Smell seeping out - Need better fan?

[TorturedSoul]

I think I misinterpreted what you meant, I thought you meant if they were being sucked in too much that was a bad thing.

<SHRUGS> I would consider it so. One lights the total grow space (or should). If one then allows negative pressure to decrease that space, one is losing part of their growing space.

Man if I never bought a UPS to protect my hundreds of gigabytes of porn I ain't going to do it to keep my neighbors from smelling my flowers

Yeah, but if your neighbors knew about your stereotypical "50-year old single man in Mom's basement" computer pornography collection, they'd (mostly) just think you were some kind of pervert, lol.

But even with your mastrabutory aids, you probably haven't set up a 72" monitor displaying porn 24/7 on your sidewalk out front :rolleyes3 - and a cannabis grow that doesn't have proper odor control sort of does the olfactory equivalent.

But it's different when you're legal, my main reason for wanting a filter is that some people are just nosy and complain about the smell, and you don't necessarily want to make yourself a target for robbery either.

True - but I am not knowledgeable about the OP's legal situation. And some people - and some landlords - might get bent out of shape, regardless. Even if letting an odor escape did not provoke legal - or housing - difficulties, there is no harm in being a good neighbor (in the sense that good fences make good neighbors, lol, and one of the things that a fence does is keep your... things off of your neighbor's property - something that I am reminded about whenever the guy across the street has a cookout, because he apparently is unable to understand that one does NOT need an entire container of naptha to light charcoal...). And, as you say, there is no reason to make things easier for thieves who are wandering around looking for a home which is likely to have things they could steal - or to cause one of your neighbors to get mad and put an ten-foot wide sign in their front yard stating "Robbers: If you are looking for the indoor grow operation, you have me confused with ===> THAT ===> neighbor! Please do not break into the wrong house by mistake!" :lol:

Good idea to prevent light disruption though!

A UPS? True, but I was talking about one for the exhaust fan. I would assume that it isn't tied in to the light. If it is, that could explain how the smell gets into the wrong area for the OP, if he shuts his exhaust fan off every day, I suppose...

I don't think enough people take this into account when putting a grow tent together.

I heard it said once that if one does not understand the importance of good odor control, sooner or later a nice man (or woman) in a uniform will come explain it to them, lol.

I neither agree nor disagree with the 3X air exchanges per minute

It's just a general rule. People go with less (either knowingly or by expecting a cheap fan to move its rated capacity of air through a carbon filter and/or a long convoluted duct run (often reduced in size) instead of the 40%-60% that it is probably managing, lol). Like most general rules, that one undoubtedly takes into account less than stellar setups - such as using a light that is not connected to its own separate duct setup to remove its heat from the grow room without allowing the bulk of it to "contaminate" the rest of the grow... And the link in the OP's .SIG does state "...Under LEDs." AfaIK, there are, sadly, only one or two LED companies that offer products with good, sensible 6" or 8" round duct-adapters for such purposes. So I assumed that the OP's exhaust fan had to serve double duty (and the same for his carbon filter) of dealing with both the grow room (tent) AND the light(s).

It seems to me that the negative pressure is more important than how negative the pressure is.

That's my thinking - if you are meaning strictly in regards to odor control, anyway. Visual signs of negative pressure indicate that, even if there is a hole in the tent, the airflow must be into the tent.

I have found it gets hard to avoid low humidity with the fan at max output as well.

That depends on the ambient conditions of the environment, the type of growing method, even things like number and size of the plants, methinks. If, for example, you are running a small number of LARGE plants in separate DWC reservoirs, each reservoir is large enough to bathe a small child in, you keep the levels of DO (dissolved oxygen) in those reservoir high enough that it'd take a mouse half an hour to drown in one ( ), and your temperatures are fairly high... The plants are probably humidifying the grow through their natural evaporative cooling (transpiration) ability. Small plants with small root systems in small containers full of soil will not be able to transpire as much moisture, and certainly aren't likely to transpire the 10+ gallons/day that a large plant could on a hot windy day.

Just another example of why a grow room that has been designed as a complete package (including the plants that are to be grown inside it) tends to be more successful than one in which the person putting it together did not think about all the various components as being merely parts of the whole.

But, yes, humidity control is important too. A cannabis grow is a balancing act....