foilair feeding ... ah its codswallop if you ask me, i did it at the start of growing and didn`t see any thing great about it apart from the plants like it every now and then, and only when lights out, weather the sparkling water has anything to do with it..... doubt it, as it would gas off before being absorbed, or the greater amount of it like....
homemade co2 .. well it did something, defo helped through the nute burn stage helped with the recovery for sure, and i had gaps in my little space and all..
why you worried about not circ, it would only help, as it would only keep in your co2 ....