Can someone explain these charts!!

Here's a chart measuring temps, EC and water content. I get what it's saying but how is he so dialed in and what's are the benefits to letting EC fall so sharply. This is a instrgram chart and the guy has some extremely good stuff. Just curious if someone could break this down for me.

Much love thanks

Sandiegogrow said:

what's are the benefits to letting EC fall so sharply

Click to expand...

He added water right when the EC dropped sharply.

churchhaze said:

He added water right when the EC dropped sharply.

Click to expand...

Is he flushing to get rid of salt build up?