Why some All-In-One Aquarium have a hole on the bottom? | REEF2REEF Saltwater and Reef Aquarium Forum
![Amazon.com : PENN-PLAX Cascade All-in-One Desktop Aquarium Kit – Great for Small & Tight Spaces – Marine & Freshwater Applications – 3.2 Gallons : Pet Supplies Amazon.com : PENN-PLAX Cascade All-in-One Desktop Aquarium Kit – Great for Small & Tight Spaces – Marine & Freshwater Applications – 3.2 Gallons : Pet Supplies](https://m.media-amazon.com/images/I/712UCfWiAuS.jpg)
Amazon.com : PENN-PLAX Cascade All-in-One Desktop Aquarium Kit – Great for Small & Tight Spaces – Marine & Freshwater Applications – 3.2 Gallons : Pet Supplies
![REF#: AIO132 - All-In-One Rimless Show Tank (7 sizes available) | Fish tank, Aquarium sump, Acrylic aquarium REF#: AIO132 - All-In-One Rimless Show Tank (7 sizes available) | Fish tank, Aquarium sump, Acrylic aquarium](https://i.pinimg.com/736x/06/17/60/061760ec08e054d00dd78f44c39470e7.jpg)