Hi there Francis
Its nothing special or DIY in this tank,
Just 2 Aquael UNI filter UV 750 behind the BTN and a Fluval 405, the in take behind the BTN and out take i drilled in to the BTN. so its quit turbulence behind the BTN:)
Many people use the hole background as a filter aera of the BTN as a filter but i wanted to keep it simple to clean when ever i need to.
Hope this will be OK in the long run.