there are so many ways on how to create vacuum, a garden hose
fitted with empty plastic bottle of softdrinks or mineral water,
bottom-cut will do. if you want with pressure, use the powerhead
fitted also with similar bottom-cut bottles and long hose for the
discharge area. whenever you push the suction end at the gravel,
all dirt embedded to it will be thrown away.....
making your own tank could save you 50% of the cost. however, when
you bumped or hit something, and chipped off the edges, it will cost
you the same or more. plus, you can directed your time in a more
productive effort