I took some water out and measured from the bottom of the top black strip to the water line.
I emptied the tank and moved the plywood and found the left rear mitered up a bit. So, I moved the plywood/aquarium off the side rail. The 3/4" plywood is now supported by only front and back rail. Is that ok using 3/4" plywood? I'll fill it up again and get new readings.
Centering the tank in the middle of the stand, I think I might be level. Checked corners and they are pretty much the same. I need to spray paint back black with plasti drip b4 I refill which will make measuring the wall side almost impossible.