Building a tank

[Crawdaddy]

Got the bright idea to try and build a tank from scratch. I was looking at something between 125 and 150 gallons. Has anyone here built one? If so any advice before I get started?

 

[Badambomb79]

I saw a garf calculator that you type in the dimensions say 48x24x24 and it will tell you the gallons the tank will hold and all the exact cuts for the glass/acrylic