[minorhero]

Thanks for your insight. However giving the chance since i have not flooded the tank i m thinking to dig up some soil at the back and put up a barrier between the soil n vent (a mesh with rock perhaps) to allow water to flow. I am also concern about dead zone if solely rely on the upper intake.

There is a similar intake vent on my old fluval spec v. I routinely covered it up when scaping and never had an issue. /shrug it's your tank and you can do whatever you want with it, but you don't have to change anything for your tank to run normally.