Keeping a fish tank is a hobby that has become more and more popular among pet enthusiasts. Whether large or small, a colorful fish tank sure makes your house more lively and fun.
In order to keep the fish and plants healthy, you need to take good care of the aquarium tank. That means you need to clean all the messes in your tank, and as often as possible. There are more things in an aquarium tank that can affect the cleanliness and water quality than you might think.
There are excess food, algae growth, dirt and other debris in the fish tank. Some of the pollutants are large enough for us to pick out by ourselves, but not all the pollutants are. To clean and purify the fish tank properly and regularly, you will need the help of a fish tank filter.
Choosing the right type of fish tank filter can be difficult because there are so many options available on the market nowadays. Some of them are great products, while some others cannot really do the job as well as you would expect.
In order to save you some troubles of having to go through some test failed products, today we’ll introduce and review one of the most popular and well-liked aquarium filter out there. It is the Fluval 306 External Filter.

Table of Contents
Fluval 306 Canister Filter Review
Size and Dimensions
The Fluval External Filter comes in five different options: Fluval 106, Fluval 206, Fluval 306, Fluval 406, and Fluval G6. Among the options, the Fluval 306 is by far the most popular choice for many people because of its medium size.
The Fluval 306 is not too large of a device. It is only 18 inches height, 10 inches length, and 7 inches width.
In another sense, the device is only a little bit bigger than the palm of a hand. Even though it can be considered a small device, compared to other aquarium filters, it is a medium size.
Thanks to that, the device can fit into smaller tanks while still being able to handle the workload of larger tanks as well.
Aquarium Capacity
The Fluval 306 can handle the filtering job of an aquarium that is 12 to 70 gallons large. So in other words, for an aquarium as large as 70 gallons, you only need to use one Fluval 306 filter and it will efficiently take care of the job.
Furthermore, the Fluval 306 is suitable for use with both freshwater and saltwater aquarium. So even with the extra salinity in the water, the filter can still have no problem being its usual efficient device.
Advanced Motor Technology and Canister Filters
The device is not designed to only filter the water, but it is also designed to filter the water well. The filter is equipped with canister filters that do not only offer superior filtering capacity but also a powerful flow rate. The canister filters provide superior filtration, which is ideal for both fresh and saltwater in a large amount.
Canister filters normally maximize a device filtering capacity by taking advantage of their large filter body. The Fluval 306 is designed to give the filter as much space as possible in the body for the filtering process to be the most effective.
Multiple Stage Filtration
The Fluval 306 has three stages of filtration. This is one of the selling points of this product. The three media stages of the device include a mechanical, chemical, and biological stage.
The mechanical stage requires a large capacity of space. This step uses up most of the space within the device. The vertical twin foam pre-filters absorb more debris and prevent clogged media in the filtering process.
In the chemical and biological stage, the water is treated with chemical and biological processes. Both these two stages are placed in independent modules which allow easy and mess-free media removal for the water.
Aqua Stop Valves and Lift Lock Clamps
These are also special features of this device. The AquaStop valves and the lift lock clamps are maintenance features that help not only keep the device function perfectly but also make it hassle-free to maintain it.
The AquaStop valves help stop the water flow without having the owner disconnecting the hoses by themselves. Besides taking away some burden from the owners, these valves help eliminate leaks and mess as well.
The Lift Lock Clamps help securely and quickly lock the motor housing in place.
Pros vs Cons
Pros
- Suitable for many sizes of aquarium
- Suitable for saltwater and freshwater
- Quiet
- Powerful flow rate
- AquaStop valves and Lift Lock Clamps
- Come with media included
Cons
- No output flow height detector
- More expensive compared to other products
Conclusion
Even though this filter is a bit more expensive than other devices on the market, it can be worth it if its features are what you are looking for. It is hassle-free to maintain and generally pretty self-efficient to clean up and keep itself neat. Besides, all the filtration features are top-notch and efficient. It is one of the most well-liked and reviewed aquarium filters out there.
Stay away from this filter! I have one for approx. 4 months and having nothing but issues with air pockets and noise. Even working with fluval doesn’t help much and if you search around many are having same issues. Unfortunately after two months I’m stuck with this garbage and would probably just toss it in the garbage rather than paying shipping both ways for a repair/replacement. Loosing faith in FLUVAL PRODUCTS…
I own the fluval 106 and 306. Absolutely love them both. You may want to check for user error. I haven’t had a single problem the year I’ve owned both. Super quiet and does a heck of a job filtering. Purchased both my filters off of amazon. I won’t ever shy away
I use nothing but fluval filters on all my 15 tanks and never had a problem with none of them,from job,filters to the fx4, fx5, fx6, 406, 306, and all the hang on backs of every size , never a problem with any of them ,,, I highly recommend them,
Biggest piece of trash. On our 3rd one now after motor issues with one, clamp issues with another and everyone of them leaks around the seal to the motor. This is after replacing seal and using recommended lube from Fluval. Sure we got the store to replace the bad motor one, but had to put out for the other and then add up all the parts for maintenance and to fix leaks. We wont even get into the time trying to stop leaks and clean up after them. Out of the blue it will just start to leak around the seal for no reason. Like I said nothing but trash don’t waste your time or money.
GOT MINE USED FOR 70.00 DOLLARS FROM SKOOLS OF FISH IN RICHMOND VA. ITS ON A 55 GALLON TANK. I HAD TWO MARINELAND 350 BACK FILTERS. THIS 306 DOES THE JOB HAD IT FOR TWO WEEKS. YOU CAN’T HEAR IT RUN. I’LL NEVER USE MARINELAND AGAIN. I NEED A FLUVAL FOR MY 92 GALLON . CORNER BOW FRONT. I HAVE BEEN KEEPING FISH SINCE JUNE OF 1967. THIS IS THE BEST YET.
I absolutely love me two fluval filters. I own a 306 and a 106, also currently in the process of purchasing the new 407. If you do the routine weekly maintenance and take care of your impeller/motor area you’re golden. I recommend buying a bristle brush set for cleaning. Watch a few instructional videos on dissembling the top half for proper preventive maintenance. Both filters that I own been running for a year with no issues and same gasket with no leaking. One thing to note is sometimes air gets trapped inside after water changes even after priming. I just give it a good tilt to release the air and it gets silent again, but that’s mainly for the 106. Love the brand A+