I rent apartments just to grow in, legally and illegally. 6" filter with inline is what i use and ive never had a problem. You have to have a credit card or friend with one you can use in case you have to rent a truck to hide it. Legal or not, you could still be robbed and your landlord will probably think it will destroy his property. You can't exactly run away from an apartment either, so i take security in them very seriously. I black out a bedroom and exhaust out the window. I put a black sock over the end to hide the metal and a houseplant on the balcony to further hide it. I put an ona block on the houseplant medium and aim the exhaust at it. I put an ona block at the entrance also, you have to keep them away from buds or they can attach to them and ruin their smell and taste. I also lock the bedroom door and keep a camera on the entrance to both. If the landlord ever needs to get in, i just put everything into a truck until they're gone. Some buildings are really hot so you need a high/low hygrometer for when you're gone. I always try to get the top floor, but that's not always available. I refuse ground floor apartments for this though.