@Jamminbear the nutrients are indeed triggered by the fill which is done post-drain.
If you sit and wait about 2 min after the fill is complete you will hear the pump going and then bottle 3 doses, then a couple min later bottle 4, then a couple more min it’s bottle 5.
In my experience (and in talking to Grobo peeps) there is no need to do the drain/fill immediately when the notification comes in. I’ve always had to do it the next day or even the day after with no issues.
It’s not always convenient on a Thursday at midnight (when my notification is )