For small aquariums, a stable osmotic balance is important, because they are particularly sensitive to constantly changing salt concentrations. The Tunze Osmolator Nano 3152 which was specifically designed for this, is a water level controller with only a single sensor and is equipped with a processor-based controller that protects against overfilling. It is suitable for nano aquariums or small aquariums up to 200 liters (55 USgal.).