Yeah because we have a Double-Bull blind and it has worked great in the past. The problem I found is that I think a lot of times deer get ambushed at water by predators, so they're naturally inclined to be super-cautious when approaching. Even when they made it all the way in, two or three quick sips and the bounced.
You have a good point about setting up off the water a bit. I think I will put a treestand on their trail about 200 yds above the tank. They spent a lot of time meandering around on the knob above the tank checking things out before they commited. If I would've had a stand I could've smoked EVERY critter that came in that night!