The Observant C3 and Solo Tank Level solution uses the Senix ToughSonic Ultrasonic Sensor. This sensor transmits ultrasonic pulses that reflect off the water surface back to the sensor. The time between transmit and receive is used to calculate the distance.
With this in mind, there are are some installation and operation considerations to be taken when resolving inaccuracies in tank level readings.
Water Level Readings have spikes or noise
Spikes and 'noise' in tank level readings (as below) may be induced by 'echoes'.
This can be caused by the sensor being installed too close to the side of the tank.
The sensor should be a minimum distance of 15% of the "tank height" (see above) away from the edge.
This can also be caused if the sensor is not pointing directly at the water surface at a clean 90º angle. If this is the case the ultrasonic signal can end up bouncing a number of times around the tank before returning to the sensor and therefore creating inaccurate readings. Ensure the sensor is pointing straight down.
Also note that for the temperature compensation to work correctly the body of the sensor needs to match the ambient temp as close as it can, so it's important that it's shrouded from direct sunlight.
Water Level Readings are consistently inaccurate
To calculate the water level, Global uses the distance to the water surface measured by the sensor in conjunction with the measurements of the tank provided.
If tank level readings are consistently inaccurate then it's likely the measurements provided are not correct. This often results in reported water levels greater than 100% or reported water levels that never reach 100%, even when the tank is full.
To revise your tank measurements, see the Managing Tank Level Settings article.
Sensor Reports 'Under-Range'
See Senix Level Sensor - Under-range error for details.
Tank is empty but Water Level Readings are not 0%
Firstly, ensure that your tank measurements are correct and see the Managing Tank Level Settings article.
Some other possible causes are :
- The distance between the bottom of the tank and the sensor is beyond the maximum distance of the sensor. The most commonly used version of the Senix ToughSonic has a maximum range of 4m.
- If the sensor is installed above a dam then the floor of the dam may not be a flat surface when it is dry. This results in the ultrasonic pulse being scattered and not returning to the sensor.
In both the above cases, the reported readings may be close to 100% or in some circumstances the sensor may report 'Under-Range' (as above).
Tank is full or overflowing but Water Level Readings are 65-85%
This observation suggests the sensor is fully or partially submerged. It is further characterised by a sudden drop, with high tank readings either side of the incorrect readings (as below).
The Senix ToughSonic will continue working when submerged, however due to the speed of sound being 4x faster in water, it reports a distance 1/4 of the full depth of the tank. This results in a reported water depth of 3/4 of the full tank ie. about 75%.
If you have further questions about Water Level Readings, feel free to send your inquiry to the HelpDesk