Farmbot liquid level sensors (water, diesel, liquid fertiliser) use pressure to measure the amount of liquid level above it. At Farmbot, we know that each water point and set-up can be slightly different from the next.

For example, what if your probe isn't sitting at the very bottom of your tank or reservoir?

'Offset height' is a simple way to adjust the height to reflect these differences.

Below we use a couple of examples to illustrate when it can be beneficial.

Imagine you have a 200 cm tall tank that has a 20 cm layer of thick mud or soot at the bottom. The water level probe sits on top of that and, therefore, is 20 cm from the bottom of the tank.

When the water level probe detects 100 cm of water above it, it will show a reading of 100 / 200 cm (50%). However, this may mislead you to think there is 50% capacity left in this tank when the bottom 20 cm is mud/dirt.

By adjusting the offset (add 20 cm), the water level will show 120 / 200 cm in your tank and read 60% capacity. Therefore, you know there is only 80 cm or 40% available space in that tank.

On the other hand, imagine you have a 200 cm tall tank with an outflow pipe that sits about halfway up the tank. Your water level would never go below the outflow pipe, and the tank would never drop below 50% capacity.

Therefore, when the water level reading is 50% full, the tank is essentially empty as water will no longer flow out of the pipe.

By adjusting the offset (subtract 100 cm), we update the 'true bottom' to the 100 cm mark on the tank. Now, when the tank has 100 cm of water, it will show as 0%. Now just with a glance at MyFarmbot, you can see how much water is really available in your tank.

If you have any further questions, please contact Support on 02 9901 4798 or services@farmbot.com.au.