Oxygen Sealer block amounts


Oct 31, 2013
So I have a room that is about 48,000 blocks interior. Just to make this easier I rounded to 50,000 which comes to 40 sealers. Now once I place the sealers and make sure they are getting the required oxygen and power nothing happens. They stay Unsealed. I even put down more sealers in hopes I just calculated wrong, but it still doesn't help.

The sealers are supposed to fill a 1250 block area alone with more added as needed. Does this mean I need to space them throughout the room to properly provide the seal? Or should I be able to just place them all at the ceiling (which is about 50 blocks from the floor)?