What ppm am I aiming for with each EI dose?

I'm trying to understand my tank and the dosing I'm giving it. I know that exact levels aren't critical and that is the basic aim of EI dosing - maintaining levels at or comfortably above what the plants need. Trouble is I'm a scientist (physicist to be precise) and I just love to test and tweak so that I can observe what's going on. I have one fundamental uncertainty:

I see 'recommended' levels of each nutrient as the bands in which 'plants do best' (figures such as 10-20ppm for NO3, 0.5-2.0ppm for PO4 and so on). Am I aiming to dose to these levels as a total for the week, or am I aiming to maintain these sorts of levels for the 'majority' of the time?

Lots of quotes in the above question to indicate that I realise that these are ill defined words or phrases BTW.

Peter

PS: My plants are starting to look better already, thanks to your help and EI style dosing with dry ferts. My thanks to you all for your help so far.

 

Just as well I only quoted figures to one significant digit then ;-)

I'll just carry on dosing towards maintaining those 'recommended' figures and taking my own observations of tank uptake to tune the quantities added.

Peter