Wasserpest - though I've already got my autodosing set up, I think it is great that you are actually working out an economical alternative!
I hope you are going to keep posting your progress, for if so, and if this proves successful long term we might see a lot more autodosing. And if that is the case, I really look forward to dialogs about autodosing protocols and regimens. For instance:
1) Is it better to auto-dose with a level target? This implies that after each water change you have to perform a "gap dose" for the new water.
2) Do you dose micros on the same day as micros? And if so, do you dose them daily (obviously in smaller doses)?
3) Do you do periodic testing to understand your plants uptake rates set your auto dosing levels accordingly? Or do you do adopt something closer to an "autodose EI", with target assumptions and allowing water changes to keep this from getting to out of line?
These are just a few of the questions that I've had to decide my own answers to over the last year or so of autodosing. I welcome the possibility of a larger group of autodosing members so we can begin to hash some of this out.
Please keep up the good work. And please keep us informed of your long term progress!