Flow recommendation - 400-600 gph through filter .All seams are clear and edges polished. .All units are made of 1/4" high grade acrylic which will last a lifetime. .All units are built in a professional shop by a master craftsman. .These "Do it yourself" units are fully assembled and are ready for you to setup. .Units come with a clear front/back and sides. Black for the rest of the unit. Professionally packed in a Double wall box, and fully insured. This auction is priced for quick sale. We also do custom work please contact us for custom quotes. We can build a system to meet your unique specifications 1. Water enters the first chamber from the top. (Or you can add a bulkhead.) It is here that most people add there own protein skimmer. The water rises 10 inches , but enters the next chamber 4 inches from the bottom. 2. The second chamber is the refugium chamber itself. This is where live sand, rock, macro-algae etc. is added. Most people also put a light over this section to stimulate growth and the refugium environment. 3. As the water rises to the 10 inch high mark, it spills over and enters the bubble trap chamber. This over-under chamber helps disperse bubbles from the skimmer. Some people add bioballs to this area to help break up the bubbles. 4. The water enters the final chamber through the bottom opening and into the return chamber. This is where the return pump sends the water back to the aquarium. Most people use submersible pumps and send the water back through the top. A bulkhead can be added for external pumps also. The unit is guaranteed against manufacturing defects and leaks for 3 years. If they don't leak the first day, they generally never leak. We don't have this problem as they are inspected beforehand and then professionally packed and shipped.