Using Lr Rubble In Rear Chambers

[westiemarble]

When LR rubble is used in the rear chambers of tanks such as the Orca 450 and 550 how does it assist in the biological filtration since light cannot penetrate to the bottom of the rear chambers. Don't the bacteria which is supposed to colonise the LR rubble require light to survive?

Thanks

 

[kj23502]

No the bacteria doesn't require light to survive