Terrarium humidity

[kentosaurs]

Hi everyone

Okays i recently got a hygrometer ( a cheap one ) from a pet shop in Ikano......And so i placed it in my terrarium for highland neps and i realised that humidity is very constant but i can't seem to get the humidity higher at night.Almost 90% of the time humidity is around 70+ and normally after i water my neps or mist them they only go to 80-84%........It never gets lower than 70% in the terrarium which is good but somehow i can't raise the humidity at night....I already have a box cover with water inside the terrarium and i'm not sure if that even raises humidity but i hope it does.....For now i don't intend to buy a humidifier or stuff like that cos it cost to much.Anyone has made they're terrariums having higher humidity at night without special gadjets????????????

Ken