Long And Thin Or Short And Fat?

[cynic]

I'd be worried about a table too, 300l of water is 300kg plus sand/gravel pluss, if you have decent glass (mine is all 10mm) the tank its self will go 40/50kg.

You could be looking at 400Kg worst case 24/7, if the table settles even by only 5mm that could crack the glass or the sealant over time.