Idid there in a pic i put up an hour and a half agoBTW
Would this work
- Thread starter Chongstar
- Start date
Indefinately
Well-Known Member
Thankx vro, means alot
Indefinately
Well-Known Member
I think white widow being an Indica dominant plant will grow better as a sog.
Where as green crack being a sari a May grow a little taller.
Not sure, as I haven't grown them personally.
Just my opinion.
Indefinately
" Let there be Green in 2016 "
Indefinately
Well-Known Member
Just found an interesting article on Ventilation :
How to calculate ventilation
We asked two experienced growers (Dan from Oregon and Fred from The Netherlands) to face off with their different opinions on how to calculate your fan requirements.
Dan's Method - Calculating By Room Volume
You will find many calculations on the web for sizing a fan for ventilating indoor gardens; however, what many of these calculations fail to take into consideration is the friction loss on carbon filters and increased temperatures from HID lights. So here's my calculation method which you can use as a guide for sizing an exhaust fan for a growing area (keep in mind that this calculation will give you the lowest required CFM (Cubic feet of air per minute) required to ventilate the indoor garden.)
Step 1: Room Volume First the volume of the room needs to be calculated. To calculate multiply length x width x height of growing area e.g. A room that is 8' x 8' x 8' will have a volume of 512 cubic feet.
Step 2: CFM Required Your extraction fan should be able to adequately exchange the air in an indoor garden once every three minutes. Therefore, 512 cubic feet / 3 minutes = 171 CFM. This will be the absolute minimum CFM for exchanging the air in an indoor garden.
Step 3: Additional factors Unfortunately, the minimum CFM needed to ventilate a indoor garden is never quite that simple. Once the grower has calculated the minimum CFM required for their indoor garden the following additional factors need to be considered:
Number of HID lights — add 5% per air cooled light or 10-15% per non-air cooled light.
CO2: add 5% for rooms with CO2 enrichment
Filters: if a carbon filter is to be used with the exhaust system then add 20%
Ambient temperature: for hot climates (such as Southern California) add 25%, for hot and humid climates (such as Florida) add up to 40%.
An Example In our 8' x 8' room we have 2 x 1000w air cooled lights, and we plan to use a carbon filter. We also plan to use CO2 in this room. The ambient temperature is 90 °F (32°C), however, we will be using air from another room that is air-conditioned. Here's the minimum required CFM to ventilate room:
1) Calculate the CFM required for room (see above.)
2) Add 10% (for 2 air cooled lights.)
3) Add 5% of original CFM calculation (For CO2.)
4) Add 20% of original CFM calculation for Carbon Filter.
5) Air is coming from air-conditioned room so no need to add any other percentages.
6) CFM = (171 CFM) + (171CFM x 10%) + (171 CFM x 5%) + (171CFM x 20%) + ( 0 )= 231 CFM.
This is the absolute minimum CFM required to ventilate your room.
The next step might seem to match the closest fan to this CFM. However, for this example I'd choose a six inch fan with a CFM of around 400 or more, and a 6 inch carbon filter to match. The extra CFMs may seem a bit excessive (calculations on most indoor gardening websites would recommend a 4" fan and a 4" carbon filter) but it's always better to over-spec since we need to compensate for air resistance in ducting too.
Also, as we are using a carbon filter we will need to match the fan with the filter so that the fan that will neatly fit onto the filter.
If all the variables are kept the same and we changed the room size from 8' x 8' to a 12' x 12' then the minimum required CFM would be 519 CFM.
The All-Important Inflow!
An intake port can be anything from a gap under the door to an open window - even a hole in the wall. The best place for an intake port is diagonally opposite from your exhaust fan; that way, air has to pass across the entire room - very efficient. You can put a piece of screen over the opening to keep insects and animals out, a piece of A/C filter to keep dust out, or a louvered shutter or backdraft damper that opens when the fan turns on and closes when it turns off. You can also use a motorized damper. This gets installed in-line with your ducting and is plugged into whatever device controls your exhaust fan. When your fan turns on, it allows air to pass. When your fan shuts off, it seals completely, preventing CO2, air, etc. from passing. You can get creative with these devices and use one fan to control two rooms, etc.
One additional note about intake ports - you will see much better results from your exhaust system if you install a second fan to create an active (as opposed to passive) intake system. Normally, when your exhaust fan sucks air out of your room, air is passively going to get sucked back into the room. By installing a second fan on the intake side, you will reduce the amount of negative pressure created in the indoor garden, thereby cutting down greatly on the amount of work the exhaust fan has to do and allowing much more air to pass through. If you're not sure or you don't want to spend the money, start out with just an exhaust fan. If it's not performing as well as you thought it would, try adding an intake fan - you'll smile when you see the difference!
Fred's Method - Calculating By Wattage
Hello there. First off, I'm used to working with Celsius, not Fahrenheit, but I've done my best to provide formulas for both. My method for calculating fan requirements does not cover active cooling with air conditioning systems or cool-tube designs. We're talking about everyday grow chambers here, totally enclosed for airflow control, with no large amounts of radiant heat into or out of the box. Your mileage may vary some for these reasons.
RIGHT THEN, LET'S GET STARTED:
1) Start at the beginning and design this right! Before you even buy or cut anything for your new project, determine the highest temperature that your intake air will ever be when lights run. Call this T (inlet).
2) Use these formulas to determine difference in temperature you can tolerate. 80°F (27°C) is just about the optimal for growing most plants. You can go up to 86°F (30°C) if you have to, but aim for 80°F (27°C).
Tdiff = 27 °C – T (temperature of inlet air)
3) Add up wattage for all power sources in your indoor garden. Lights, pumps, heaters, humidifier, radio, coffee maker, whatever! Add it ALL up and call it Watts. If it is on for more than three minutes and uses more than a watt, add it up. This will make your number worst-case and therefore a conservative value.
4) Compute the absolute minimum fan power you will need using the following formulas. Fan power is measured in the amount of air (cubic feet) shifted per minute. The formula below is the minimum fan rating you must have to achieve your temperature goals. You will have to increase fan power to compensate for duct constriction, small inlets, carbon scrubbers, screens, or other items that block airflow.
CFM = 1.75 x Watts /Tdiff (in Celsius)
If you prefer to work in Fahrenheit, try this formula:
CFM = 3 x Watts / Tdiff (in Fahrenheit)
5) Get at least this fan power or don't come and ask questions! If you are going to have more than one fan, they should be mounted side-by-side rather than inline if you want to add their different CFM ratings. For inline fans, use the lowest airflow rating of all fans in the path. A fan on the inlet and a fan on the exhaust of the box are considered inline fans. Fans just circulating air inside the indoor garden should not be counted for airflow but must be included in your initial wattage calculations.
OK, TO SEE THESE FORMULAS IN ACTION WE'RE GOING TO HAVE TO DO A LITTLE NUMBER CRUNCHING:
An Example Ok, let's say you have 2000 watts in a 8 foot by 8 foot room with an 8 foot ceiling height.
So what amount of air do I need to move to keep the room at 82°F (28°C)? My incoming air temperatures are 68°F (20°C) during the lights on period.
Tdiff = 28 – 20 = 8°C
For Celsius the formula comes out at: CFM = 1.75 x 2000 / 8 = 438 CFM
For Fahrenheit we get the following: Tdiff = 82 – 68 = 14°F CFM=3x2000/14=429 CFM
Remember, Tdiff shows how much your temperatures will rise above your inflow air temperature for a given wattage and air movement.
If you are adding any carbon scrubbers or extensive ductwork, this is where you add to the fan size to account for air pressure losses. You have to move this many CFM, or the numbers don't come out right. Exactly how much these items diminish your airflow depends on your exact configuration and is beyond the scope of this introductory article!
What to do when your outside temperatures are higher than your maximum allowed indoor garden temperatures!
YOU HAVE A FEW CHOICES:
1) Stop growing for a while till things cool off or try running your grow lamps at night when inlet air will be cooler.
2) Reduce your lighting to drop the heat load. Not good if the incoming air is already over critical when it arrives in the box. Might be possible if the inlet air temperature is lower but you are running too many lights to keep up with the cooling.
3) Use active air conditioning.
Okay, there you have it – two very different approaches to calculating your extraction requirements. What do you think? Do you prefer either or neither of these approaches? Or perhaps a combination of the two?
How to calculate ventilation
We asked two experienced growers (Dan from Oregon and Fred from The Netherlands) to face off with their different opinions on how to calculate your fan requirements.
Dan's Method - Calculating By Room Volume
You will find many calculations on the web for sizing a fan for ventilating indoor gardens; however, what many of these calculations fail to take into consideration is the friction loss on carbon filters and increased temperatures from HID lights. So here's my calculation method which you can use as a guide for sizing an exhaust fan for a growing area (keep in mind that this calculation will give you the lowest required CFM (Cubic feet of air per minute) required to ventilate the indoor garden.)
Step 1: Room Volume First the volume of the room needs to be calculated. To calculate multiply length x width x height of growing area e.g. A room that is 8' x 8' x 8' will have a volume of 512 cubic feet.
Step 2: CFM Required Your extraction fan should be able to adequately exchange the air in an indoor garden once every three minutes. Therefore, 512 cubic feet / 3 minutes = 171 CFM. This will be the absolute minimum CFM for exchanging the air in an indoor garden.
Step 3: Additional factors Unfortunately, the minimum CFM needed to ventilate a indoor garden is never quite that simple. Once the grower has calculated the minimum CFM required for their indoor garden the following additional factors need to be considered:
Number of HID lights — add 5% per air cooled light or 10-15% per non-air cooled light.
CO2: add 5% for rooms with CO2 enrichment
Filters: if a carbon filter is to be used with the exhaust system then add 20%
Ambient temperature: for hot climates (such as Southern California) add 25%, for hot and humid climates (such as Florida) add up to 40%.
An Example In our 8' x 8' room we have 2 x 1000w air cooled lights, and we plan to use a carbon filter. We also plan to use CO2 in this room. The ambient temperature is 90 °F (32°C), however, we will be using air from another room that is air-conditioned. Here's the minimum required CFM to ventilate room:
1) Calculate the CFM required for room (see above.)
2) Add 10% (for 2 air cooled lights.)
3) Add 5% of original CFM calculation (For CO2.)
4) Add 20% of original CFM calculation for Carbon Filter.
5) Air is coming from air-conditioned room so no need to add any other percentages.
6) CFM = (171 CFM) + (171CFM x 10%) + (171 CFM x 5%) + (171CFM x 20%) + ( 0 )= 231 CFM.
This is the absolute minimum CFM required to ventilate your room.
The next step might seem to match the closest fan to this CFM. However, for this example I'd choose a six inch fan with a CFM of around 400 or more, and a 6 inch carbon filter to match. The extra CFMs may seem a bit excessive (calculations on most indoor gardening websites would recommend a 4" fan and a 4" carbon filter) but it's always better to over-spec since we need to compensate for air resistance in ducting too.
Also, as we are using a carbon filter we will need to match the fan with the filter so that the fan that will neatly fit onto the filter.
If all the variables are kept the same and we changed the room size from 8' x 8' to a 12' x 12' then the minimum required CFM would be 519 CFM.
The All-Important Inflow!
An intake port can be anything from a gap under the door to an open window - even a hole in the wall. The best place for an intake port is diagonally opposite from your exhaust fan; that way, air has to pass across the entire room - very efficient. You can put a piece of screen over the opening to keep insects and animals out, a piece of A/C filter to keep dust out, or a louvered shutter or backdraft damper that opens when the fan turns on and closes when it turns off. You can also use a motorized damper. This gets installed in-line with your ducting and is plugged into whatever device controls your exhaust fan. When your fan turns on, it allows air to pass. When your fan shuts off, it seals completely, preventing CO2, air, etc. from passing. You can get creative with these devices and use one fan to control two rooms, etc.
One additional note about intake ports - you will see much better results from your exhaust system if you install a second fan to create an active (as opposed to passive) intake system. Normally, when your exhaust fan sucks air out of your room, air is passively going to get sucked back into the room. By installing a second fan on the intake side, you will reduce the amount of negative pressure created in the indoor garden, thereby cutting down greatly on the amount of work the exhaust fan has to do and allowing much more air to pass through. If you're not sure or you don't want to spend the money, start out with just an exhaust fan. If it's not performing as well as you thought it would, try adding an intake fan - you'll smile when you see the difference!
Fred's Method - Calculating By Wattage
Hello there. First off, I'm used to working with Celsius, not Fahrenheit, but I've done my best to provide formulas for both. My method for calculating fan requirements does not cover active cooling with air conditioning systems or cool-tube designs. We're talking about everyday grow chambers here, totally enclosed for airflow control, with no large amounts of radiant heat into or out of the box. Your mileage may vary some for these reasons.
RIGHT THEN, LET'S GET STARTED:
1) Start at the beginning and design this right! Before you even buy or cut anything for your new project, determine the highest temperature that your intake air will ever be when lights run. Call this T (inlet).
2) Use these formulas to determine difference in temperature you can tolerate. 80°F (27°C) is just about the optimal for growing most plants. You can go up to 86°F (30°C) if you have to, but aim for 80°F (27°C).
Tdiff = 27 °C – T (temperature of inlet air)
3) Add up wattage for all power sources in your indoor garden. Lights, pumps, heaters, humidifier, radio, coffee maker, whatever! Add it ALL up and call it Watts. If it is on for more than three minutes and uses more than a watt, add it up. This will make your number worst-case and therefore a conservative value.
4) Compute the absolute minimum fan power you will need using the following formulas. Fan power is measured in the amount of air (cubic feet) shifted per minute. The formula below is the minimum fan rating you must have to achieve your temperature goals. You will have to increase fan power to compensate for duct constriction, small inlets, carbon scrubbers, screens, or other items that block airflow.
CFM = 1.75 x Watts /Tdiff (in Celsius)
If you prefer to work in Fahrenheit, try this formula:
CFM = 3 x Watts / Tdiff (in Fahrenheit)
5) Get at least this fan power or don't come and ask questions! If you are going to have more than one fan, they should be mounted side-by-side rather than inline if you want to add their different CFM ratings. For inline fans, use the lowest airflow rating of all fans in the path. A fan on the inlet and a fan on the exhaust of the box are considered inline fans. Fans just circulating air inside the indoor garden should not be counted for airflow but must be included in your initial wattage calculations.
OK, TO SEE THESE FORMULAS IN ACTION WE'RE GOING TO HAVE TO DO A LITTLE NUMBER CRUNCHING:
An Example Ok, let's say you have 2000 watts in a 8 foot by 8 foot room with an 8 foot ceiling height.
So what amount of air do I need to move to keep the room at 82°F (28°C)? My incoming air temperatures are 68°F (20°C) during the lights on period.
Tdiff = 28 – 20 = 8°C
For Celsius the formula comes out at: CFM = 1.75 x 2000 / 8 = 438 CFM
For Fahrenheit we get the following: Tdiff = 82 – 68 = 14°F CFM=3x2000/14=429 CFM
Remember, Tdiff shows how much your temperatures will rise above your inflow air temperature for a given wattage and air movement.
If you are adding any carbon scrubbers or extensive ductwork, this is where you add to the fan size to account for air pressure losses. You have to move this many CFM, or the numbers don't come out right. Exactly how much these items diminish your airflow depends on your exact configuration and is beyond the scope of this introductory article!
What to do when your outside temperatures are higher than your maximum allowed indoor garden temperatures!
YOU HAVE A FEW CHOICES:
1) Stop growing for a while till things cool off or try running your grow lamps at night when inlet air will be cooler.
2) Reduce your lighting to drop the heat load. Not good if the incoming air is already over critical when it arrives in the box. Might be possible if the inlet air temperature is lower but you are running too many lights to keep up with the cooling.
3) Use active air conditioning.
Okay, there you have it – two very different approaches to calculating your extraction requirements. What do you think? Do you prefer either or neither of these approaches? Or perhaps a combination of the two?
That was an interesting read, Freds mrthod seemed a little confusing me to me? And yeah i hope the white widow is good as well as gc for SOG. What srains do you use?
Al b fuct is funny! Ive been reading these posts, very informative thank you!
Would like to ask one more thing. Now i am going to do a 2k watt flowering room in a grow tent! The grow tent is 10 feet by 5 feet by 6 1/2 feet. So according the the article i just read above, using DANS method, i added an additioal 5% for cool tubes and 20% for hot wearher (summer), and what i came to is a minimim of around 400 sq feet for my inline exhaust fan out the tent. Would this be enough to cool 2 1kw lights on cooltubes connected to a carbon filter? Or should i get another inline exhaust fan just incase? Also as far as intake goes, can i just use like a small 240 duct fan? Or shoukd i pick up something bigger? After this i should be ready to go! Thanks in advance, please let me know
Indefinately
Well-Known Member
Hey Chong,
Pretty much,
Your suppose to add 5% per "cool tube" , so your suppose to add 10% since you are running 2 x 1k lights.
But your close enough, I guess.
Are you not using a carbon filter?
If so, that's meant to add another 20%
Always go over kill on fans.
Always Better to be bigger.
If your tent is going to be ten foot by 5 foot.
What size flood and drain tables are you going to fit in there?
Or are you using another system?
Indefinately
" Let there be Green in 2016 "
I will be using the tables that you reccomended, which both combine and will take up about 36 sq ft of the tent. And i am going to defenitly use a carbon filter, so are you saying its 20% extra if i use the filter or 20% extra if i dont. If its because im going to use it then that will bring my grand total to like about 600 cfm? I already havr the two inline fans that are 1000 cfm each but, the the width on then are like 12' (cool tubes are 6') and they are more than twice the minimum, wouldnt that be an overkill?
Indefinately
Well-Known Member
Hey Chong,
As per the above calculation, it states:
Filters: if a carbon filter is to be used with the exhaust system then add 20%
There are flanges to reduce the size of your fans to the desired size.
If you have calculated that you require 600 cfm after adding the 20% for the carbon filter.
Just get a speed controller for your fan and run in at 60% since yours is a 1000.
That way imply have the option of increasing the speed if required later.
For your cool tubes, you definitely won't need a 1000cfm fan. A 6 inch fan will do the job for that easy, even smaller really.
what size exactly are the tables you are looking at? Do you have a link?
Two tables ( 2m x 1m ) won't fit in your Tent.
Your tent is only 3m x 1.5 ( 10 foot by 5 foot ).
Talk metres ( metric ) so I don't have to keep converting to foot all the time.
I could not be $&@$ed converting it all the time.
Lol
Have you planted those seeds in some coco yet?
Indefinately
"Let there be Green in 2016 "
Lol no. Thats a great idea about the fan controller! I was planning on attatching the filter, silencer, and cool tubes all to the same 1000 cfm exhaust. Can i do this? And just monitor the heat via fan controller?
Also, i was looking at the 4x8 flood tables and just using both lights on the same table. I should be able to fit about 80 something clones on that right?
Indefinately
Well-Known Member
Hey bud,
Work it out in meters , or work it out your self bud.
Trying to help as much as I can.
The tables I suggested for each light to have enough spread for each table are 2m x 1m.
2 of those tables simply won't fit in the tent that you suggested.
Secondly, the video Justugh posted explained thoroughly how to set up fans for closed and open rooms.
Did any of them have the carbon filter attached to the lights? None of them.
Have you planted those seeds yet?
Last photo had a big tap root......
Good luck with everything
Be thorough in reading and understanding what ever info you are provided.
Justugh Videos were excellent!
The calculation for ventilation above was spot on.
Just need to implement them as close as possible to the suggestions.
Indefinately
"Let there be Green in 2016 "
Ur right, I just thought since it was in a tent the rules changed a bit and also the 1000 cfm is much stronger then what I needed so I figured it could pull through all four and still be effective. OK so scratch that. So are you saying I should have 2 inline fans for the tent? If so should I split the cfms between the two fans? Like one fan does the cool tubes and the other the filter?
Sorry about that, yeah the tables are 1.2192 by 2.4384 sq meters
Sorry about that, yeah the tables are 1.2192 by 2.4384 sq meters
Indefinately
Well-Known Member
Closed loop for lights as per the video
Dimension of tables doesn't work
Get smaller tables.
Need to be about 2 m x 1m for each light to be effective. Smaller is better in this case.
As lights won't be effective on larger tables.
You need two table to fit in your tent.
So work it out backwards.
Indefinately
" Let there be Green in 2016 "
Closest I could find is a 3x6 table which would convert into a .9x 1.8 meter table. What size rez would you use for that
Indefinately
Well-Known Member
Hey Chong ,
Perfect size!
200 litre reservoir would work well.
Indefinately
" Let there be Green in 2016 "
Perfect size!
200 litre reservoir would work well.
Indefinately
" Let there be Green in 2016 "