Which fan to buy. Advice greatly appreciated.

[Jake hammer]

I'm thinking of upgrading my extractor fan in my 4ftx4ftx6.6ft tent.
I'm currently using a cheaper 5 inch one which does the job but just about so want better.
I'm looking at using a ram 6 or 8 one.
Is 8 inch too much with that grow space. I will also be buying a speed controller.
Does anyone know about the ram fans.
Are they noisey or pretty quiet.
Growning using hps BTW.
Based in UK if anyone got better suggestions instead of the ram range.

[Cannabug]

Alright Jake I'm no expert mate but that 8" might be a tad powerful imo. Ram fans aren't too bad from what I've seen about here but the most commonly used would be the RVK range. They seem pretty solid. I use a 5" RVK I know theres 2 types in the 5" range and I paid about £15 extra to get the more powerful one. I currently use it in my 1.2m x 1.2m tent and its able to pull all 4 sides in while in operation. That's with one of the mesh side screens open aswell.
Someone who knows the science of cubic airflow will give you a more detailed input on the matter bud

[Jake hammer]

Alright Jake I'm no expert mate but that 8" might be a tad powerful imo. Ram fans aren't too bad from what I've seen about here but the most commonly used would be the RVK range. They seem pretty solid. I use a 5" RVK I know theres 2 types in the 5" range and I paid about £15 extra to get the more powerful one. I currently use it in my 1.2m x 1.2m tent and its able to pull all 4 sides in while in operation. That's with one of the mesh side screens open aswell.
Someone who knows the science of cubic airflow will give you a more detailed input on the matter bud

Thanks for replying bud,
I'll take a look at the rvk range now. I know I'm going onto a different topic now but do u keep your mesh open day and night. I worry about light leaks, I do too when I see the light shine tho the zipper teeth with lights on.

[Jake hammer]

Liking the looks of those fans ??

[Cannabug]

Thanks for replying bud,
I'll take a look at the rvk range now. I know I'm going onto a different topic now but do u keep your mesh open day and night. I worry about light leaks, I do too when I see the light shine tho the zipper teeth with lights on.

No worries mate. I've only just opened them as the uk temps have gone up abit since last week but I know what you mean with light leaks. Mine are still in veg atm and lights on 24/7 so all good for now
I'm just after reading a diary earlier from a well known moderator that his fan was pretty new and packed in midway through flower his was different to an RVK. You wont go far wrong with the RVK's Jake

[Mac]

4x4x6.6 = 105.6cubic feet (2.99 cubic meters)

You need to replace the air in your tent at least once per minute whilst maintaining negative pressure on the tent to keep the smell contained (sucking air in thru all the vents, if your tent walls bow inwards you have negative pressure, if they bow out you have positive pressure leading to smell escape). So we multiply by 60 to work out the hourly amount of air that needs moving.

60 x 105.6 = 6336 cubic feet per hour (179 cubic meters per hour)


I generally add 50% extra on to allow for ducting bends and filter resistance (269m3/h)


So your fan needs to move at least 270m3/h to move all the air once per minute.


Most fans will tell you their ratings/figures on the website/box.


If you buy a fan that can do say 600m3/h then you can run it at 50% speed (quiet!!!) with a controller and still move more than the required amount of air.

Large fans running slowly make less noise than small fans running quickly.

[Farmer Geddon]

rvk is the industry standard. They get fitted to buildings and are then left running for many a year. The 6" rvk in my cellar has been running for 15+ years as the cellar is also my workshop. The high power versions are for using a carbon filter.

If you have room for an 8" rvk and filter then why not? With a bigger filter, you get more carbon per £. It will take up a fair bit of room in a tent though. ime, a 6" rvk high power is fine for up to an 8'x4' space. With the usual caveat of keeping the ducting run minimal.

If using a smaller fan, what will improve airflow for only a few quid is to use 8" ducting with a reducer at each end. Here's a rough calculation of the area of various ducting sizes: 4" = 12.5 sq in. 5" = 20 sq in. 6" = 28 sq in. 8" = 50 sq in.

The best fan speed controllers are magnetic. ie. an old fashioned transformer. Zero hum. Most grow shops sell stepped transformers to give you a choice of speeds. Reassuringly expensive.

[Bud Lightyear]

I ran the same size tent a few year back with an Ruck 200mm 8" L high power fan on a variac controller with passive intake...Running a single 1000w HPS lamp, worked really well...I like to over engineer things, I would rather have a higher powered fan running slower than a smaller fan screaming its bollocks off...

You can see the setup here...https://www.thctalk.com/cannabis-for...lent-Ruck-200L


Regards BL

[Jake hammer]

Thank you guys for all the help. I know with a speed controller it helps with noise on the lower setting but would a 8inch be a lot more noisey than a 6 inch of the same model.
Say rvk 6 vs rvk 8. Both same models.

[IceCalibur]

Thank you guys for all the help. I know with a speed controller it helps with noise on the lower setting but would a 8inch be a lot more noisey than a 6 inch of the same model.
Say rvk 6 vs rvk 8. Both same models.

Both on full blast?..yes, but as said above, you'll be able to turn down the 8" lower than the 6" and that will result in less noise