Not the same level you started with due to some the plant used and some they did not use as well as what they put back them self.

So that does not mean that your plants did not use any nutrients but I would check the Ph and make sure it's right. The wrong Ph can make some nutrients unavailable to the plant even though there in your water the Ph keeps the plant from absorbing them at that time.

After 5 days and 40L anywhere from high 800 to high 1100 would be normal for that period. But that does depend on how old they are and what cycle of life they are in too, temperature ect. If the temp is cool they may not drink as much as if the temp was warmer too.

Hope that was some help.