Cycles exclude object refelction from render

Dear all,

I am new to blender and created my first model. It is supposed to illustrate how streams flow in a reactor.
Basically I built a cross section of the reactor and added arrows for illustration (Part of the picture is shown below).

Now, rendering this with cycles the arrows (mixed shader diffuse & glossy) cast a reflection on the glass face below.

Is there a way to aviod this?