Indoor ADVICE ON CFM AND EXHAUST. PLZ help

[Julian]

I Have a 440cfm 6" inline fan + 6 inch Carbon Filter for my 4 x 4 x 7 Grow tent. I have only been using my 450w LED, so the temp has not been high enough to run my inline fan. Today I turned on my 400w MH , so I decided to turn my inline fan on. It comes with a speed controller , so I had 440cfm set on the lowest speed.

Temp Before Turning on MH and INLINE FAN: 80-82F
HUMIDITY Before Turning on MH and INLINE FAN: 75%

After turning on THE MH AND INLINE FAN the temps rose to 87f , while the humidity dropped down all the way to 38%
I have a TaoTronics auto Humidifier, so that my Humidity constantly stays at 75% , so buying a humidifier is not the solution.

Basically Im wondering If I can plug my inline fan that already has a variable speed controller , into another speed controller.
The inline fan I have now just seems to be too powerful for my tent , and I can't downgrade to the 4" Inline fans because almost all 4" inline fans have a cfm lower than 230cfm

Any recomendations?

 

[AutoWonders]

Have a 440cfm 6" inline fan + 6 inch Carbon Filter for my 4 x 4 x 7 Grow tent

Double checking that your filter cfm is larger than the inline fan cfm and that the fan is going the correct direction.
I don't like the 3 speed controllers. I have a couple of Variac controllers. I rarely go past 50%. Control with the Variac is highly incremental....
www.amazon.com/Electronix-Express-Variac-Variable-Transformer/dp/B006NGI8VS/ref=sr_1_1?ie=UTF8&qid=1518914340&sr=8-1&keywords=variac+controller