I buy sap from a couple of people and I've always gauged the amount of sap in a collection bin and used that as the amount that I'm collecting and paying them at the end of the season. Is there a more precise way to know how much I am collecting such as a flow meter with a sum of what was collected? I know there are ones for fuel but what about a food grade option? Any thoughts? I thought about a stick to measure the level of sap but they all have different bins so that's why I'm wondering about something more precise that measure the exact amount I'm pumping.