[Canadian]

With the water movement in the tank you're going to get a rippling effect that makes it less than ideal to view the clams from above unless you turn off the pumps in a standard tank like you have described. What has typically been done in the past for clam tanks is to have the front pane of glass sectioned into 2 pieces such that the bottom piece only extends to about 1/2 the overall height of the tank and the second piece then runs inwawrd at about 60 degrees (N of E when viewed from right the side). I'll try to find some pictures of what I'm describing just in case it's unclear, but I have to get going to class so it'll have to wait until the afternoon.