dude.. let me start by clarifying that I am a complete lazy ass.
unfortunately, my girls are like, errr.. 3rd down on my list of priorities, which is why they suffered so much this past round. 1] school, 2] not getting caught 3] getting laid/ gardening 4] gardening/getting laid.. something like that.
It depends on whats going on.
-Flushing out and cleaning the reservoirs is what takes the most time, aside from construction of your RDWC system itself. I do this every 2-3 weeks (should do it once a week), and it takes about 5 hours for my flower system, and 5-6 hours for my veg totes. This is mostly because of the speed of my RO system (200gpd) which is slow. Takes 35-40 minutes to fill a 5gal jug.
-Adding nutes takes about an hour when needed. I try to check them once a day, and when they are really doing well, I need to add nutes every other day or so.
In conclusion, I spend about 10 hours a week maintaining my indoor garden when everything is working as it should.
The absolute BEST thing about RDWC dude.. the best.. is that I can leave my plants for up to a week at a time. During this time they might get low on nutes, but they recover very quickly in DWC. So if you want a garden that you can leave for days, RDWC is perfect man.