As a novice to all of this, I continue to have questions.  The system I'm building is flood and drain with a 500 gallon fish tank with a 1:1 grow bed ratio.  First, I'm planning on using 1/2" delivery pipe and 1" drain pipe.  The 1/2" was based upon the recommendation in Sylvia's book.  Also, per her book, I'm planning to not cement any of the joints.  This part especially concerns me.  Any thoug…