Tunze Nano ReefPack 200 water level problem

[Freo]

I'm using a Tunze Nano Reefpack 200 and I'm having trouble maintaining the correct water level. There's only about a 5mm tolerance and the problem is a result of evaporation during the course of the day.
If the level is too high the surface water doesn't get drawn into the filter, leaving a layer of protein on the surface that doesn't move.
If the level is too low air is drawn into the filter pump, blowing bubbles across the tank and making the pump noisy.
Is it possible to fit pipes to the unit so that when the level drops low, water is drawn in from below surface level until the tank is topped up?

 

[rvitko]

The best solution is to add a top off system or top off more regularly. It is fairly sensitive but the water level fluctuation is also stressful to the inhabitants and this is another reson to try to maintain it within the window of operation. You could open the filter and turn down the pump, this may help.