[Subtletanks91]

Think about the beam angle like this.

Here is a 90* angle. /-------\ obviously more coverage if you have it directly on the tank. If you hand it however more light will be shot over the tank instead of in the tank.

Here is a 45* angle. /--\ Now you see if this is directly over the tank it will only hit the center with light. But if you hang it say 5-8" above the tank it will cover the same amount of space the 90* would sitting on the tank. Long story short if you hang the 90 you loose light.

 

[Subtletanks91]

That's true. But if you raise a 90 up say 7" you'll loose alottttt of par