Product: Fluval 1-4 Internal Filters
Manufacturer: Hagen
Price: $20-(5-10 gal) <--> $45-(20-50 gal)
Pros: A great little filter with 3 media areas allowing you to choose your own media for running it. Can be used as a secondary or primary filter, movable nozzle, adjustable flow rates.
Cons: With the advent of the external power filter, few people want a filter that is located in the aquarium itself. Difficult to clean and remove from the aquarium.


Hagen is a well-known manufacturer of many aquarium items. In fact, they may have the largest catalog of aquarium supplies out of any manufacturer that I know. Unfortunately many of their items have the reputation of being cheap despite who well they actually work.

The Fluval 1-4 series is an increasingly hard to find series of internal power filters. Due to the difficulty in cleaning internal power filters, in time I am sure they will go to the dinosaur. However, I personally own both Hagen’s Fluval and Penn Plax’s Shark series of internal filters. For special purposes, i.e. short term extra filtration, secondary filter, these filters are great. However, I don’t believe I’d use them as a primary source of filtration on any tank.

Maintenance (5)

NO matter how you look at it, internal power filters take a lot of maintenance. The filter media is inside the filter and the filter is inside the tank. Therefore to change the floss/carbon, you are required to remove the filter from the tank and then remove the media from the filter. It is a messy job. The Fluval internal power filters include small plastic cylinders which act as a tube coming from the intake of the filter. Water enters the filter, passes through any floss you have added, and then enters this sectional tube. In the tube you can place ammonia chips, carbon, peat, or anything else you desire. Unfortunately, the tubes are very hard to fill, and no matter how I did it, I always made a mess of things. The filter holds together very well. While this is great in the aquarium, it makes taking it apart to add new filter media very difficult.

Noise (8)

Once nice point about having an internal power filter is that the water serves as a damper on the noise, that being said, I really wonder how noisy the fish think this filter is.

For the most part, you won’t hear the filter unless you’ve gone way too long in-between cleaning out the filter media, so noise is usually not an issue.

Durability (9)

As mentioned before, Hagen is often accused of making cheap aquarium products. (notice I didn’t say wrongly) However in the case of the Fluval internal filter, this is not the case. The Fluval is extremely durable and will take quite a licking. If you forget to change the media for 3 months, the water flow will slow drastically, but you probably won’t burn out the motor. I’ve infact gone 6 or more months without cleaning the filter to no visible adverse effects. The case of the filter is built of a hard sturdy plastic, and the parts inside are not prone to breakage unlike the fluval’s bigger brother canister filter series.

Quality (8)

For what this filter is intended to do, it does a great job. Again, this filter should not be used as the only filter on a tank. However, if you have a planted aquarium, it may suffice as the only filter. The Fluval internal filter gives you the option of using different media in the filter, which allows you to filter with carbon, ammonia chips, or whatever else you’d like. This filter would work great to help dispense peat in a tank that you wanted to use to breed the blackwater and softwater tetras.

Overall (7)

I still believe that internal power filters are going to go the way of the dinosaur. Most aquarists who buy filters for smaller tanks tend to be beginning aquarists. Most beginning aquarists like filters that are easy to maintain and that don’t require them to get their hands wet. Due to this fact, the Fluval Internal filter may not be on the market much longer. However, this is a great little secondary filter that I do suggest buying if you find one on sale. I personally am using mine in a river tank at the moment to create a waterfall. This is a great compact filter that can be hidden away and still do a good job of cleaning the water.

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