by Dominator » Sat Sep 14, 2013 8:41 am
3600W will be fine, obviously more will give you quicker heat up times and will strip faster but it will cost more to set up. A 4" bubbler will run on about 2400w and I believe a 6" will run on around 3600w. You will only ever need one controller/relay. Even if you have two elements, say you have two 2400w elements, you can have one element on and adjust between 0 and 2400w, if you want more heat, you turn the second element on and adjust the first one, that way you have between 2400 and 4800w.