I agree get professional advice, maybe you could visit to some real aquariums parks or zoos and ask for advice, even the glass specilist should be good info. I am planning on expanding my pond and I went to some exernal pond/.fountain specialist who sais fiberglass is the best thing to not have leaks and cracks,,maybe this in conjuction with the proper glass could help. Also be sure to have a huge bio filter, uvs and everything you could get to make that water clear,otherwise you don't want to have murky water or grean algea covering your glass.