i think its the maintainence that would be a problem - how in hell would you reach the gravel!!
there's just something really not right about those tanks.
the stand being wood isn't a problem - wood is extremely strong in compression - its more the joints between the different peices of wood themselves i would be concerned about. the steel you often see used as tank stands are massively over engineered (and actually steel isn't strong in compression but in tension) but we are so used to thinking of and expecting massive bits of steel that slender steel members often provoke completely unfounded concern. trust me - i do this on a much larger scale every day. there we go thats my geek moment over for this evening