Looks great! Although I would keep a close eye on it once filled, as the 65 is really only supported at the corners right now, as that pine doenst look strong enough to support load.
Yeah that's what I thought at first, but I've seen tank stands for even bigger tanks that are even flimsier than my setup.
Plus the 3/4" I think is enough to support the weight of the tank, especially if it's equally distributed like it is. The brace for the tank distributes the weight, the pine wood also, so I think I'm ok
The bricks are not that far apart on the sides, I think 3"
I will test to see for sure once filled if I see any curves.