It's filter wool sheeting (behind the wood) blue jap matting then 10L of Seachem Matrix then more jap matting then though the FBF then back to the last section of the sump then pumped back to the main tank.
I think if you have a barebottom tank a FBF would be a great way to go
You lose all that bio area with a barebottom this way you still have it but it is in the FBF.I have never had any sand returned to my sump you just need to adjust the flow slowly when you first set it up.
Ok a tank shot but I suck at full tank shots
Tank
One with the new gravel had to remove the black gravel was buffing my ph to high
Sump before the FBF
Canister filters pluming under the gravel
neo you said more pic's
Rat