Hi Minc,
Yes, i using on water reservoir with low movement, basically a flat surface. To use on liquid with some waves, you can use a solution propose by original instrutables, putting the sensor inside a pvc tube, who have both ends open, measuring the average liquid without waves.
The code is good for 1 measure per sec, but can be optimized to 10 per second easily, and increase the precision by using average. In this case, use a Local blynk server, to avoid flooding and get blocked.