Trying to parse this out. There are a few questions regarding the data:

* Your first set of equations is looking for a start of 2015-03-12 06:00 and an end of 2015-03-13 06:00. For the start, there are two identical cells right at the top. For the end, there are also two cells though they are not consecutive (B68 and B51).

* The measurement intervals seem to vary widely, any where from 15 to 480 minutes. Is that right?

* Lastly, there seem to be quite a few duplicates.

At any rate, I guess the problem with the third is that the zero data are some kind of mistake or something like that, correct? So, in that case, you want it to use the previous data of 8.8. Is that right?