sink sump

[TANGOMAN]

I'm looking for a way to reduce/eliminate the buildup of sand etc. in the house's plumbing system. I have one of those large plastic sinks down in the fish room. In the winter months, that is where I must rinse gravel, sand etc. The wife doesn't enjoy a gritty tub when she has a bath, even after trying to convince her it helps exfoliate the skin...
I'd like to devise a "settling chamber" prior to the drain stack. I've seen a unit at a local bottle depot that appears to be a settling unit but given the smell of those places, I'm always in a hurry to leave.
Has anyone played around with this concept ?