I used polyethylene tubing of various sizes for conduit.  You can get it at Home Depot, for one, and its very inexpensive.  Its white in color and translucent.   To attach it, you can put 1BID strips over it at 6” centers.  For going through bulkheads you can drill the proper sized hole, remove the core, and fill the core area with micro.  After curing, redrill and insert the tube.  I made the holes slightly under-sized so that the tube would fit snuggly.                                                                         

Hal Woodruff    22.7 hrs