4 with two 180w progrow's. It sucks the life out of the tent. I utilize a variac controller (about $60) with my fan and it gives me total, very smooth control. 100% output has not been needed. The variac has been one of my favorite purchases. Next, I will bring in the progrow 260w with the other two lights for autoflowers. I don't expect it will make a difference with the exhaust either. I hang 3 six inch fans for blow. I now hang my inline fan and carbon filter with bungee cords and that has worked out really well. If I need heat, I run a small radiator heater (butted to vent port) in the shell of a wooden, 2 drawer file cabinet. The vortex sucks in the heat keeping it nice and toasty. Good luck with your grow.

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OK, my setup changed somewhat over the past few days. The above is only if you are running "short ducting & led lights" with a 4" inline. I decided to upgrade to a 6" vortex (Phresh 6x24) while running longer ducting to a bathroom vent with reducer, so it was prudent to go with the next size up.