Hi,
First off, I am an Arduino newbie.
The goal of my project is to measure how much liquid has been contained in a large bottle over the course of the day, as it is being constantly drained and refilled.
My first step has been to buy the 8" eTape Liquid Level Sensor to at least know the water level at any given time. I can get a reading but it is not that accurate. My next step will be to try to program the Arduino so that it records the water level dropping, adds the value to a total that keeps aggregating. This way, as the water level lowers and rises throughout the day, my program will have added up the total differences, giving me a total in liters that has been drained from the bottle.
I am wondering if anyone has experience with this sensor. If so I would love to get in touch and discuss a few things.
Furthermore, if anyone has the arduino experience to be able to program what I am imagining, and is interested in a contract job to help me with the programming, I am open to getting professional help. (I never thought that I would say that in a web forum) 
Or if you cannot, do you know who I can contact to ask about this here in Montreal.
Thank you in advance for your help.
-Charles.
Hi Charles,
This sounds like a pretty interesting application. Is it possible for your bottle to be filling at the same time it’s emptying? If so, I’m not sure your proposed solution would work since it wouldn’t notice a change of liquid level. Perhaps you might want something like a Water Flow Sensor?
If the bottle only ever fills or empties, then this sensor should be easy to use. We don’t currently have it in our catalogue, but we can special order it for you. In addition to the 8" model, we can also order the 12" model, if you wish.
I think the general design of the Arduino program would be regularly sample the resistor’s value using a voltage divider setup and calculate the liquid level. If the level has increased since the last sample, add the delta to your counter. If the level has decreased since the last sample, don’t modify your counter just adjust your reference value.
This method calculates the total liquid added to the bottle, which would be the liquid in the bottle plus the liquid that was drained from the bottle. A similar algorithm can be made to calculate other values.
Question: what do you want to do with the counter value? Do you want it to be displayed on an LCD screen? Or would you like the value to be stored on an SD (using an Arduino shield) so that it can be used with a computer? Most of the Arduino’s memory is volatile, so the counter value will be lost if the power is removed.
Hope this helps,
Or if you cannot, do you know who I can contact to ask about this here in Montreal.