I have yet to see one that was quiet! The sound of the air coming out is the biggest noice maker. Prob. could hear it in the room next door.

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dont u think the that fan on the filter would be quieter then the inline duct fan?

the force of the air being blown out is going to make some noise after all innless you can run it into your loft or out side some how then you wont here it like mine i have it running into the loft so cant here a thing


thats why its good to get a fan/filter to match the size of your grow room as the bigger the fan = more air being forced = more noise

They do make mufflers for ducts (duct piping)! I hear they work pretty good.

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Indeed they will

You're a little confused on your calculations I'm afraid, however, here's the correct ones to use. To calculate the appropriate fan size for your grow chamber -

1) First find out the cubic capacity of the space. You do this by multiplying the height x depth x width. So far a space 1m wide x 0.5m deep and 2m tall, would be (1x0.5x2) = 1m3.

2) A plant leaf uses all the co2 around it within about 2-3 minutes, so you need to exchange all the air in your chamber at least once every 3 minutes. To calculate that, you divide the exchange times by an hour (60/3=20) and then multiply this by your grow chamber size (20x1) = 20m3. This gives you the minimum flow rate to change all the air in that chamber once every 3 minutes.

3) Now you need to add adjustments for your own circumstances.

a) Add 5% per air cooled HID light and 10-15% per non-air cooled HID light.
b) Add 5% for rooms using co2 enrichment.
c) Add 20% for rooms using a carbon filter
d) Add 25% for hot climates, 40% for hot and humid climates.
e) Add 20-30% total for any ducting that isn't straight, ie any curves in the ducting.

So for our example using one HID light, a carbon filter and kinks in the ducting we're looking at -

20m3 per minute. + 5% for one HID (1) plus 20% for a carbon filter (4) plus 30% for ducting kinks (6). Thats 20+1+4+6=31m3 per minute.

That means you need a fan capable of extracting a minimum of 31m3 per minute flat out. If you intend on using a cheap resistive fan speed controller to adjust the fan speed, you want to be looking at using a range between 1/4 speed and 3/4 speed. At lower than 1/4 speed you'll get fan whine from the cheap resistive fan speed controller, at higher than 3/4 speed you'll get fan noise and air movement rushing noise. So we need a fan capable of moving 31m3 at 100%. We ideally need a fan capable of moving 31m3 at 50% (half way between 1/4 and 3/4 speed) so double the 31m3 to 62m3. That would be the optimum air movement running the fan at it's quietest 50% capacity.

So to convert 62m3 per minute to litres per minute multiply by 16.67. To convert from m3/min to cfm multiply by 35.32.

So for our example we'd need a fan capable of moving around 218cfm.

those muffler work really well, especially the bigger ones, the bigger the better they get as their is more surface for the air to slow down on. the also cut down a tiny bit on small level and big time on the heat signature of the air. BUT those mufflers can get quit worm sometimes too, so the should be a bit covered to for stealth

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keep the thumb green and the gun oiled, !

that has to become a stick about ventilation

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keep the thumb green and the gun oiled, !

arite i think im gonna go with the one off of ebay...im still not sure yet cuz i havent been able to find a nice fan for a good price that has switch to control fan speed..any ideas