Fluval 403 Instructions

Updated November 21, 2016

Every fish aquarium needs some sort of filtration to ensure the health of the fish. Keeping the water clean, adding oxygen and creating a water flow in the aquarium are just some of the benefits of a filter. One aquarium filter is Hagen's Fluval 403. This canister filter holds many types of filtration media while operating with a unique dual spray bar system. Setting up the filter requires a few important steps to ensure the machine will run smoothly and not spill water on the floor. Once it is set up, the filter should continue operating and keeping your tank healthy.

Unfasten all of the clips on the top rim of the canister, including those holding the motor onto the case. Inside the case you should find the media baskets, which will hold the carbon, ceramic rings, filter pad and other materials that will filter the tank. Remove the media baskets.

Twist apart the media baskets until they separate. Rinse the media inside each one to ensure there isn't any dust or debris. Reassemble the media baskets and replace them in the case.

Locate the seal ring, which is found between the motor and the case. Stretch the ring to make sure it doesn't have any kinks. Wet the seal ring and replace it on the case. This will help make sure the filter doesn't leak.

Reattach the motor to the case and clip it into place.

Place the Fluval 403 filter somewhere outside of the tank. This can be in the aquarium stand or a nearby cabinet. Just make sure the filter is positioned below the tank's waterline.

Measure and cut a piece of aquarium hose to span from the filter's intake spout to the rim of the tank. Do the same with a piece of hose for the exhaust spout to the tank, too. Then cut two 2-inch hose lengths that will be used on the connector valves.

Attach one two-inch hose on the intake spout. Place the other two-inch hose on the exhaust spout. Lock both hoses in place with the hose locknuts. On the open end of each of these hoses, attach the connector valves and lock them in to place with hose locknuts. Then attach the long hose lengths to the connector valves using hose locknuts. Attach adjustable rim connectors to the end of the intake and exhaust hoses using hose locknuts.

Place a strainer on the bottom of the intake stem and attach a rubber elbow to the open end of the stem. Attach the elbow stem to the adjustable rim connector on the intake hose.

Attach two suction cups to the intake stem and place the suction cups in a desired location inside the aquarium. This can be in an area hidden behind tank decorations.

Place two suction cups on the spray bar of the filter. Unlike most filters, the Fluval 403 model can use two spray bars joined with a connector hose, which will create a broader current in the tank. You have the option of using one or both of these spray bars. Whether you're using one or two spray bars, attach a rubber plug to the end of one spray bar. Place a rigid elbow on the open end of the spray bar.

Open the valves on the intake and exhaust of the filter. Use your mouth to suck air out of the exhaust. This will create a siphon effect and water will flow through the intake side of the filter and into the case.

Attach the rigid elbow, which is connected to the spray bar, to the adjustable rim connector on the exhaust once the siphon effect is complete. There shouldn't be any water in the intake hose or the case.

Plug the filter into an electrical supply. Make sure the spray bar is distributing water evenly through the bar. If air is trapped in the case, tilt the filter until all the air escapes. The Fluval 403 should now be filtering water through the aquarium. Leave it plugged in for continuous filtration.

Things You'll Need

  • Fluval 403 filter
  • Aquarium hose
  • Hose locknuts
  • Seal ring
  • Media baskets
  • Media
  • Hose valves
  • Suction cups
  • Intake stem
  • Intake strainer
  • Exhaust stem
  • Exhaust stem plug
  • Rim connectors
  • Exhaust rigid elbow
  • Intake rubber elbow
  • Hose brackets
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