Ventilation and Lowering Humidity Question

How's it guys and gals. So I have a question, I am living in a costal area and my humidity is rough is usually 55-65%, and 70% at its peak. Currently I am running a 400 W HPS in a cooltube, with a 440 CFM exhaust fan. My grow area is a 4 foot x 4foot x 6 foot grow tent. I have attached a diagram of my proposed idea to lower my humidity %. Currently I am just sucking the hot air from my room through my cool tube's open exhaust. But I was wondering if I added another ducting exhausting from the top vent hole, and run it to a Y- duct adapter, if that would help lower my grow tent's humidity levels. Any input would be greatly appreciated!

first you should only have one duct hooked up to the fan.

also you should attach a carbon filter to the other side of the cooltube and hang it above the light.

then have an intake on top and on bottom if possible pulling air in from the outside.

i live in a coastal area where my summers are similar or worse! but in the winter it gets real dry

good luck!

You could run a dehumidifier in the room the tent is in so that it is pulling in dryer air.