Hey Nick.... you need to find the breaker that supplies power to your outlets. The cheapest way of doing this is by flipping off each breaker one at a time, then going around to each room to see what was turned off, when doing this you may want to shut everything off but a light in each room. I used a small light & went to the room that the breaker turned off and plugged it in to every outlet, sometimes one breaker will cover several rooms, so take notes, & make a list, this is time consuming I know but will pay off later. Once you get a complete list, you can see what size breaker/s that feed your aquarium, & other devices. In most post-modern homes the big electrical demands were, kitchens, I.e., refrigerators, toasters etc. The other was your central A/C/electric stoves, which big ticket items used 220v double pole breakers, usually they are very obvious in the breaker box. Modern homes, electric water heaters, microwaves, dish washers, dryers etc. so they have larger breakers supplying those areas, sometime several breakers feed the kitchen (I think I have one 50A for the stove, one 30A & one 20A in my kitchen). The under sight until recently has been the living room, this room these days also use up lots of power. Most all other rooms can span one breaker with no problems. As you make a list, on the breaker panel, either write the rooms each breaker supplies or post a detailed list next to it, in emergencies it will be helpful. In an older home, it may be difficult to power a huge reef & maintain a safety factor, It could be as easy as adding another breaker & dedicated line to the tank area, or it could mean totally breaker box replacement, then adding another line to the tank area, this is when you will need to call in a professional, certified, or at least well experienced in retrofitting & meeting the proper codes in your local area. Now that I scared you, LOL, you can use plan "B", after locating all of your breakers & their feeds, you can devise a split on power maybe. Try and use two separate breakers, & save you lots of cash. One good thing about breakers, if you are pushing them too far, they should trip (if properly wired in the first place), that is their purpose, if you do trip a breaker, then it is time for alternative planning. I hope this helps Nick.
