Estimate shipping
The Aqua Zonic Sirius LED light unit in 45cm. A straightforward rim-mounted LED bar for a freshwater tank of around that width.
Measure the tank externally. The mounting brackets sit on the rim, so what matters is the outside width, not the glass-to-glass measurement or the stated volume.
Running it
On a timer, six to eight hours a day to start with. Extend it only if the plants are clearly using the light — the first thing extra hours grow is algae on the glass.
Spares
The Sirius transformer is stocked separately in 45cm and 60cm. On an LED fitting the transformer normally fails well before the emitters do, so a dead light is usually a cheap fix rather than a new unit.