Mitch, it's a standard 10G tank. so that means 20x10x12.
Fits snug under my stand, since the stand is 21x21x29.
Mitch is right. I made the cubby because i wanted more room for my refugium, and besides, the intake area really does not to be large at all. The only thing that will be inside of it is LR
/rubble, and the hose draining from the overflow. Nothing else will be in there, so why waste the space when you could use it for the refugium. Plus.. i think the corner cubby thing just looks better overall lol. And yeah.. i really want to put 1 or 2 mangroves in there.. but i'm not sure on their needs just yet. But if they can grow under standard home depot bulbs.. then i'll definitely use a couple.
Also Carla, i thought i should mention this since i noticed you said plexiglass in a couple posts above. It would NOT be a good idea to use plexiglass acrylic for the baffles in the sump(if your doing DIY), since plexiglass is weaker than regular acrylic, and it also turns yellow overtime in saltwater. It also expands overtime in saltwater, which could cause the sump tank to crack, or to shatter which wouldn't be good. You want to use something like regular acrylic, or Acrylite acrylic.