tank is sloping forward...

[Delphinus]

Not to overharp on a point, but how come? No rubbermaids or bathtubs that could serve temporarily?

Don't get me wrong I have no idea what I'm talking about when it comes to big tanks. I'm just thinking in terms of logic ... shimming up a tank that's empty has got to be less stresses than a tank with water ...

I'm assuming your reluctance comes from that the water must be mixed salt already ... if it was freshwater still I'd be suggesting just let it go, and refill.

If you want to wait until the weekend, I can lend you my 55g rubbermaid if you wanted. It's big and clunky and a real PITA to move, but hey it's another 50 gallons of water storage. OTOH it was only $30 or something like that at Walmart, why not just run over and pick up 1 or 2 of those (or a bunch of rubbermaids, they're about 30g)? Then you're set. Down the road you'll probably end up using those rubbermaids for something else anyways so it's not like it's a wasted investment..

Just my $0.02 ... good luck with whatever you decide!!