Raise your lateral to maintain 1% or better slope and run all 5/16. Avoid 3/16 . 3/16 is best suited for 10% slope or more you are going to get less sap with the 3/16 even with vac, keep the 5/16 tight and a nice slope to your shurflo pump, keep the pump wet and you will get the most sap your going to get, , 2- 15 tap lines would be better .