How to reduce humidity in my tent?

I want to reduce the humidity in my grow tent. Currently my controller cycles frequently to suck out the humidity which quickly goes back up. This is wasting my CO2 that i inject. I'm thinking about doing some sort of panda film over the top of my tray/pot. Possibly cutting a hole for each pot and taping that to the tray sides, then making a disk to cover the top of the pot. I use 50/50 mix of perlite/coco and I threw some extra coco down around the pots when I saw roots starting to poke out. I'm watering for 1 minute a day from 1/4 lines to each pot.

Since I'm using Co2 I'm letting the humidity go up to 80 before turning the fan on, but it gets there quicker than I would like. I know I could use a dehumidifier, but I'd like to keep from buying another piece of equipment for this 4x4 tent.

try watering less....more water=more humidity...with that mix you can go without water for longer then 24 hours...just check the medium....if its damp 2 inches down then it DOESNT need water....that is your second best option other then what you already said.

If its cold outside the box, humidity will rise inside the box..... if temps stay even in whole room humidity wont rise... as much

thats my logic