You can have as many devices as you want sharing the same address, so if you can get the timing correct either of your methods would work. You could also use a scene capable appliance module, but unfortunately the only one available is the rather expensive ACT RF104. I think doing this with a RLY8-XA (www.appdig.com) may be your best bet, along with an Ocelot to control the programming. We are starting to sell a lot of the to Aquarium users. HAs a lot of other capabilities useful to your hobby.

Bill
www.homeautomationnet.com