The main reason why I prefer this system, is that the tank is off the ground, and the pump if you are installing one, will always have a positive flooded suction.  Yes, there is the downside, it will probably cost more, but I do believe its worth the effort.

Our tank stands are manufactured out of 50mm x 50mm x 2mm (2inch x 2inch) RHS (Rolled Hollow Section) tube, fully welded.  The cross braces should be no further than 300mm (12 inches) apart, to support the timber base.

If your tank stand is to be placed on an existing path, weld 150mm x 150mm x 6mm (6 inches x 6 inches) plates on the bottom of legs, with 2 x 10mm holes in each for fixing to concrete,

The ideal timber for the base is 65 or 90mm x 19mm Treated Pine, Merbou or Jarrah.  Fix timbers to the stand with Stainless Steel Tek screws.

With this Tank Stand system, allow for your preferred height off the ground, plus 400-500mm to be concreted in.  On the bottom of the legs, weld on spikes, 10mm round bar, 75mm long.  These will embed in the concrete to hold stand solid.