Pupose

My pond has two parts:

1. A normal pond for plants and a few goldfish.
2. A natural filter, gravel, sand and plants to filter out any nutrients and poo produced by the goldfish.

For a good filter the plants need a regular supply of nutrient rich water. So a small pump is added to the pond to pump the water in the filter. For a good filter function the pump as to stop working to let the plants in the filter absorb the nutrients, stop working when it's to warm: the water will vaporize and stop working when the air or surface temperature is below 0 Celcius. Also, to keep the fish alive a airpump will supply the fish with oxygen in winter and when it is very hot (above 30 C). In the picture you see the pond when constructing it. The red gravel is the filter.

This is an excellent job for the Arduino board, pump and air will switch 220VAC and three AD ports will be used to sense the temperature.

• At the surface of the pond.
• One meter in the air.
• In the filter.

A waterlevel sensor will be used for to stop pumping if the level drops to low.
The whole program needs to be fuzzy and datacollecting just for fun and usage of the USB / Serial port.