Overflow
 

How close should my overflow be to the top of the tank 1"-2" ?

How high do you want your water level to be? Do you have trim along the top? a Canopy? If you can see the top edge of the glass its good to have it as close as possible then it looks better, with 2 inches glass above the water it looks funny, at least to me it does.

The tank is euro braced and the canopy will cover about the top inch of the tank. I want the water level to be as high as possible. I'm just wondering what is the minimum I should go. I don't want any chance of the water spilling over the top. I guess this also depends on my water movement in the tank.

Yes, say for instance you had a wavemaker unit in your tank, then...well.

Timely post. Went downstair to get my tape measure to find water on the floor of the mech room. Could have sworn I turned the valve to the ro/di container off...

Anyways on my tank, trim around my tank is 1.75" wide and overflow about 2.125" below top of trim. With flow, water is around bottom of trim and since I wanted to ensure I wouldn't see the waterline, my hood sits 2.25" below top of trim.