Will 12 inch subwoofer be enough for an 18x20 room (with 10 ft cielings)

I have an SVS SB2000 (sealed box) that has a 12” driver and goes down to 19Hz within 3dB.  I have a similarly-sized room that opens to two medium-sized rooms, and with the right movie the floors literally shake so I doubt you’d have a problem with the “enough” part.  You don’t really give enough detail to go any further than that though.  FWIW. 

Room layout dictates I can't have more than one sub.

Blast that room dictator! Who does he think he is to tell you what you can and cannot do? Oh well. We get the government we deserve, I guess is true after all.

Blast that room dictator! Who does he think he is to tell you what you can and cannot do?

Yeah, he’s a bad dude just like his evil brother the cabinet dictator.  Really hate that guy too.  Lest we not forget the mother of them all — the wife dictator.  Dedicated rooms and divorce are the best weapons we audiophiles have against such injustice.  Yeah they’re expensive, but you get what you pay for. 

Buy2 subs it equals out 60 hz nulls in the room
best sub by far and you can get  for under $2k delivered,for 2.
free shipping 45 day audition and free return if not satisfied with a great app the most high tech 13 inch to below 18 HZ ,and 5 year warranty with a Transferrable warranty ,Check it out 
sub of the year the SVS 3000 SB ,and is a smaller version of the great ultra 16 sub, Ano other sub has a Dual pole piece meaning even at low volume tuneful Bass . I bought them last year and I owned several $1500-$2k + subs