4 inch fan and filter will be a better combo for a 2x4 tent and will still need to be reduced in speed actually. also im sure some of the noise is simply because u dont have the filter attached to the fan right now so ur hearing open wind rush but im willing to bet alot of the noise youre hearing probly isnt the fan itself- its the speed controller that im guessing you use
View attachment 4555785 look like that? these type of speed controllers suck, they actually function not by slowing your fan speed but by constantly switching the fan on/off so that it never gets up to full speed, the downfall is though that switching the fan on/off constantly like it does will burn out fans in a heartbeat, and also produces that annoying hum that youre undoubtedly hearing. switch to a true variac controller like this
View attachment 4555787 lil more expensive that the cheapos (ususllay around 60-70$) but well worth it as you wont be hearing your fan anymore. i sleep next to my tent and the loudest part of my whole setup is the light waterfall sound of my reservoir circulating through the chiller, which actually helps me sleep lol.. but i cant hear no fans whatsoever. these types of controllers work by reducing the constant voltage being sent to the fan, which actually reduces the speed properly, and is silent!!
and yes with a 4inch fan and filter properly dialed in you wont have any smell on the exhaust end, always keep in mind that the room your grow is in will always smell, whats important is keeping the smell from escaping which is what carbon filters do for us. if your worried about the smell in your grow room then what you could do isuse the 6inch fan filter u have and set it up in a corner of the room so that the air staying in the room is also being scrubbed, not just the air being exhausted.
i have dyna-gro's full line personally but all you will really need for a simple start to finish grow is the foliage pro, you could also pick up a small thing of pro-tekt which is their silica solution, just helps plants be a little hardier and put up with temp swings and stress's easier, and you could also pick up a small thing of bloom if you wanted- the foliage-pro is good enough to use as a flowering feed by itself but when properly mixed with bloom it essentially functions as foliage-pro+pk booster, but neither of those are 100% necessary if you dont want to.
To clarify i do not use all of dyna-gros line in my res all the time, only pro-tekt, foliage-pro, and bloom regularly, i have their mag-pro product that i use when i need a mag boost but that isnt too often, i run their enzyme product usually once every other month or so to help keep things clean, i also use a mixture of the foliage-pro and their specialty bonsai-feed for my mini-mothers, i also have the K-L-N rooting product, and neem oil also. im just a big fan of their line, PH stable, good NPK ratios, and even when i "forget" to flush a plant before harvest (which i have to do manually since my res feeds a perpetual grow no 2 plants are ever the same age) i never get a chemical aftertaste, leaves pure white ash behind, so yea its just been good to me.