RH during flowering too high

I've searched for a dozen combination of RH, High Humidity, etc and can't seem to find what I'm looking for.

I need to lower the RH in my 4x4x6.5 grow tent.

I recently repotted 5 WW females into their 3 gal pots with a soil mix This is after them being in 12/12 under a 400w HPS for a week in smaller pots. The 5 girls showed their sex so I repotted them in 3 gals, watered them well, changed the light to a 600w HPS and expected to see them go crazy. Well they aren't looking too bad, but the humidity in my tent is way too high. between 65 and 75 since the minute I put those plants all in the tent. I guess the moisture in all that new soil is too much.

There's a rotating fan blowing on them and a carbon scrubber fan sucking and recircing air in the tent. I have not put up ducting and another fan on the light hood yet, mainly because I haven't had time in the last couple days, but my temps are fine (60 - 80, night - day) it's just too humid in there.

What methods do you use to lower the RH in a tent? Is the only thing to buy a small dehumidifier? They look like a couple hundred bucks at amazon and would like to find a less expensive way, if possible.

I'm worried they will mold, even though they're early in the flowering stage.

How do you guys lower your RH in a tent?

Thanks

just a quick bump...

ventilation

keep the door open on the tent and maybe add some supp co2

Thanks, guys. Appreciate the feedback.

One more thing... Is 50% the RH percentage I need to keep it below during flowering phase?

50-55% is optimal for flower i believe, obvi lower is better so aim for 50%, go to walmart u can get a small cheap dehumidifier there..if thats not an option, get another fan in that tent blowing more air around, (more air circulation=less humidity)