You can and should combine the reflection with the combination of refraction and diffuse the same way.

Here I've chosen 11% reflection.

The idea here is a photon can reflect or not, based on a probability. If it does, then there is less light to go through and light up the diffuse stuff. 

Of course, a constant reflection amount is wrong, too. What should go into this new Blender is the result of either the exact Fresnel equation (22 nodes) or my 4-node approximation, published elsewhere in the lake thread.

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Renderosity forum reply notifications are wonky. If I read a follow-up in a thread, but I don't myself reply, then notifications no longer happen AT ALL on that thread. So if I seem to be ignoring a question, that's why. (Updated September 23, 2019)