Dick,
I have done the water test with diffuse monochrome light as per Porter in ATM-I. I had to slowly reduce the thickness of the water with a eye dropper. It was no more then a 1/16" thick when the fringes appeared. They start out as a tiny circle and as the level of the water is reduced they spread out. They were the best seen just before I could see the surfaces of the water start to distort from the surface tension with it and the edge of the glass.
Greenglass, the thickness of the water and the use of reflections of the bulb I bet are your problems. Try shining a laser at the surfaces and looking at the reflection on the ceiling. You need to adjust the level until all of them are on top of each other. Also trying viewing thru a red filter. The fluorescent light isn't monochrome enough and I find a simple red plastic filter good enough to isolate the red line from hydrogen. As Dick has stated they are fainter then viewing with two pieces of glass. Also remember that when you do see fingers, they will appeared curved even if the surfaces is flat. You need the collimate light and the ablity to view the fringers on axis to get them to appear without distortion.

- Dave