Hey Dave,

Being you have a large tank, I would attempt to put the CO2 output unit
(reactor, etc) near the middle of the tank possibly in the back wall. This
is where I have mine setup.

Reason for doing this is that the Co2 will travel in both directions in the
tank equally (or there abouts) so that you don't see one side of your tank
flourishing and the other side just slowly growing.

Just my two cents.

Brian S.
"Dave S" wrote in message
...
I have a planted 400 litre tank; the spray bar is at the back covering
approx half the length of the aquarium, the intake is at the other end in
the corner - What is the best position to locate the Reactor, hidden in
the
corner behind plants, or in the centre?

TIA - Dave