Green cloudiness is usually an algal bloom - microscopic algae floating in the water. This can occur if any of three things are out of balance - light, fertiliser and carbon dioxide.
How long are the lights on for?
Do you have any live plants in the tank? And if you do, do you add any fertiliser and carbon dioxide, either gas or liquid CO2?
Does sunlight shine directly onto the tank at any time during the day?
The first thing to do is work out what is causing the algae, then change something so it doesn't come back after you've got rid of it.
Then to get rid of the algae you need to cover the entire tank with something that won't let any light at all through. Turn the tank lights off, and leave the wrapping in place for 3 days. Don't even open it to feed the fish, they'll be fine for 3 days without food.
Three days without light usually kills the microscopic algae. But it will come back if you don't sort out what caused it and change whatever it is that caused it.
The white pad on top of the filter should help remove any ordinary cloudiness, especially if you change it regularly. It gets clogged easily and doesn't wash well. It is much cheaper to buy a length of filter wool/filter floss from a roll and cut it up using a Juwel white pad as a template.
