I have settled on and ordered a smaller tank (60 litres, about 15 gallons) that is to be delivered today.
The water will weigh about 8.3 pounds a gallon, so that's about 125 pounds of water, and there's the weight of the tank and the sand, so figure 150 -160 pounds-ish. (Much less than the ones I was originally looking at.) I had been wanting an 80 litre, but it's both too expensive and too difficult to find something to put it on.
Basically, if the stand will support a person of that weight sitting on it without there being movement - no bending of the surface or wobbly-ness (is that a word?) - it will support the tank. So I am back down into the realm of a sturdy table or chest of drawers (if I have to) again. We saw a couple of likely prospects down at the Salvation Army, and will be going out to some resale shops later this week to check. There are plenty of sturdy coffee tables out there, but we want something that is about the height of a normal table so the tank is visible around the whole room and not blocked by furniture, as it would be on a coffee table.
Too bad about The Pier!