Sand and gravel in a sump?

[fwiffo]

that's a commercial setup for a water treatment plant. they say that these are awesome as a lining collects on top of the sand (the yellow "filter media" stuff in the diagram), cleaning the water to a super high degree.
but does it smell? bet it does. would you use it?

would gravel be good to use in a tank as a sump media?

thanks.

 

[TRENT]

I know a guy that uses a setup like this for his 17000 gallon pond (DIY setup). seems like it works for him.

 

[Pharaoh]

Looks like it should work, but I probably wouldn't use it.

 

[fwiffo]

what about using gravel as a mechanical media. would that have any drawbacks?