I have a dozen or so 4 liter empty plastic water bottles. I would like to begin dabbling with hydroponics by using them. I would like to plant tomatoes, strawberries and maybe cucumbers (4 of each). I think they have similar requirements in terms of nutrients in the water, ph, etc. Can someone recommend a particular system to set up using them? I would like it to be a central system rather than attending to each pot individually so that I have the experience of maintaining a water pump, air pump, etc. Any ideas?