Reason For high Flow rate above sand

[bitnick07]

Just wish to know the purpose for the high flowrate above the sand, is it just to prevent debrie from forming or is there other reasons.
Also what happens if i have a low flowrate?

 

[demonsp]

Im not sure but i think you mean you have powerheads pointed low and over the SB?

 

[MCsaxmaster]

Proper water flow is important for aquatic organisms. Some live in areas of very strong water flow while others live in areas of fairly modest water flow. Sands collect in areas of modestly strong flow. With really strong flow sand is washed away and all you have is larger rock/rubble. In areas of very weak flow you get silt. In between, with modestly strong flow, you get sand and the organisms that live in sand.

 

[The Cardinal]

It´s mainly for suspending detritus etc as well as providing sufficient oxygen to the sandbed (advection).

 

[Randy Holmes-Farley]

Adequate flow (and hence pressure differentials) other the sand may also drive slow movement of water through it, and that may help the denitrifying effects that may otherwise be very limited by diffusion rates.