Another 4 the sparkys 240 to 110???

So how do we do it? The wire needs to be re ran right? I want to take 240 V by 100 amp (two 50 amp breakers tied together) and make it 110 by 50 A, Or should I just use the shared room circuit, 20 A,???

The draw will be at least, one 1000W HPS, one 600W MH, Fans, and O2 pumps, + Misc. stuff.

Thanks again