tank cleaning

Question
i have a 75 gal tank and was wondering how often should i change the water and clean the tank.

Answer
Depends how dirty it gets how quickly :)

On my 55 gallon i have a fully planted tank so it's pretty self maintaining. I would suggest doing a 35% water change weekly. Cleaning the tank glass is up to you entirely. Getting a test kit for the tank will help you seeing if your water quality is suffering meaning you should do more water changes..