temps

[orion2076]

good advice luke...i guess ta spend a bit more ta cover me bum, in tha long run, the return will be 10 fold...you talk about centrifugal fans with carbon filters...was wondering if anyone could tell me what they are and what they do..ta

[Luke Skywalker]

Centrifugal fans generate pressure as they are scooping and pushing the air around like a jet engine, as opposed to operating like an axial fan and pushing it like a helicopter blade. Pressure is important in carbon filter applications, as they are dense beds of activated carbon which filter out smell/organic particles. If you use an axial fan in anything but the smallest of carbon filters, you'll get a large amount of backwash, where the air is simply not under enough pressure to push through the filter bed of carbon, and simply comes back out the edges of the fan blades. With a centrifugal fan, you are able to eliminate backwash as there is nowhere for the air to go back into, so it is able to generate sufficient pressure to push the air through the filter. Even so, you can expect about 20% loss of airflow through your average filter from the normal speed of the fan.

 

Some small filters can be used with inline-axial fans, which have high speed fanblades and are able to generate enough pressure to push through. The airflow drop off however is much larger than you would have with a centrifugal fan, but in small growroom situations this can be okay if your fan is powerful enough to exhaust your room in seconds or tens of seconds. This leeway between actual airflow requirements and fan speed ensures that if there is any backwash, there will still be enough air being pushed through to ventilate the growroom.

 

Carbon filters are simply a cylinder, (or flat square/rectangular bed) of activated carbon which has an extrememly high surface area due to millions if meso-pores in the carbon granules or pellets. This activated carbon is able to hold onto and filter out organic particles from the air, down to even molecular size. This means that you can eliminate the smell which can lead to detection of your growing space. Anyone who knows what flowering weed smells like will be able to tell what's going on in that house/space, as it's a very distinctive scent.

 

Ozone generators, ionisers and masking scents are also other ways of eliminating or masking the smell of a growroom full of flowering MJ, but carbon filters are usually the method of choice nowadays, due to the excellent effectiveness, relatively cheap cost and ease of use. That and the fact that ozone generators, which are also highly effective, can be harmful to your health if you become overexposed, means that getting a carbon filter for a small, or large growroom is usually what most growers use to remove the scent of their growrooms in full production.

 

Hope that helps, if I've rambled on too much (I do that quite frequently) just ask me to explain something a bit better and I'll see what I can do to make it a little less verbose.

 

If you can afford a centrifugal fan, get one. If not, get a good quality high speed inline axial fan if you intend to use a carbon filter. You can get away with a Hydro-turbo or Air-x-press fan and a small filter if you must, but usually the better option is an inline axial if you have to go that route.

[thc24]

luke skywalker, do you think i can run two centrifugal fans through a "Y" 300mm and into a large carbon filter , already running one centrifugal fan removing air in the room every minute on filter and a second 300 mm axial that is used just to remove heat fast if needed and set on a temp controller along with A/C is used to suck A/C into room faster.

[orion2076]

thanx for tha advice luke. ended up bypassin tha centrifugal fan and tha carbon filter.carbon filter is a bit too expensive and tha centrifugal fan sounded pretty loud...only growin in a cabinet so ended up gettin a 250mm exhaust fan made for continuos use.blows heaps of air compared to the fans i've got.. also got some silica plus to spray on tha plant. helps the plant with heat stress...hopin both of these should ease tha problem...anyone livin in brizzie probably has tha same probs...cheers again...

[orion2076]

hwdy.....bout half hour ago i stuck a 290mm exhaust fan into me cabinet as an exhaust fan....I originaly had 2 small computer fans...this new exhaust fan after bour half an hour dropped the temp by 8 to 10 degrees...should be ideal for tha start of flowering in bout 2 weeks....nowhere near as loud as the computer fans, i paid $110 for it, but results are great...probably gonna buy another to replace the 2 puter inlet fans not only for better temps, but just the noise factor.....

[Luke Skywalker]

You can likely not require a secondary intake fan, just a provision near the base of the cabinet for air to come in. Make sure it's larger than the exhaust fan size though. That said, you can't go wrong having active intake and exhaust, providing you're not pushing in more than you're pulling out, and both fans are of good quality.

 

ended up bypassin tha centrifugal fan and tha carbon filter.carbon filter is a bit too expensive and tha centrifugal fan sounded pretty loud..

 

You'll be requiring some kind of smell removal or masking at some stage. Think about it. Is the cost of a carbon filter, say 150-200 bucks for a 150x300mm unit, worth your entire crop should it be discovered by rippers or the police? I think so, but that's me. Save up for one for later grows if you can. As to sound, you can get silencers for centrifugal fans, and fan speed controllers which will also reduce the sound. Acoustic ducting is wonderful stuff.

 

thc24 Posted Jan 10 2006, 03:32 PM

  luke skywalker, do you think i can run two centrifugal fans through a "Y" 300mm and into a large carbon filter , already running one centrifugal fan removing air in the room every minute on filter and a second 300 mm axial that is used just to remove heat fast if needed and set on a temp controller along with A/C is used to suck A/C into room faster.

 

It depends on what the carbon filter is rated at in maximum airflow, and what the fans are rated at. You can certainly run two fans into one filter if you need to, but generally you'll get the fan to match the filter. If you blow air too fast through a filter you'll have break through and you may as well not have a filter then. The air generally has to contact the carbon for at least 0.1 seconds or some filters can be less than this.

 

So you've got a secondary air-extraction system which doesn't go through the carbon filter? Doesn't that sorta defeat the purpose of the filter?

 

If you can give me some more specs on your filter, fans and perhaps a drawing of the room/s in question I may be able to help some more....

 

Hope that helps.

 

p.s. silica should be utilised for best effect from start to finish in grows, as once it is layed down in the cells of a plant it cannot be translocated to new growth... It will certainly help with stress and with salinity tolerance, as well as making a stronger plant structure though. Can't recommend silica enough, with the best brand IMHO being Silikamajic by flairform. (250ml making up 1250L of working solution @ 2ml per 10L of reservoir solution)

[F420]

silica should be utilised for best effect from start to finish in grows, as once it is layed down in the cells of a plant it cannot be translocated to new growth... It will certainly help with stress and with salinity tolerance, as well as making a stronger plant structure though. Can't recommend silica enough, with the best brand IMHO being Silikamajic by flairform. (250ml making up 1250L of working solution @ 2ml per 10L of reservoir solution)

 

 

Pefectly said mate,

 

one thing with the silica is WATCH THE PH!!! it majorly stuffs the ph up.

[orion2076]

thanx again luke skywalker...will look at centrifugal fans more closely with future setups on tha horizon...with tha 290mm fan i got, not sure if they make a carbon filter small enough for it....was told i'd have to go the bigger centrifugal fans to fit tha carbon filter...hence me sayin bout tha price for tha setup....but if they make a carbon filter to fit tha fan i got, then i'd buy one for sure......there are other ways of gettin rid of tha smell isnt there??...

 

 

hwdy fenengi420...I'm bout 5-6 weeks into veg stage...is it worth startin with tha silica now, or wait till next grow???

 

thanx again guys

[F420]

not really mate, use it from the beginning of your next grow. and make sure you get the flairform one, the others are too weak.

[Luke Skywalker]

suitable Phat filter for that sized wattage would be about 150x600mm, which would definitely require a centrifugal 150mm fan. Anything above a 150x300 filter really requires the high pressure that a centrifugal can acheive.

 

If you do go down the "homemade" route, keep the carbon packed as tightly as you can, and make the surface area of the filter as high as possible if you are using an axial inline fan.

 

Hope that helps.