Can I plug in 2 heaters into one socket on the PC4? And if so.. If there anything else I can do this for? Powerheads, skimmer/light (those two stay on all the time)
I would highly recommend the Reefkeeper Expansion Socket. It's designed for exactly what you want to do. It has a dedicated plug to supply electricity, and a second plug that goes to you PC4 (or 8) to control whatever you plug into it.
I had my 2 wp40's and 2 my wp25 hooked up to 2 splitters into 2 outlet on same PC4. I also had two 120 3watt EverGrow LED lights (2 chords for each unit) hooked up to splitters and again hooked up to another 2 outlets blue blue then white white to two other outlets. As far as two heaters well, I don't know?