Emperor 400

Written by Kmuda. Posted in HOB Filters


  • Hang-on aquarium power filters with multi-stage filtration
  • Aquarium filters with easy-change cartridges and media containers
  • Power filters with adjustable dual intake system for ultimate water quality

Aquarium power filters combine three filtration styles with power and flexibility. Each Emperor BIO-Wheel powerfully cleans your aquarium water through mechanical, chemical, and biological filtration mechanisms to remove debris, water impurities, and dangerous toxins. Redesigned models feature: BIO-Wheel filtration, refillable coarse media containers, and an easy-access, hang-on design with a flip-top hinged cover, plus an adjustable intake system that can simultaneously filter water from both the lower and middle levels of the aquarium for boosted filtration and water circulation. Epoxy-sealed, moisture-proof motor ensures safe operation. The 400 filters up to 400 gallons per hour through two BIO-Wheels. It includes two each of the Rite-Size "E" Filter Cartridges and 4 ounce media containers. The 280 filters up to 280 gph through one BIO-Wheel. It includes one each of the Rite-Size "E" Filter Cartridge and 4 ounce coarse media container.

Dual strainer/intake system simultaneously filters water from two levels of the aquarium: The lower (where debris, food, and fish waste settle) and the middle (where medications, additives, food particles, and waste float). In addition to cleaning the water, this process also creates greater water circulation. Plus, this improved circulation works to better mix the water and helps regulate water temperature and oxygenation levels, while preventing the "pooling" of toxins and additives within one level or area of the aquarium. For freshwater or marine aquariums. Replacement filter cartridges and replacement parts available.

Emperor Size Flow Rate Rite-Size Filter Ideal for
400 16-1/2" w x 6-1/2" d x 10-1/2" h 400 gph 2, "E" Cartridges 30-80 gallon
280 10" w x 6-1/2" d x 10-1/2" h 280 gph 1, "E" Cartridge 25-50 gallon

Additional and In-Depth Features on Emperor BIO-Wheels

Total 3-Stage Filtration Efficiency:

  1. Mechanical Filtration - heavy-duty Emperor Filter Cartridges trap solid debris like dirt, uneaten food, and fish waste. The double-thick polyfiber pad aids in removing large debris particles while permitting the water to pass through for chemical and biological filtration.
  2. Chemical Filtration - black diamond premium activated carbon is packed inside each filter cartridge to remove odor, discoloration, and water impurities. Maximum water-to-carbon contact is obtain via the patented ribbed back of each filter cartridge. Plus, fill the included refillable four ounce media container* (two in the 400; one in the 280) with your favorite course media for added chemical filtration.
  3. Biological Filtration - the most critical kind of aquarium filtration is obtained by the large, patented BIO-Wheel (two in the 400; one in the 280), which encourages the growth of beneficial, oxygen-breathing bacteria. This bacteria helps eliminate toxic ammonia and nitrite that accumulate in aquarium water. The bacteria culture biologically changes the ammonia and nitrite into nitrate, which is then removed with monthly partial water changes. The patented BIO-Wheel is the undisputed best power filter when it comes to biological filtration. BIO-Wheel is scientifically proven to be better than frames, foams, fluidized beds, under-gravel filters, and other submerged biomedia.
    * NOTE: Fine media must be placed in a mesh bag inside of the refillable media container to avoid leakage into your aquarium system.

Adjustable Filter Regulators:

  1. Spray Bar Drive - simple, twist-adjust bar regulates BIO-Wheel rotation speed for maximum biological filtration. Controlling the amount of BIO-Wheel spin ensures the beneficial bacteria that grows on each pleat of the BIO-Wheel get adequate contact with both the aquarium water and the surrounding air/atmosphere. It also controls how fast or slow the filter pulls water out of the tank and through the three-stage filtration process.
  2. Intake Tube Extension - designed to easily slip-on to the Intake Tube for the filtering of water from deep within a larger tank. With this extension in place, the filter strainer is located nearer to the gravel line of your tank to pull water ripe with settling debris and fish and food waste. Plus, having water that is pulled from the bottom of the tank, ran through the multi-stage filter, and returned to the top water level of the tank creates the necessary, natural cycling of water beneficial to both your aquarium plants and animals.
  3. Mid-Level Intake Strainer - also designed to easily slip-on to, and act as a coupler between, the Intake Tube and Intake Extension Tube. This mid-level strainer ensures mid and high-level water quality isn't sacrificed when the Strainer is attached to the Intake Extension Tube and set deep in a larger tank. The Mid-Level Strainer features a notched flow-adjustment valve to both regulate intake flow and let water near the top of the tank also enter the multi-stage filter process. Filtering water from the higher levels of the tank - where medications, food particles, and descending debris - is good tank husbandry. Plus, by allowing water from all tank levels access to the multi-stage filtering process at the same time, the BIO-Wheel filter aids in the natural mixing of tank water. This water mixing is essential to good water quality that helps regulate water temperature and oxygenation levels, while also preventing the "pooling" of high toxin levels and chemical tank maintenance additives within one level of the tank.
  4. Media Containers and Filter Cartridge Expansion Slots - pre-formed slots throughout the filter chambers (four in the 400; two in the 280) allow you to add as little or as much mechanical and chemical filtration as needed to suit your specific tank. Plus, each included media container (the 400 includes two; the 280 includes one) holds 4 ounces of your preferred course media to target the removal of specific high-level chemical toxins or nutrients within your tank.

Easy-Access Maintenance and Cleaning:

  1. Hang-on Design - the molded heavy-duty plastic housing rests on the back wall of your tank to meld optimal, multi-stage filtration with easy access for maintenance and cleaning.
  2. Slip-out Spray Bars - sturdy plastic clips on the outside edges of the filter housing allow easy removal of the Spray Bars with minimal contact to and disruption of the BIO-Wheel and/or filter media(s). Included FREE cylindrical cleaning brush is perfectly designed to slip inside each Spray Bar, as well as the Intake Tube, for monthly cleaning.
  3. Hinged Filter Chamber Cover - durable plastic cover features a hinged top design. This allows you to simply and periodically check the BIO-Wheel(s) to ensure proper bacteria growth and function without disrupting the filter process or accidentally bumping the tank when removing a bulky cover. Plus, when cleaning the tank, the snap-on cover also easily removes, permitting full access to the filter chamber, filter cartridge(s), and media.
  4. Tension-Tab Closure Media Containers - the included media container(s) (the 400 includes two; the 280 includes one) features tension-tab closures that allow you to easily open each container to fill and secure your chosen filter media.


Emperor 400 Review

For the last decade (or more) you could not have a discussion pertaining to the “Best HOB Filter” without two specific filters rising to the top, the Marineland Emperor 400 and the Aquaclear 110. Man, have times changed. While such a discussion must still consider the Emperor 400, it can no longer compete with the Aquaclear if the subject of noise levels is included. Since “noise” has a direct correlation to quality, the longevity of the newer Emperor filters must also be questioned.

Marineland is a shell of its former self, run to the ground by United Pet Group who has turned it into an offshoot of Tetra. The newer models of Emperor 400s reflect the change in philosophy resulting from United Pet Group leadership, quantity over quality. As a result, the Emperor 400 now sells based upon its former reputation, which is no longer as well deserved.

I have owned Marineland Bio-Wheel filters since the early 1990s. I have observed a decline in the quality of these filters over the years with a very sharp decline occurring around the 2008-2009 time frame. The filters look the same, they just do not run the same and they certainly do not sound the same. The two most recently purchased Marineland HOBs I own happen to be the loudest HOBs I own, with one of those being an Emperor 400.

I don’t want to come off as completely negative. The Emperor 400 remains a viable option. It’s not as if the decline in quality that is affecting this filter is not a universal problem. Basically, All manufacturing of All filters now occurs in China so the quality of All filters is suspect. The days of “make the best product and people will buy it” are gone, replaced by the “make the cheapest product and people will buy it”. Unfortunately, we, as consumers, support this change in philosophy so we deserve what we get. This is why the Emperor 400 remains a viable option. It is so much less expensive than it’s only (true) competitor, the AC 110. I purchased my Marineland 400 for $39, which is a great price on these filters. The competing Aquaclear is $89 (can be found on sale for $69). Still the Emperor is much less expensive. So if you can handle the noise, it is a better option because in reality, as a biological filter, it remains superior to the Aquaclear design.

Nor do I want to over emphasis the noise levels. If you want absolute silence, you do not need to be using HOB filters. When I first hooked up my Emperor 400, it rattled and hummed like U2 in 1998. 24 hours later, the rattle was gone, only the hum remains. It certainly is not as quite as its 2005 and prior version (versions with flow control knobs) but nor is it at jet engine levels. However, if you are in the same room with this filter, you will be aware that it is running.

EDIT: Several months after authoring this review, the filter has become somewhat quieter. It has reached the "bearable" stage. A hum remains and you will be aware of the filter if you are in the same room with it, but it is no longer nearly as obnoxious.

It is also an impressive filter. Open the box, pull it out, and the size of the filter will surprise you. The “water wells” are very deep for an HOB which allows for very large mechanical surface area of the cartridges. It also utilizes a much larger Biowheel than the Penguin line.

  • As a primary filter for those that simply do not want to go with a canister filter, it remains a viable option, potentially even preferred over the Aquaclear line (because it is a better bio-filter). Just be prepared to handle the noise.
  • As a secondary filter to be used in conjunction with a canister filter it remains a viable option, potentially even preferred over the Aquaclear line (because of costs). Just be prepared to handle the noise.

If "design" is the primary focus of the discussion of "Best HOB", the Emperor 400 wins, hands down. If you include noise and noise as an indicator of quality, it does not. 


  • Outstanding Biomedia Capacity – Best biofiltration capability of any HOB.
  • Large Biowheels– The inherent dynamics of HOB filters makes them undesirable as biological filters. Biowheels eliminate this concern. They are the only method of biofiltration where flow rate is more important than surface area.
  • Large Media Containers– Each Emperor 400 ships with two media containers. If using the Emperor 400 as primary filters, you should fill these containers with Eheim Ehfilav, Eheim Substrate Pro, or some similar (smaller sized) biomedia, to extend the bio-capacity. Combined, these two containers will easily hold more biomedia than can be included in an AquaClear filter, then you have the added biofiltration capacity of the biowheels.
  • Large Mechanical Surface Area– Mechanical filtration effectiveness is determined by surface volume (length x width) and flow rates. Combined, the two cartridges provide more mechanical surface area than other HOBs, including the AquaClear line. If using as a secondary filter optimized for mechanical filtration, you can include 4 cartridges (see “Suggested Modifications” below.)
  • Impressive Flow Rate– At 400gph, only the AquaClear 110 surpasses it. However, as it relates to biofiltration, the higher flow rate on the AquaClear 110 is pretty much wasted whereas it is not on the Emperor 400. As it relates to mechanical filtration, as mentioned, flow rate plays a significant role. Since the flow rate of the Emperor 400 is higher than most canisters, it can easily be optimized to become the primary mechanical filter on a tank (see “Suggested Modifications” below).
  • Marineland Customer Service– While manufacturing has moved overseas, Marineland Customer Service has not. They remain amongst the best.
  • Cost – A high end capacity filter at a reasonable cost.


  • Frigging Noise- Come on Marineland/Tetra/United Pet Group. Do something about it.
  • Quality - As far as materials used in construction of the casing, the Emperor 400 is an improvement over the Penguins. However, noise is an indication of quality construction, and the Emperor 400 fails here.
  • Tube length - In order to use the shipped tubing or mid -level strainer in a 55 gallon tank, it would have to be cut. Otherwise, you just connect the strainer to the first level of tubing, which means it is not at the optimal depth for mechanical filtration.

Emperor 400 Modifications:

I don't use the manufacturer cartridges. Instead, I use Bio3 Emperor Filter Cartridges, only using the clamshell and blue sponge, setting the carbon pads aside, and using blue bonded padding cut to fit. If optimizing your Emperor 400 for mechanical filtration, you want to use 4 of these customize cartridges.

Posted: 3 years 9 months ago by Astronotus6 #48768
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like someone else stated, the bio-wheel on my emperor would always stop moving & a bit noisy.
Posted: 3 years 9 months ago by MikeB #48761
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Posted: 3 years 9 months ago by kmuda #48760
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I use AC 70s on my water aging tanks because it's easier to remove and replace media such as Peat and Carbon. But on my tanks with fish I use Emperors and Penguins, because it's easier to clean or replace mechanical media.

I simply cannot justify the increased cost of an AC110 over an Emperor 400. If I am going to spend that much on. Filter it's going to be a canister.
Posted: 3 years 9 months ago by MikeB #48750
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Same here I have emperor 400's , I like them and fill the grey plastic cases with blue filter pad cut to fit and use foam pads for my fluval ( generic pads from amazon) in front of the grey case as extra filter . It works well, they were loud at first but have since gotten much quieter over time. I'll keep them till they go out , then try the AC or penguin.
Posted: 3 years 9 months ago by MarshyMellowFluff #48707
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Maybe if one of my emperors breaks down I'll try one, I see lots of people have them with oscars.
Posted: 3 years 9 months ago by Astronotus6 #48703
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I've also had both Emperor 400 and 2 AC 70's... I like the AC much better. (quieter, easier to maintain, better quality) IMO.
Posted: 3 years 9 months ago by MarshyMellowFluff #48698
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Emperor 400's uses to be $40. In Canada they went up to $80, I don't know when or if its increased in price anywhere else, but man does it suck. I had them running on my 125 for two years with no issues, so i decided to buy another one for my 55 and it was $80.. crazy.
Posted: 4 years 9 months ago by FreshyFesh #13528
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Oh that is VERY cool. I didn't know those re-usable filter clamshells existed. Definitely makes a cartridge HOB way more attractive.
Posted: 4 years 9 months ago by kmuda #13519
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Imagine makes the clamshell cartridges that fit Emperor, Penguin, and Whisper filters. So it's less DIY than it is adopting something designed to fit. I use the blue sponges that come with the clamshell cartridge and only diy the blue bonded and micron pads, cutting them to fit the clamshell. I am able to run four of these in and Emperor 400 or Penguin 350. Two in a Penguin or Emperor 250. The fit just like the stock cartridges.
Posted: 4 years 9 months ago by FreshyFesh #13516
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There's some good options for DIY media for sure. I know the problem I've run into with my somewhat recent (non AquaClear) HOBs purchases was they were smaller HOBs, and trying to retrofit them with DIY was difficult because of the small size of the filter housing. Stuffing anything other than the OEM cartridge in there would totally change the flow path of the water being filtered.
Posted: 4 years 9 months ago by kmuda #13513
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Imagine 3 clamshell and sponges combined with blue bonded padding and 100 micron padding cut to fit. I have not bought any additional media in 3 or 4 years. But you are right. If you are buying the Marineland Rite-Size cartridges, you will quickly exceed the ACs cost.
Posted: 4 years 9 months ago by FreshyFesh #13511
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True about the price, but if you factor in the cost of replacement filter cartridges, you will meet/exceed the cost of a comparable AC at some point. If you make your own mechanical media, it's all good.
Posted: 4 years 9 months ago by kmuda #13510
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Don't get me wrong. I am not touting an Emperor over a AC110. If you read the review you will see I was not overly positive on the Emperor. What I am saying is that the Emperor is a better bio filter than the AC110. If I was going to rely on an HOB filter as my sole source of biofiltration I would select an Emperor.

But fact of the matter is that I don't rely on an HOB for biofiltration. Even my small tanks have an Eye I'm 2213 on them. An HOBS primary function should be to offload mechanical filtration from the canisters in an easy to access location allowing for weekly quick cleaning..... removal of the stuff before it breaks down into nitrate while feeding bacteria you would rather not have in the tank. To accomplish this, the HOB should have the highest flow rate of any filter on the tank. By default, the highest flow filter will be the primary mechanical filter. The AC110 fits this requirement better than any other HOB.

I just have a hard time paying between $60 and $90 for an AC110 when I can get a filter that does this job, when properly outfitted, almost as well for between $40 and $60.

Freshyfresh.... that is a shortcoming of any biowheel filter. In hard water the wheels will calcium and stop spinning. My water is very soft. I've had wheels spin continuously for.20+ years. Albeit that is on the old original Penguin filters. Completely different animals. You could throw them off.of a roof and they would bounce, go right back on the tank and work. this brittle plastic ones made today..Although even with the new ones, I have not had an issue with the wheels siezing. But again, I have soft water.
Posted: 4 years 9 months ago by FreshyFesh #13507
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I didn't care for the small Penguin bio-wheel I had. Couldn't keep the wheel spinning after multiple spindle/receiver cleanings. Also don't care for filter cartridges in general. I know you can make your own to an extent, but there's nothing easier than AC's and their sponges IMO. Pretty much have had all your common HOBs at this point. First was a DynaFlow (sp?) back in the 1980's. They had an actual fan-cooled electric motor that spun a metal platter that got the impeller magnet spinning. Memories.. good times.
Posted: 4 years 9 months ago by popss #13488
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agreed, but I will take the sponge and matrix in the ac over the bio wheels with panels any day.
Posted: 4 years 9 months ago by kmuda #13471
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popss wrote:
Kmuda you killen me, i have a marineland on the 180, the duel wheel 150. no where near the AC110 for bio filtration.

I assume your concept is based upon available surface area?

Two things you have to keep in mind. 1st is that with standard filter media (sponge, rings, etc....) flow rate in excess of around 270gph becomes a detriment to biofiltration. This is sound filtration dynamic principle. The water has to stay in contact with the media long enough for the autottrophic bacteria to oxidized the ammonia. In high flow rate systems, you compensate for this by increasing bed depth.. It's a complicated concept.I don't want top thumb tap on my phone. You can read more about it in my bacteria articles in the articles section, especially the article where I dispute the "bacteria populations only grow to the size of the amount of ammonia being produced" belief. Regardless, let me clarify the "increase bed depth".statement. Think Eheim 2262. A monster filter with massive media capacity. You simply are not to achieve the necessary bed depth in an HOB.

So, the 1st basic concept is that, while high flow rates are beneficial to mechanical filtration, they are detrimental to biofiltration.

The 2nd concept is that this all goes out the window with biowheels. When it comes to HOB filters, biowheels are the only type of media where surface area and bed depth are irrelevent. Where flow rates in excess of 270gph can become beneficial to biofiltration. Autotrophic bacteria become more efficient at higher oxygen concentrations and higher PH. Regardless.of.surface movement in your tsnks, the highest O2 saturation you'll achieve is 9ppm. Nowhere near what is available in the atmosphere, where biowheel bacteria get their oxygen from. Think of it as biowheel bacteria run on rocket.fuel while submerged bacteria run on diesel.

So a single autotrophic bacteria on a biowheel is able to.oxidize significantly.more ammonia, faster than bacteria on submerged media. This tosses out both limited surface area and high flow rates as biofiltration.

Since all hobs have limited surface areas and the two in discussion have high flow rates, if selecting an HOB as my primary filter, I would select the one where the biofiltration limits of all HOBs, based upon the principles of filtration dynamics, are the least concerning. A filter not impacted by high flow rates and limited surface area. Which would be the Emperor 400.

At.least those are the concepts that go into me identifying the Emperor 400 as the better biofilter.

I'm sure there are a ton of fat thumb typos in this post. Hopefully it still makes sense.
Posted: 4 years 9 months ago by JAJameson2010 #13469
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Thanks! This is an extensive review! I was planning on buying the aquaclear. But if this is half the price, I'll try it out. It's not going in the bedroom and BF has this annoying habit where the TV has to be on all the time! So noise isn't really an issue for us. Plus of its annoying it will motivate me to switch to a canister quicker.
Posted: 4 years 9 months ago by popss #13467
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Kmuda you killen me, i have a marineland on the 180, the duel wheel 150. no where near the AC110 for bio filtration.
Posted: 4 years 9 months ago by kylestivers33 #13464
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Total piece of junk do not waste your money the only marineland filters that are good are the c series canister filters all other marineland filters are junk. It is so dam loud sounds like a grinder running.