Fluval Sea Flex Saltwater Aquarium Kit 123L- Black Aquarium Review

Image of The Fluval Sea Flex Saltwater Aquarium Kit — All You Need to Get Started

The Fluval Sea Flex Saltwater Aquarium Kit 123L- Black is a large aquarium that measures 32″ long and can hold up to 180 gallons of fish and water life. It has a unique placement of locations to add decor, ornaments, and fish to the tank. The Fluval Sea Flex Saltwater Aquarium Kit 123L- Black shares the top to bottom bow front, integral filtration, and lighting of its smaller relatives, but can hold twice as much water (32.5 gallons), have more room for a protein skimmer, and have marine spectrum app-controlled lighting.

The new Flex’s filter portion resembles a weir box, which is centrally positioned instead of spanning the whole length of the tank. It has a Y-shaped dual return, flare nozzles and two pairs of intake ports for top and bottom scavenging. The filter box houses a 214gph pump, twin filter foams for mechanical filtration, carbon for chemical filtration, and Biomax ceramic media for biological filtration.

If you choose to add these accessories, there is space for a heater, protein skimmer, and other media. However, they are not included in the kit and must be purchased separately. The cabinet includes a place for an automatic fish feeder.

Marine 3.0 LED

The aquarium light features 252 LEDs, which generate 1800 lumens using 42 watts of power. The unit comes with three presets—sunny reef, deep-sea glo and color boost—and offers custom color capabilities and moonlight functionality. It also has 24-hour programming and is rated at 25000K. Running passively enables safe and quiet operation, while IP67 waterproofing allows installation above or below the waterline. A second unit may be installed next to the first for increased coverage.”

It’s great to see that Hagen has found its place in offering entry-level saltwater aquariums for the larger fishkeeping market. We recall when Hagen made its initial step into marine aquariums with the Fluval Sea collection.

The Fluval Flex Saltwater Aquarium Kit, also known as the Fluval Flex 123L Marine in Europe, may prove to be very attractive to novices and seasoned aquarists alike. It offers greater swimming area and water volume than the Evo while still having the same straightforward features.

The option of a starter tank with a lid, to keep fish in and other pets out, is excellent in a sea of bare rimless aquariums. And although equipment is simple, we welcome the inevitable DIY tank modifications and Instagram-worthy coral collections that will undoubtedly follow.


If you are looking for the perfect tank to house your fish and other sea life, the Fluval Sea Flex is the tank for you. This aquarium has a sleek, modern design that will look great in any room. It also comes with a water pump and LED lighting so that you can start with a beautiful tank immediately. You can even add a background to your tank if you so desire. This Fluval tank is perfect for novice fish keepers, as well as experienced fish keepers.