How to make your own Rainwater Tank Level Indicator

This video shows a simple visual water level indication system which can be made and installed in about 20 minutes using parts from your garage.
In this video, two 1000 litre slimline tanks from two different manufacturers are each fitted with such water level indicator.
The Western Cape region of South Africa is currently experiencing a severe drought, causing people everywhere to be installing rain water tanks. Something which is not so easy to determine, is the exact water level of a tank. Knocking the tank or feeling where it gets colder are not very reliable methods.
The principle utilises a floatation device inside the tank connected to a weight, acting as an indicator, on the outside. To prevent the weight from being blow around in the wind, it will have to be stabilised and guided along an optional scale along its path of travel. The tank’s water level can thus be determined at a glance. The timelapse shows me busy straightening a desired length of wire, which will become such a guide.
Sorry for the sound track, I suffered badly from hay fever at the time.