The Fluval Flex aquarium range is one of the most popular starter and mid-level tanks thanks to its modern curved design, built-in multi-stage filtration, and customizable LED lighting. Whether you’ve chosen the 34L (9 US gal) or 57L (15 US gal) model, this guide will walk you step-by-step through unboxing, setup, and aquascaping so you can create a thriving aquatic environment.
Step 1: Unboxing Your Fluval Flex
When you first open your Fluval Flex kit, you’ll find:
- The curved-front glass aquarium with integrated rear filtration compartment
- LED lighting unit with remote control
- Circulation pump with output nozzles
- Foam block, Poly-Carbon cartridge, and BioMax media
- Safe low-voltage transformer
- Spray bar (included with the 57L model)
- Anti-slip mat (to protect surfaces)
Before you start, check that all parts are included and inspect the glass for any damage. Rinse the tank gently with warm water (no soap or chemicals) to remove dust from manufacturing or packaging.
Step 2: Positioning Your Aquarium
Choose a sturdy, level surface that can support the full weight of the tank when filled. For reference:
- A 34L Fluval Flex will weigh around 40 kg when filled.
- A 57L Fluval Flex will weigh around 65–70 kg when filled.
Keep the aquarium away from direct sunlight (to prevent algae growth) and ensure there’s easy access to power outlets. Place the included anti-slip pad under the tank before setting it down.
Step 3: Installing the Filtration System
The rear filtration compartment is divided into sections:
- Mechanical Filtration – insert the foam block into the first chamber to trap debris.
- Chemical Filtration – place the Poly-Carbon cartridge in the middle chamber to remove impurities and odours.
- Biological Filtration – add the BioMax media in the final chamber to cultivate beneficial bacteria.
Attach the circulation pump and direct the dual output nozzles (or spray bar in the 57L) into the main tank. Adjust them to create the flow you want—gentle for planted aquariums, stronger for active fish.
Step 4: Adding Substrate and Hardscape
Rinse your substrate (gravel, sand, or plant-specific soil) thoroughly before placing it in the tank. Create depth by sloping it from back to front, which enhances viewing through the curved glass.
Next, arrange your hardscape elements such as rocks, driftwood, or decorative pieces. Use them to build focal points and hiding spaces for fish. Take time here—your layout will set the stage for aquascaping.
Step 5: Aquascaping with Plants
The Fluval Flex lighting system supports live plant growth (6500–7000 K spectrum). For best results:
- Place short carpeting plants like dwarf hairgrass or Monte Carlo in the foreground.
- Use mid-ground plants like Anubias, Java fern, or Cryptocoryne around hardscape.
- Plant taller stems like Rotala, Ludwigia, or Vallisneria in the background.
Mist plants with water during setup to prevent them drying out.
Step 6: Filling the Tank
Place a clean plate or plastic bag on the substrate to prevent disturbance, then slowly pour in dechlorinated tap water until the tank is nearly full.
Check that the filter pump is submerged and plug in the transformer. The system should start circulating water through the rear filtration chamber. Adjust the output nozzles to your desired flow.
Step 7: Setting Up Lighting and Heater
Install the LED lighting unit and test the remote control. Experiment with colour modes and intensity, but start with a natural daylight setting for plants and fish.
If you plan to keep tropical fish, install a heater in the rear compartment. Set the temperature according to the species you intend to keep (typically 24–26°C).
Step 8: Cycling Your Aquarium
Before adding fish, it’s essential to cycle your aquarium to establish beneficial bacteria. This process usually takes 3–4 weeks. You can cycle with or without fish, but fishless cycling with ammonia or bacteria starters is safer.
Test water parameters regularly and wait until ammonia and nitrite levels drop to zero, with nitrates rising slightly. Only then should you introduce fish slowly.
Step 9: Stocking Your Fluval Flex
The Fluval Flex range is ideal for small community setups. Popular options include:
- 34L model: small shoals of neon tetras, rasboras, or guppies, plus shrimp or snails.
- 57L model: larger shoals of tetras, dwarf gouramis, or a betta with compatible tankmates.
Avoid overstocking and always research compatibility before adding new species.
Step 10: Ongoing Maintenance
To keep your Fluval Flex thriving:
- Perform weekly 20–30% water changes.
- Rinse filter foam in tank water (never tap water) every 2–4 weeks.
- Replace Poly-Carbon cartridges monthly.
- Trim plants and remove debris as needed.
The hinged lid with feeding port and EZ-lift media basket (57L model) make maintenance quick and easy.
Final Thoughts
The Fluval Flex aquarium kit makes it easier than ever to set up a beautiful, healthy aquarium. With its integrated filtration, customizable lighting, and stylish design, it’s a versatile choice for aquascaping enthusiasts and beginners alike. By following this step-by-step guide, you’ll be well on your way to creating a thriving aquatic environment full of life and colour.
