Grow Room Passive intake vs active

[bad dragon bzzz]

a 4 inch fan with the restriction of a filter = 3" of suck.a dirty filter and its = 2" of suck
add a active intake 4" the sides will buldge cause there be more blow than suck,both 4" but ext has restriction of carbon filter.
is the persil white cover on the outside of filter now this shade ? this was mine the first time i looked (10 months)...........we meant to wash em every few months.....(the carbon will block up slowly over time as soon as you start using it)......but i just throw the whole thing out every year,and for £20 im happy with that.
id prefare to have 2 ext fans and use a crack in the zip/door as the passive.
short ducting with 1 bend shouldnt make much difference.infinaty not the cheapest and with 205 the numbers ok.
ya dont have a massive filter by any chance ?
keep er lit

 

[StevOrganic]

Your tent should be sucked in. I loose 4" on a side when the extractor running 100%. If your not pulling in the walls of the tent, your extraction fan is too small or there is an issue with the unit.
Left as it is, your gonna have mold/rot issues... maybe not this round, but it will happen. Some genetics are more resistant, but needs to be addressed.
It's too late at this point, but there is a product that I tested last fall out of Canada called Rotblock. It works... but needs to be used from flower initiation. Went all thru flower with silly high rH #s, no issue.

The filter is only a little dirty still fairly white so not sure if thata the reason why but the walls of the tent are not sucking in so something is up.. the house doesn't stink but you can smell it outside the room which means its obviously not extracting.. i can keep the humidity around 55 lights on so there is some extraction taking place i will update later on i will take off the sleeve and do some poking about thanks guys.

 

[StevOrganic]

a 4 inch fan with the restriction of a filter = 3" of suck.a dirty filter and its = 2" of suck
add a active intake 4" the sides will buldge cause there be more blow than suck,both 4" but ext has restriction of carbon filter.
is the persil white View attachment 1224607 cover on the outside of filter now this shade ? View attachment 1224606 this was mine the first time i looked (10 months)...........we meant to wash em every few months.....(the carbon will block up slowly over time as soon as you start using it)......but i just throw the whole thing out every year,and for £20 im happy with that.
id prefare to have 2 ext fans and use a crack in the zip/door as the passive.
short ducting with 1 bend shouldnt make much difference.infinaty not the cheapest and with 205 the numbers ok.
ya dont have a massive filter by any chance ?
keep er lit

The filter is quite big its a 4 inch Rhino Pro carbon filter

 

[derek420colorado]

The filter is only a little dirty still fairly white so not sure if thata the reason why but the walls of the tent are not sucking in so something is up.. the house doesn't stink but you can smell it outside the room which means its obviously not extracting.. i can keep the humidity around 55 lights on so there is some extraction taking place i will update later on i will take off the sleeve and do some poking about thanks guys.

Try taking the filter off for a second and see if it gives you negative pressure. If it doesn’t then the problem is your extraction fan.

 

[Arthur]

The filter is only a little dirty still fairly white so not sure if thata the reason why but the walls of the tent are not sucking in so something is up.. the house doesn't stink but you can smell it outside the room which means its obviously not extracting.. i can keep the humidity around 55 lights on so there is some extraction taking place i will update later on i will take off the sleeve and do some poking about thanks guys.

Try it with the filter off. See if that makes a difference. When it's right, you'll know it... I whine to myself at the sq footage I loose. Have thought about adding some pvc bracing to keep it all open.
Better to be overpowered and reduce than always running at 100%...

Also, I take it since were dealing with lights on / off, your running photos? If your running autos, go to lights on 24/7 for the last couple weeks.

 

[Son of Hobbes]

Thanks guys oh believe me first thing I checked was the direction of airflow well a certain amount of air would get into the attic through the eves and I also have the little flap open at the top of window in room where the tent is set up which is a small box room. Have specs of fan below im sure there is enough power for the size of tent with short ducting that only has one bend.

I do have a attachment on the end of ducting to direct the air flow into the eves of attic im not sure if this could disrupt the flow of air?

I also have a sleeve on the carbon filter which is a 4 inch Rhino Pro could this sleeve being a little dirty disrupt the airflow?

Doubtful that it's so clogged it's preventing airflow; and doesn't explain the positive pressure. You should wash the pre-filters between grows though, and ALWAYS run the scrubber with the filter on; the filter catches all the large particles (like dirt, smoke etc) so it doesn't clog up on the carbon inside (which is meant for much smaller molecules.)

 

[StevOrganic]

Doubtful that it's so clogged it's preventing airflow; and doesn't explain the positive pressure. You should wash the pre-filters between grows though, and ALWAYS run the scrubber with the filter on; the filter catches all the large particles (like dirt, smoke etc) so it doesn't clog up on the carbon inside (which is meant for much smaller molecules.)

I will do some serious investigation this evening as I have only 2-3 weeks left until harvest flowers are packing on size and dont want to mess it up now thanks for all the great advice guys.

 

[Simplicio]

If tent walls are bulging out, then the pressure inside the tent must be greater than the pressure outside your tent, assuming the fan is working.
The only other explanation is that the fan is hooked up backward.

The attic is directly connected to the tent, so the real question is why is the attic pressure so high?
Conceivably something else in your house, or external conditions, is venting into the attic to increase pressure there.

In general wind blowing across attic vents will reduce pressure inside the attic due to the venturi effect, so this is mystifying.

 

[StevOrganic]

If tent walls are bulging out, then the pressure inside the tent must be greater than the pressure outside your tent, assuming the fan is working.
The only other explanation is that the fan is hooked up backward.

The attic is directly connected to the tent, so the real question is why is the attic pressure so high?
Conceivably something else in your house, or external conditions, is venting into the attic to increase pressure there.

In general wind blowing across attic vents will reduce pressure inside the attic due to the venturi effect, so this is mystifying.

You are spot on man I'm a complete and utter dodo it was backwards I must have put back the wrong way after cleaning a while back sorry for wasting everyone's time and thanks for helping me realise my silly error..

I'm lucky to have caught it going into my last couple weeks flower and this is why this site is so great people are so nice that nobody just came out and said you silly idiot its backwards everyone was trying to find other reasons this was happening.

Also could this have negatively effected the growth of plants? They look perfectly fine to me with 2-3 weeks left

 

[derek420colorado]

You are spot on man I'm a complete and utter dodo it was backwards I mist have put back the wrong way after cleaning a while back sorry for wasting everyone's time and thanks for helping me realise my silly error..

Lmao all good my friend glad you got it all sorted out.