Ive been doing some temperature research.

I have a 10 1/2 in exhaust fan on the lowest settng placed inside a 5 gallon for coolng.

Theres a 8in intake fan.

Now i leave the intake on only till 77.0 temp is reached then turn on the exhaust wth intake and the temp seems to mantain a constant 77.0

I was comparing environmental controllers for this purpose but I found that the controllers on the market in the usa dont have a variable fan speed to control idle speeds to maintain temperatures. They only switch them on and off once certain temperatures are reached.
Unless someone out there knows of one.

I have found two that are made over seas, primair and theres 1 on ebay noname but they monitor the rooms temps and adjust as needed.

settings to cool or heat and maintain as needed