Best way to clean gravel?

[Don Trinko]

I clean my gravel at each WC with the syphon but sometimes I would like to clean inbetween times. I do have one of those battery operated things with a bag and it works OK but sometimes picks up sand and then you have to clean the impeller of the pump.
What is the best device for vacumning the gravel? Is there anything that will get all the dirt and not the sand?
Thanks; Don T.