Setting up a 55/75 gallon
So the other day I went and picked up what I was told was a 55 gallon tank. However, when I got there it was actually a 75 gallon xtall. The 75 is 48x12x30 and is setup different. It has what looks like a built in filter. Basically the back corners are squared in with glass and are setup with a ug filter and several pumps. It also has a "custom" lava rock background. I'm definitely going to remove the background but was curious about the filtration. Is it any good? Can I use sand? (I'm thinking no) any help would be good. Should I just setup a 55 instead and hold off in the tall 75. P.S. It was free.