It is a bummer to lose the tank ( I know cause in the process of building my tank I encountered a leak or 2 along the way and 300G is ALOT of water
) ... you do seem to be quite talented at DIY and scrap glass can be had for cheep ( er cheap ) ... GE 1200 silicone ( look in the phone book under silicone wholesalers ... 5 bucks for caulking gun size tube )
Point is that as bad as it is now you can change that fairly quickly if you really WANT to. Been there and done that but if you need anything just let me know
Cheers