With the introduction of LEDs, you lost a lot of electricity requirements. They run at a fraction of the power plus no need for chillers. I couldn't imagine any standard sized tank needing more than a single 20amp breaker to power it. Mind you, that's based off the recommendation that any circuit should never be regularly pushed passed 75% capacity, or 15amps.
But like Gregg said, if you can find the wattage or amperage that each device uses, then you can calculate your load. I'll help you with any of the calculations if you need it.