The valve appears to be a flat cap, there is no injector on the top, just a block off plate. Filox is a backwash media. I believe the original media was birm, just backwash also. The air injector was to help the media attrack the iron. Some water treatment sights mention air/oxygen injection to help the media perform better. Just wondered if leaving the air charger in line is a good idea.
I will also look for a 1.5 cu ft tank.
Actually the air was to allow the Birm to oxidize the iron. Air will also oxidize some of the iron. Birm can not work unless there is 15% dissolved oxygen in the water.
Birm can not be used if any H2S is present in the water.
I wouldn't use the air injection for Filox because it will cause ferric iron particles (rust) on top the Filox.
You will need the correct DLFC button for Filox; Birm is much lighter and will have a much smaller gpm DLFC. And less time for backwash and rinse positions.