Howdy Happy,

I did some lookng at one of the hydroponics places online,and the closest I could find to growing in a tube method,is the aeroponic set-ups..is that what you're talking about ? If so,you may have trouble finding a retail unit,that will fit into your 18 inch width,however..you may be able to construct your own unit,that will fit in the space that you have..or git someone to help ya.

I was hoping that some of the hydro guys here,would help you more..but if they don't,you should pose this question at Overgrow and at Cannabis World,or Treatingyourself..there should be folks there,that can help you.

I want to try the DWC method(deep water culture),myself,but in order for it to work well for me,I'll have to buy a somewhat expensive ,pump,to change out the solution..so that I won't have to lug around heavy buckets of water.

I'm rootin for ya man ! If you succeed-I succeed too..we're both in need of a low-stress way to grow our own medicine,and trying to find the strain that suits our needs.

Have a good one !