Max from calcul

Hello,

I have calculated a number device down on specific date and time

I have a Event table with down and up events and a Node table (with actual down). And another calendar and time table.

I calculate : Actual down - sommeeventdown + somme event up

If I use a graphic, no problem, I have number by day and time. 

But, I would like, for example select 29/07 and know haw many device is down. With a card I have a number but I would like to have a max value (104)

How can I have a max from a calculate (my values are calculated and not are in column) ? Or get value according to the date ?

Here an example :

Thanks for your help