DarkDevil LED COCO

hey guys
New grow will be starting here soon with a completely new setup. First grow I did was nirvana ice a while ago. Turned out pretty good and I got maybe 2oz between 2 plants. Hoping for better results this time. Equipment will be dribbling in this weekend and beans are on the way right now as well.
Will be setting everything up and testing everything beginning of the week, hopefully Monday. Looking for any feedback on my setup or advice. This will be my second grow and first time using Coco. I'll probably run 4 plants probably 2 of the dark devil and one of each of the others.

Strains will be
-Sweet seeds Dark Devil!
-Fast buds Girl Scout Cookies
-Fast buds Pineapple Express
All strains will be autoflowers

Setup with be a 36x36x72
Ventech 4inch fan and carbon filter
Mars2 900w LED
Grow medium will be 100% coco using h&g coco nutes and roots Excelurator.
5 gallon smartpots

Got my new stuff in this weekend and set it up for a test run. I'm having heat issues. Temp inside the tent is set at 88-90 degrees. Any ideas on how to lower it?
The fan is a 4" ventech unit pulling through the carbon filter. I have a small circulating fan inside but I think I need one a bit bigger.