WaterRower recommends using clear water to fill the tank of your rowing machine, preferably (low-limescale) water straight from the tap. Even if the water is very clean, limescale and algae deposits can build up in the tank over time, especially if you do not use your rowing machine for a long time and the water is left in the tank. To prevent this, add a Puritabs care tablet to the WaterRower tank every two to three months. It prevents the formation of such deposits. Please only note that you should not use the Puritabs care tablets together with blue water paint - the chlorine contained in it dissolves the paint.