I have the innovative marine micro 30. You want your water level so that the water is running into the middle chamber...
On the first picture you can see my chambers in the back. You can see my filtration at either end. Then the skimmer chamber (don't have one) and then the heater chamber where you can see the heater.
On the second picture you can see the middle chamber where the pump is. You want you water flowing into the middle chamber. So you want the middle chamber water lower then the rest.
You can achieve this by removing water if you have too much.
Note: my water is only just lower in the middle chamber (like half an inch) because I just topped it up.