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how often system check the water level and activate the connected pump (one time per 60 minutes is better for accuracy than one time per 10 minminutes)
how long is the pipe from the pump to your sump (shorter pipe better accuracy, we need to understand that pipe in this case after added water is always empty) - during calibration you have the amount of water in the 30s it 30 seconds. It means that the result is for 30s 30 seconds working pump included the start of the pump (time from start to work) and amount of water in the pipe. The best for accuracy is to have a similar situation - the pump will work for the 30s30 seconds.
accuracy of your pump
if the pump has a soft start
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