sand is much easier to keep clean than gravel as all the fish C**p stays on the surface... however this does lead to increased hoovering of the substrate as fish C**p is black and the sand is yellow/white
I use a winemaking syphon with a rigid plastic tube on one end for cleaning, this gets into difficult areas and the middle of plant clumps, it also will not suck out lots of sand if held just above the surface