HELP! Air flow with a 6” to 4” reducer

[mmxk]

For this grow, I decided to add 400W of LED to my main 220W LED grow light to increase my yield in a 3’ by 3’ tent in a hydro setup. I’m starting week 4 of flower and so far, I was able to maintain an acceptable temperature of about 76-79F in my tent with a 4” inline fan at 80% setting but I had to uncouple my carbon filter to increase the inline fan air flow. With a brand new and clean carbon filter attached to my 4” inline fan and with a 4” booster fan farther in the duct, my temperature jumped to 80-83F and I’m having a hard time to drop my humidity below 50RH. I have a full size dehumidifier (about 50-60 pints) running on hi setting during the day which increase my tent temperature but the humidifier exhaust is ducted outside the tent with another carbon filter at the end.

I’m thinking of purchasing a new 6” inline fan and 6” carbon filter but the ducting I’m using to blow the air outside of my house 4” and I can’t increase it to 6”. I’m thinking of using my 4” booster fan right after the 6” to 4” reducer. Would the reducer nullify the benefits of using a 6” inline fan?

6” carbon filter -> 6” duct -> 6” inline fan -> 6” duct -> 6” to 4” reducer -> 4” booster fan -> 4” duct -> outside

[oldjarhead100]

the difference between 4 inch and 6 inch is the volume of air being pushed or pulled a 4 inch fan moves air much slower than a 6 inch so with a 6 inch fan you should see stronger air flow , I have a dehumidifier in my bloom room as well but I dont duct the exhaust out it is the dehumidified air , I let mine run and eventually it will shut down when it reaches the set humidity ,then it shouldn't affect the heat so much
Ducting systems need to be a straight as possible for every 90 degree turn you will be adding feet of ducting the air has to go though, if your grow area is in the house can you ran an ac unit in the room

[Toker1]

Never reduce to lower diameter. You will choke your air flow. IMO, the cheap LED lights you are using are the issue. Too much heat and not many lumens coming from the blurple color light types. Sorry to say.