Bottom frame of Glass tank??

[Mastiffman]

If the 30 is made properly there is no need to replace the frame. Thats with the sides sitting on top of the bottom pane. You also have to place the tank properly with the full support of the bottom and perfectly level, on a piece of foam is best. But if you want to replace it glasscages.com has frames fairly priced.

UNfortunately they don't carry anything above 90gallon tank frames... from what I saw....

 

[MTWiley]

You might try giving them a call, their bigger tanks come with bracing around the top, so I'd assume that they have them for the larger tanks. I'd guess that there probably isn't as much demand for the larger replacement frames as most people don't have larger than a 90 gallon tank so they might have them, but not list them on their site.