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Fluval 305 with apple for reference on dimensions Fluval 305 with apple for reference on dimensions

The Fluval 305 external canister filter outputs 260 gallons per hour, and is designed for aquariums up to 70 gallons,. For my 55 gallon African cichlid tank, I find it performs well. By purchasing it on Amazon, I was able to save about $70 from the price at the local pet shop.


Fluval 305 external canister filter.

The external canister is designed to be placed below the aquarium. An intake and output hose extend from the canister into the aquarium. From the intake valve, water flows down through four foam screens, trapping large particulates. Water then travels up through three stacks of media baskets, where mechanical, chemical, and biological filtration occurs before passing through the outlet hose. The entire canister assembly is water tight. If the rubber gasket is improperly installed, the canister will leak very quickly. If properly installed, the assembly is reliable.

My ideal configuration for a Cichlid tank. Water polishing pads, ceramic rings, and ZeoCarb

Two rim connector assemblies hook the hoses over the rim into the tank. The outlet hose has an outlet nozzle to shoot the water out in a wide stream. The intake hose has an intake tube that extends towards the bottom of the tank, with an intake strainer at the bottom. The entire assembly is solid.


Out of the box, the media baskets come with 3 carbon packets and 3 trays of ceramic biological filters, arranged according to manufacturer recommendation. The carbon lasts a month of use.

Assembly takes half an hour to an hour. There is a manual and quick assembly guide, as well as an instructional DVD to walk through the assembly and usage. I suggest referencing these resources carefully.

Fluval 305 assembly

Before assembling the filter, it is important to note that the distance from where the canister is set down to the top of the water level in the aquarium must not be more than 4.5 ft. I suggest measuring the distance between where you set the filter and the water line of the aquarium. You might have to build a shelf or stand to raise the external canister to the 4.5 ft mark.

Another important consideration is that the water level should never be more than 7 inches below the aquarium rim. Also, the canister should never be installed above the water level.

The intake and outlet hoses as seen at the rim assembly.

Out of the box, a single hose is included, the hose must be cut into two pieces for intake and outlet. The hoses must be long enough to extend 4 in. beyond the aquarium rim, and the intake hose should be 3 in. below the water line. I suggest, if possible, leaving additional slack when cutting the line, as you will probably make adjustments in your positioning of the canister and adjustment of the rim assembly.

The rubber gasket must be placed on the canister cover before assembly is completed. It is important to note that the gasket slides on the cover, and is not pushed with force into any grooves. I suggest zooming in on the following photograph to observe the position of the gasket. When I first installed the gasket, I put it on incorrectly, and it resulted into heavy water flow out of the canister when I primed it.

Notice the placement of the gasket on the Fluval 305 external canister filter.


Operation is smooth and quiet, almost completely silent. The catch being the outlet nozzle. Because of the power of flow, if the outlet nozzle is placed above the waterline or less than an inch below, there is a sound of rushing water. The outlet nozzle needs to be placed at least an inch below for quiet flow.

For my 55 gallon African cichlid aquarium, I have a combination of filter media that has led to crystal clear, clean water. Water circulation is healthy, and the flow is not overwhelming for the fish.

I feel comfortable going a month without cleaning out the filter, provided the fish are not overfed. I still like to clean the tank itself once every two weeks.


The hoses can be sealed off and removed from the canister for easy cleaning. The external canister will be full of water and is heavy to lift.

Removing Fluval foam inserts.

The cleaning is straightforward. I scrub the internal structures with a bristle brush. I rinse the foam prefilters in warm tap water. I avoid cleaning the ceramic biorings, in order to insure a healthy bacterial colony. In a similar vein, I avoid replacing all the biorings at once. I stagger the recommended 3 month replacement schedule.

Recommended Configuration

I utilize the following configuration for my 55 gallon African cichlid tank:

Top tray: Fluval Biomax Bio Rings with Fluval Fine Filter Water Polishing Pads

Fluval Water Polishing Pads help clear up cloudy water, and are recommended to be placed on the top compartments of Fluval filters.

Middle Tray: Fluval Biomax Bio Rings with Fluval Zeo-Carb

Fluval Zeo-Carb filters contain both activated carbon and an ammonia remover. These filters are good for tanks with ammonia problems.

Bottom Tray: Fluval Zeo-Carb

Where to Buy

Your local pet supply store may stock the Fluval external canister filter product line. I found that I saved about $70 by purchasing the filter on Amazon

Alternative Fluval External Canister Filters

The following Fluval external canister filters are similar in design to the Fluval 305, but have different gallon per hour outputs, quantity of media baskets, tank size recommendations, and power consumptions.

Fluval 105 External Canister Filter: for tanks up to 25 gallons. 125 gallons per hour circulation.

Fluval 205 External Canister Filter: for tanks up to 40 gallons. 180 gallons per hour circulation.

Fluval 405 External Canister Filter: for tanks up to 100 gallons. 340 gallon per hour circulation.

And finally, some charts for flow rate, capacity, and power requirements of these models:

Flow Rate and Capacity:

Fluval filter chart

Power Requirements:

Fluval Power Consumption

Related Reading:

  1. How to Clean Aquarium
  2. AquaClear 50 powerhead review
  3. What to Feed African Cichlids
  4. How many African cichlids in a 55 gallon aquarium?
  5. 55 Gallon African Cichlid Aquarium: Supplies
  6. 55 Gallon African Cichlid Tank: Setup, Maintenance
  7. 55 Gallon African Cichlid Tank: General Observations

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