Aquarium Filter ( Filtration System for Fish Tanks )

An aquarium filter is one of the critical fish tank equipment.   Everyone must have it to run a home aquarium without fish dropping like flies. A fish will not survive for long in a fish tank without filtration system running 24/7. Simply put, please do not get any pet fish at all if you do not plan to install an aquarium filter.

What is an aquarium filter for? Why do we need it?

There are three primary functions for an aquarium filter system in a fish tank.
1. Biological filtration
The most important and absolutely necessary function of an aquarium filter system is for biological filtration. To sum it up, biological filtration in an aquarium is the process of converting the toxic ammonia produced by fish to relatively harmless nitrate. Without biological filtration, no fish can survive in a closed system such as in a home aquarium for long. To understand it further, you must first understand Aquarium Nitrogen Cycle which is one of the most critical knowledge every fish hobbyist must learn.

2. Mechanical filtration
Mechanical filtration is to remove debris such as fish waste, leftover fish food, and other debris from the fish tank water.

3. Chemical filtration
Depending on what filter media you have in your filter, aquarium filters with activated carbon pads are capable of removing certain dissolved chemicals from the water.

Contrary to the common belief, the primary function of an aquarium filter system is not for the traditional sense of “cleaning.” Although mechanical filtration is part of the features of many types of aquarium filters, the primary function of an aquarium filter is (not) to get rid of fish waste or other debris in the tank water. The reason is simple, even if the aquarium filter has removed the debris such as fish poop and leftover fish food, it has only removed it from your sight. The fish waste and fish food inside the filter is still polluting the water of the tank.  Because the tank water is cycling through it every second.

Thus, it is pointless to depend on the aquarium filter to remove fish waste and other debris from your fish tank. On a side note: To truly remove the debris from your fish tank, you should use an aquarium vacuum.

Chemical filtration is often for removing bad smell from the fish tank water. However, any well maintained healthy aquarium should not have a bad smell at all, to begin with. Activated carbon can’t absorb an unlimited amount of chemicals. Thus it is only a temporary fix rather than a sustainable solution. Most experienced fish hobbyists do not use activated carbon pads at all in their aquarium filters because it serves no purpose unless they want to remove the medication from the water column in the case when they have just treated the fish for some diseases or parasites.

That leaves only biological filtration as the primary purpose of the aquarium filter system. Without it, fish will die due to ammonia poisoning. Once again, if you have not read the article of Aquarium Nitrogen Cycle, we highly recommend that you read it to get a full understanding of biological filtration in an aquarium.

Important Note: Since all fish produce ammonia on a constant basis, the aquarium filter system must be running at all times to keep ammonia at zero. Daily water change is no substitute for an aquarium filter system. You will still need a filter even if you do water change multiple times a day. Do not skip the filter system when you set up a fish tank.  Never turn the filter off when you have fish (aside the little time you spend on fish tank maintenance). An aquarium filter is as important as the fish tank itself. Neither should be there without the other one.

Now you know the importance of an aquarium filter system for a fish tank. There are so many different types of aquarium filters out there. Which filter should you use? To choose a filter system, you must first understand the different types of filter systems.

Different Types of Aquarium Filters:
1. Power Filters
These filters are often hanging on the back of the fish tank.  They create a waterfall as the water runs through them. Power filters are relatively cheap, and they are the most commonly used filters for this very reason. They also have downsides, which include the noises (waterfall, as well as the motor). The intake and outflow of most power filters are relatively close to each other, which makes the intake continue to take in a lot of water which was just filtered.

Power filters also have limited filter media, which makes biological filtration a less strong point. While it might be a good choice for small- to medium-sized fish tanks, personally I would not recommend a power filter for anything more than a 30 gallon (or 110~120L).  Nor a tank with a heavy stock of fish. You may, however, use two or more power filters for a single large fish tank, but it defeats the strong point of being cheap. AquaClear power filter is one of the best power filters available.

2. Internal Filters
Internal filters are placed under the water in a fish tank. Thus they are also called Underwater Filters. They take space inside the tank. While they do fine for both biological and physical filtration, they are usually for small- to medium-sized fish tanks.

3. Canister Filters
This is the very high end of aquarium filter system. They appear to be in the form of a large canister. The whole filter is usually below the fish tank.  Only its intake and outflow tubes are visible inside the tank. Canister filters are extremely quiet. For example, I have an EHEIM Classic 2213 Canister Filter, and I can’t even hear anything at all without putting my ear directly against it. Canister filters also hold a significant amount of filter media, which means they are the most efficient filters for biological filtration. Place the intake and the outflow tubes on the opposite sides of the tank.  It solved the issue of the weakness of a typical power filter.

Canister filters are highly efficient, but they are not cheap. There is no need to get one unless your tank is at least 30~40 gallon (110~150L). I might be biased. It is my favorite type of filter system because of its high efficiency and 0 noise level.

4. Wet/Dry Filters
It is another high-end form of aquarium filter system designed for large aquariums. Wet/Dry Filter is the preferred filter system for many saltwater aquarium hobbyists.

5. Sponge Filters
This type of aquarium filters is the simplest form of filters, and thus the cheapest. Unlike other filters which have their little motor to pump the water through the filter media, you will need a water pump or air pump to power a sponge filter. Sponge filter itself is nothing more than a piece of sponge on the top of a few other parts including a tube and an air stone (although usually, you have to get the air stone separately yourself).

A sponge filter can run independently.  It can be the pre-filter on the intake of power filter or canister filter to increase biological filtration as well as pre-filtering debris to decrease the maintenance requirement for other more complex filters. The sponge filter is perfect for low budget aquariums. Unlike other types of filters, a sponge filter will not suck anything into it, thus making it perfectly safe for small fish fry and shrimp. It is the ideal filter for breeding or fish fry tank.

The negative aspects of a sponge filter are: it takes extra space inside your tank, and it might not be pretty “decoration” inside your tank.

While it is not as efficient as a canister filter, multiple large sponge filters powered by a single air pump with split valve should be good enough for even a large aquarium of any size. It is also a perfect solution for those hobbyists who run many fish tanks on a limited budget. You do not have to buy expensive filters for every one of your fish tanks. Just one cheap sponge filter per tank hooked up to one or a few air pumps will meet all your biological filtration needs.

My favorite sponge filter is Hydro Sponge Filter. Three out of four of my smaller fish tanks have them running for years without a problem. If you decide to go for sponge filters, make sure you also have an aquarium air pump, air tubing, and air stone to power it.

Which types of aquarium filter should you choose for your fish tank?

To choose an aquarium filter system, you should look at two things.

1. Recommended fish tank size
It is the tank size recommended by the manufacturer to use with their filters. Note that most of them say “up to 20 gallons” or “up to 30 gallons”. It is the maximal size of tank the manufacturers say you can use their filter.

A heavily stocked tank with more or bigger fish requires more filtration than a lightly stocked tank of the same size. This “up to” is most likely for the cases when the tank has a heavy stock. You should always go one step up on this rating unless your tank indeed has light stock.

2. GPH (or Gallon Per Hour)
This is the flow rate of the water. The faster the water goes through the aquarium filter, the more efficient the biological filtration is. If you are using a power filter, the recommended GPH should be able to go through your entire tank water 5~7 times per hour.

Canister filters are on a different level because they have a lot more filter media in them.  They should be fine with just enough power to go through all of your tank water three times per hour.

GPH on most aquarium filters is rated with an empty filter without filter media in there. Once a filter is filled with filter media, the actual GPH should be a lot lower. One exception is EHEIM, a reputable German brand. The GPH on their filters is rated with a full set of filter media. My EHEIM classic 2213 canister filter has been working in a heavily stocked 40-gallon aquarium flawlessly for years.

Whatever aquarium filter you choose for your fish tank, it should be efficient enough. An underpowered filter will not provide enough biological filtration.  As a result, there will still be ammonia in the water, which will defeat the purpose of having a filter. With a very efficient filter doing its job, the only maintenance you need is weekly partial water change. You may install multiple filters in the same fish tank.  Or you may get a filter which is rated way higher than your fish tank size. You can never have too much filtration. With the exception that water current is too strong for the fish, more filtration is always better.

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79 thoughts on “Aquarium Filter ( Filtration System for Fish Tanks )

  1. Pingback: Aquarium Maintenance (How to clean a Fish Tank) - Pets Keepers Guide

  2. I recently bought a 20g aquarium along with ornaments (2 weeks) back. I started fishless cycling with pure Ammonia (Goldex – from Walmart). I am ok with the results up until now. I have 1 power filter (Marineland-150gph) and a whisper air pump with 1 air stone which runs 24×7. I know that I may have to wait for 4-6 more weeks before adding fish.
    However, I feel that adding a Eheim canister 2213 could help more with my water filtration – could you advice on it?
    Would the canister be disturbing the fish with it’s strong force? Or would it have any damaging results for a 20 gallon aquarium?

    • EHEIM Classic 2213 is rated for fish tanks bigger than 20 gallon. Fortunately, there are valves on the intake and outflow tubes for you to adjust the flow rate. The spray bar comes with the filter can also be used to slow down the current. You can also add a piece of sponge filter as pre-filter on the intake of the canister filter to further slow down the water flow.

  3. Hi , this is a good help for starters
    i have a question , i am planning to set up a freshwater aquarium of size 50~70 gallons , but i live in iraq and i cant find any canister or power filters in the city where i live, but there are chinese internal filters 1800L/h , 1200L/h , ….. , can i still use them for my aquarium of size 50~70 gallons ?
    another problem is that we will have electricity cutoffs without prior warnings in random days for may be 10 hours or even more each time , i heard that if i use power filters or canister filter bacteria will die if the filter is turned off ? do that makes internal filter a better choice for me ?
    what is your advice ? what should i do ?
    btw thnx 🙂

    • Hi Arman,
      For the first part of your question, the internal filters will work as long as the (gallon per hour) meet the minimal requirement for your tank size. Keep in mind that don’t choose too high models either, since too much water current might bother some slow moving fish.

      I see you have the random power outage problem, I believe internal filters will work better than power filters and canister filters in your case. The worst choice would be power filters, since they will lose the good bacteria in there in the case of a power outage. Although the canister filter will not lose the bacteria (the canister will still have water in there during an power outage), it won’t do your fish tank any good once it stops running the water through it.

      You might also want to consider a sponge filter. The whole piece of sponge stays inside your aquarium, so whether it is powered or not, the good bacteria on there will be converting ammonia and nitrite. (faster water current through the sponger filter will increase the converting rate, but no water current won’t cut the converting rate to zero either).

  4. I bought a 30gallon tank and i am completely clueless on what to do. I hqve a very low budget but from whatvi read im thinking of getting a a power filter but dont inderstand the gph on a 30 gall. Help

    • Hello Yanet,
      For power filters, it is recommended to have a filter powerful enough to go through all of the tank water 5~7 times each hour. So for a 30 gallon fish tank, you need a filter with GPH (Gallon Per Hour) of 150 to 210.

      If you have any further questions, please ask us on the forum.
      Good luck!

  5. I bought a 20 gallon long aquarium and looking for the best filter set-up. I’m thinking of either two AquaClear 20, one in each corner, or one AquaClear 50 in the middle. What do you recommend and why? Thanks!

      • For an aquarium of 20 gallon, around 20 or so Tetras should be considered as “fully stocked”. Nope, I am not using the “inch per gallon rule” as it is flawed 🙂 Overstock your fish tank can cause ammonia spike. Most Tetra are very active, they need swimming space. I hope your “as many as I can” really mean as many as the tank allow without overstocking. 😉

    • AquaClear 50 might be overkill for a 20 gallon tank in my opinion. It has a gallon per hour rate of up to 200, which could mean too much current for your 20-gallon tank. An AquaClear 30 (with 150 GPH) could be a better option. Two AquaClear 20 can work too. Much larger tanks might be able to take advantage of two filters. A single AquaClear 30 should work just fine for a tank of your size.

  6. OK I need help. I have a 20H And have the recommended size power filter. I want to eliminate visible filters because I am putting up a Christmas moss wall on back. Have 12 guppies, 2 clown plecos, 3 Cory cats, 10 shrimp, and 3 tetras. Any suggestions on what I need. Thought about under gravel filter, but heard they are not good. Thank you for any help received

  7. My adjustable power filter (API Superclean 5-20) for my 5 gallon tank has a carbon prefilter and bio-chem stars for growing the tank’s beneficial bacteria. Just now in beginning stages of fishless cycling.
    If carbon filters are unnecessary, do you recommend replacing it with a sponge filter to remove debris and act as an additional site for bacteria?
    Also, hoping the lowest setting will be acceptable to my betta. Any suggestions for baffling the surface current without compromising the filter function?

    • More filter media (sponge for example) means more filtration, and it is a good thing to have for an aquarium. Yes, one extra sponge pad will increase total surface area in the filter media for the bacteria to colonize on. If you are concerned with strong current, you can add an extra sponge filter as pre-filter to the intake of your power filter to slow down the current. If you have any more questions, feel free to use our forum. It is easier to go back and forth there. 🙂

  8. I am setting up a 35g which will house some average bioload tropical community fish. It won’t be overstocked or anything. However I don’t really want to spend too much on a filter. What would you recommend? I only have experience with a sponge filter. Do you think a large sponge filter could be sufficient? Many people said it is fine to use but others disagree. What is your opinion?

    • It depends on the rated gallon for the filter. It is usually a good idea to go one step above the manufacturer rated gallon. I’d go with two sponge filters (one on each side) if I were you. Yes, it is the cheapest option for filters.

  9. So my filter broke. and I have a 10gallon tank with 2 goldfish in it. I sent my sister (which was a big mistake) to get me a new filter while I was at work. She got me a Whisper EX 30 which is made for 20-30 gallon tanks would it be okay to put on my 10 gallon or should I return it?

    • I think your problem is more than just the filter.
      A 10 gallon tank is way too small for two goldfish. Minimal size required for two fancy goldfish is 30 gallon, and it goes up to 55 gallon if they are common goldfish. Goldfish are high polluters since they eat a lot and produce tons of waste. Insufficient tank size and filter will not keep the water free from toxic such as ammonia and nitrite.

      The possible problem with running a filter rated at 20~30 gallon on a 10 gallon tank is too strong of water current. Fish might not like it and it is tiresome for slow moving fish like goldfish.

      I highly recommend you to get a bigger fish tank. If you have any more questions, feel free to post away on our forum.

  10. I have got a 15 gal tank and i want to setup a freshwater aquarium. I need recommendation reguarding the filter i should use and the number of fish i should stock. Thanks 🙂

    • Hi there,
      A tank size of 15 gallon should use a power filter. Just pick an Aquaclear power filter with manufacturer rated at around 20~30 gallon should be fine. As for fish, it is the best to get no more than 5~10 small sized (less than or around 2″ long at full adult size) fish. You are welcomed to post away on our forum if you have any more question. 🙂

  11. Hi i am buying 35 gallon tank,can u tell me what will be the best filter for this aquarium,price doesn’t matter.tnx alot 😀

      • Hi Julian,
        We have another article about how often to change the aquarium water.
        But anyway, usually we do weekly partial water change of 30~50% as a part of regular aquarium maintenance.

        Feel free to post questions on the forum. 🙂

    • Either a power filter to hang on the side, or a canister filter of low tank size rated. I prefer canister filter, since they are more efficient, quiet, and low maintenance need.

  12. Hi, your article has been extremely helpful! I have a 29 gallon tank that has been running for over a year and a half and is fully cycled. I have sailfin molly fish, tetras, corry catfish,and african dwarf frogs. Right now i have a filter made for a 30 gallon tank, but I think its too small. My tank is currently a little overstocked, because I unknowingly bought a male sailfin molly with my females and of course they mated, and i now have offspring that I’m currently trying to give away. Do you think that getting the Aqueon QuietFlow 50 power filter is too big? I know I need more than a 30 gallon filter, but I’m just worried that the current will be too strong. My dwarf frogs swim to the top of the water and stay on plants by the surface. I read how you replied to someone about sponges to slow down the current, but I didn’t understand what you meant. Thank you so much for this article and your time!

    • Oh, and if you don’t think the filter that I listed is good, can you please suggest something else for me. I don’t really know much about filters and I’m definitely open to any suggestions.

      Once again, thank you!

      • Anything from Aquaclear, EHEIM, Rena, Fluval are good in my opinion. Just get the right size for your tank. All manufactures have rated their filters based on the adequate tank size they are made for. A part of the equation was the water flow in gallon per hour. Amongst them, EHEIM is the most efficient due to their flow rate is based on fully stocked with filter media while all other manufacturers use empty filter for water flow test.

    • You can slow the current by install a piece of sponge filter on the intake. By doing this, it will also increase the filtration. Check local pet stores or online for sponge filters. It would be a lot easier to answer your questions with photos. Come to our forum to post your questions. 🙂

  13. Oh, and how do I prevent my tank from starting a new cycle when I replace the filter? This is my last question; I promise!

    • You can install the new filter first, to let it run along side of the old filter for minimal 3 weeks. The longer the better. To allow the new filter have the time to establish a new bacteria colony before remove the old filter from your aquarium.

      We welcome questions. Feel free to post away on our forums if you have any thought or question. 🙂

  14. just bought a 30 gal half moon tall, (used)
    i have always had smaller tanks, i do freshwater, mainly all different types of golds.
    i need “GOOD” but low cost, filtration (under $100.) that is a low maintenance, sturdy and longevity.
    i have always had the over the back power filters, but with the tall tank i don’t know how efficient those would be.
    i do have a reverse osmosis (under the sink type,filter) and am wondering if i could possibly (and how) to hook that up to the tank to run it

    • If your budget is $100 or less, than you can get a canister filter. I recommended EHEIM 2213, and it is only around $80. It is a lot more capable than power filters of the same manufacturer rated tank size. If you install a small piece of sponge filter on the intake, it will cut down the maintenance of the filter to once every a few months.

      Do (not) use RO water directly for an aquarium. It has zero buffer in which case the water PH can easily crash and it can be a big problem for the fish who like stable water conditions.

      Feel free to use our forum for any further questions. 🙂

  15. Is it okay to run a 40 gallon filter in a 50 gallon tank? I only have one fish a flowerhorn. I’ve been running it for a few days and the water is turning cloudy and green. I changed 80% of the tank and it looks like it’s turning green again.

    Any advice?

    • Hi Lisa,
      It is ok to use a slightly underrated filter as long as you do not overstock your aquarium with too many fish.
      The cloudy and green water might be caused by several things. Overfeeding, exposure to sunlight or too much lights, and not enough regular partial water change. Cut back on feeding will solve most of the problem of cloudy water, and the green water you see is an algae boom which is a direct result of too much light exposure as well as too much organic waste in the water.
      If you have any future questions, feel free to use our forum for easier chatting. 🙂

  16. i have a 35 gallon tank, a 25 gallon tank, and a 10 gallon tank. i often have issues with cloudiness. i have been debating on a filter with uv sterilization, however i have smaller fish including minnows and tetras and most of my fish are not strong swimming. how many gallons per hour should i look for that will effectively clean my auarium but not kill my fish as i have already lost fish due to them getting stuck in the path of too strong of filter suction

    • The effectiveness of filter is not just depended on the gallon per hour. It has to do with the amount of filter media in the filter. That is why canister filter is the most effective filter of all due to the fact it has the most filter media. If you use a power filter, you should be look at enough GPH for the filter to go through all of the tank water 3 to 5 times every hour. For canister filter, 2~3 times per hour is enough.

      On the other note, cloud water is mostly caused by bacteria boom which means there is either not enough good bacteria colony in the filter yet, or there is too much organic waste in the system caused by either overfeeding or too many fish. You should be cut back on feeding to see if the problem go away on its own.

  17. this may sound stupid but i keep finding my guppies in the suction of my filter can it be too strong for my tank or are they to weak from something else killing them or are they too weak and get caught in the suction because some have been still alive but die latter

    • Your filter might be too strong for your fish. You can install a piece of sponge as pre-filter on the intake to prevent any fish being sucked in.

  18. Hi. I am planning to get a new 20 gallon tank as a breeder tank for feeder guppies. Which filter is best for the future fry and cycles the fastest? And also is there any way to make sure ur tank is cycled without using test strips? Thanks ^_^

    • For a fry tank, sponge filter is the best sick there is no risk of suck in the small fry. As for which filter cycle the fastest, the filter type has nothing to do with the time required for cycling. Without a water test kit, there is no way to make sure your aquarium is cycled. API freshwater master kit is only for about $20 from various stores including Amazon. There is enough liquid in there for more than 200 tests. I think it is a good deal.

  19. Im getting a 55g tank tomorrow but am not going to set it up yet since i dont have a filter or anything for it. What filter would you suggest for it? It will be a freshwater tank. Could I use 2 of the smaller hob filters or should i just go ahead and find a canister filter? What brands would you suggest?

    • My recommendation would be a canister filter from EHEIM. However, two AquaClear Power filters will do fine too. It is really up to you. Canisters are usually the most efficient and also very quiet.

  20. I have a question about my 20 gallon (L) aquarium. I currently am using a bio wheel filter HOB. I’ve purchased a duel sponge filter Because I wanna add shrimp to my awe. It says it’s made for up to 20 gallons but is it really powerful enough to be the only filter in the aquarium

    • Is your sponge filter powered by an air pump? As long as you position the filter well and the air pump is strong enough, then it should be enough for your tank.

  21. Hi.. I have build my own Aquarium of capacity 50 galons and i am looking for a best filter. Which filter should i choose between top filter and hanging filter?

    • For a fish tank size of 50 gallon, I would recommend a canister filter if budget is not an issue for you. EHEIM makes great canister filters. I have used their classic serious for years without a problem. You may get newer models if you are willing to spend more. The newer ones are easier to clean.

  22. Hi.
    Thanks for such wonderful article.
    I live in not so advanced city in india. I am planning to get a tank of about 40 G. I can manage something expensive but I don’t to spend unnecessarily. Please suggest me filter system and some good fish combination. I don’t want to overstock tank. As I am totally new in this, any suggestions you think will be good for me are welcome.

    Thanks a lot.

    • Your cheapest opinion would be getting a sponge filter and hook it up to your air pump. The next cheapest opinion would be a power filter. Make sure what you purchase should be rated higher than the tank size to get enough filtration.

  23. Help! I bought a 15 gallon aqueon kit over the weekend for my daughter. It came with the power filter but the water is cloudy and fish are dying. I initially bought 10 guppies at first but some died after one day and bought another 5, again after a day only 3 are left? Is the filter not good enough? i had treated the with water conditioner when i set up the kit and also had the bag of fish floating in the aquarium for about 15 minutes before releasing them. My daughter also fed them twice a day per instruction. Filter only came with the cartridge with charcoal but no sponge.

    • Hi JR,
      You might want to read our articles of “Why did fish die” and “Aquarium nitrogen cycle and fishless cycling”.
      If you have any more questions, feel free ask us on the forum where it is easier to chat back and forth. 🙂

  24. Pingback: Top 3 Best Aquarium Filter Reviews In 2016 - The Rate Inc

  25. can you tell me the best place to buy Aquarium Filter:with cheap or discount price , but also with the same quality . do you think amazon is the best place or there others online shopping better .

    • You certainly can shop around, but it takes a lot of time. Usually Amazon has the best or near the best price for most items, and they have excellent customer service. I used to shop around a lot, but then found out I save quite some trouble by just shop with Amazon (most) of the time. To be honest, I got my first canister filter from Petsmart, but the price was not the best.

    • Yes, you can as long as you do not overstock your fish tank with too many fish. However, I’d recommend you to get a filter rated higher than the fish tank size to make sure you get enough filtration.

  26. Hi, I’m so glad to have found this site. I have a question and can’t seem to find any conclusive answers. I am buying a 400 Liter (105 Gallon) tank. With plants, fish, gravel etc, I guess it will be between 95 – 100 Gallons of water. NOW THE BIG QUESTION>>> I want to know whether I will be able to use two smaller internal filters that pump at the amount of liters per minute to add up to the total amount needed in stead of a large filter? For a 400 liter tank I need filtration of 1200 liters per hour…can I use 2 x 750 liter per hour Dophin F2000 filters instead of a large external power filter? Should I then use a sponge filter as well? Could I perhaps only use one Dophin F2000 and two sponge filters? What do you recommend? The external power filter will cost me R1650.00 where I will only pay at around R800.00 for both the 750 liter per hour ones which is less than half the price and still a bit pricey for my pocket but I will be able to manage the cost. I don’t want to buy this large tank if I can’t filter it well enough. Thank you so much.

    • Yes, you can use two smaller filters instead of just one big filter. However, it is hard to get “too much filtration”. So why not get two large filters instead of two small filters? 🙂 The only time the filter is too much would be it creates too much water current for the fish to handle. If you have any more questions, feel free to ask them on our forum.

  27. Have you missed out Top Filters by any chance? Or do they fall under one of those categories? Possibly under Power Filters?

    • I have not mentioned all of the top filters in this article. Most major brands make quality filters, and then it is just the matter of personal preference. Most people will recommend the filters they have been using for years (without a problem).

  28. Hi, think I am in the right website to get my doubt cleared… I am planning to upgrade my tank to 50 gallon.. Now my query is what type of filter should I opt for…is sponge filter enough or should i go for canister filter.. I know canister is always the best choise.. But it’s bit high for my budget as of now.. So I wana know whether sponge filter is do the work.. If so should I go with one big sponge filter or two smaller ones will be enough..

    • Sponge filter is fine, as long as you get big enough one(s). In my personal opinion, two smaller ones are better than a single big one if the total rated GPH is the same. In the case of two smaller sponge filters, you can do maintenance on one at a time with smaller chance to mess up the bacteria colonies in there.

    • If the budget allows, I would recommend canister filters. Your tank is on the large size, which requires a lot of filtration. Canister filters have the best filtration in real term, even when the Gallon Per Hour rating on the other filters are higher. Considering your aquarium size, I’d recommend two (instead of just one) canister filters. For example, you could do two x EHEIM Classic 2213 which give you total 120g manufacturer rated filtration. If your aquarium will be heavily stocked, get something higher rated such as 2215 or 2217. If the budget is a problem, you can also get two large Power Filters. Additional filtration can be obtained by install sponge filters on the intake of the canister and power filters.

  29. I just upgraded from a 20 Gallon tank to a 55 gallon long tank. I have a 350 L/h hanging filter in the tank. I love the sound of the waterfall noise the filter makes. But I have goldfish and know they need the better filtration. Would it hurt to add an additional sponge filter into the tank? The fish did great in the smaller tank the year they were in it, and I’m worried my current filter wont be enough. My tank has been modified to also be a coffee table (low on space) so I’m not too enthusiastic about a external canister filter.

    • Add additional filter is always welcomed, especially in the case of goldfish which have heavy bioload. The more filtration, the better. You can easily install sponge filter on the intake of your existing filter system to increase the filtration.

  30. Hi
    I have an 80 Gal aquarium and am looking for a filter. I do currently use an internal filter which sticks to the glass and has 2 filter sponges in it. Just dont know the wattage or capacity since it is 2 years old. What should be the wattage and liter/hr rate for the filter? I read in one of your posts to not to get a very high rated filter as it would bother the slow moving fishes. I was going to get a Chinese model (since that is all I can get) 40Watts 2800L/Hr. Do you think thats going overboard or is it ok? Since it is a chinese model, I suspect the specs wont be very accurate. Any help appreciated.

    • 2800L/hr is about 700 gallon per hour. For a 80 gallon tank, it is about to go through all of the water 9 times per hour which is more than efficient enough. What exactly filter are you getting? It would be fine if you can place the outflow in such way that the water flow does not directly bother the fish.

    • A canister filter would be the best choice for a large aquarium of your size. Pick one from EHEIM. They make high quality filters with low power consumption and low noise.

  31. Hi new here i have a 55 gallon aquarium I’ve been running it with 2 tank heaters to keep my temperature right for the fish downside is when i got it it had a Penguin 170 which i ran with a Tetra Wisper 10on other side of tank but just recently purchased a Tetra Wisper 30-60 to replace the Penguin 170 not sure what speed i should run them both on though for moving the 50+ gallons i know the higher the rate better for tank but most my fish are not large i dont want swimming in current to be to stressful

  32. Hi,
    I have a 60 liter tank and purchased a dolphin f2000 internal filter as my previous filter the cascade 80 filter broke.
    I installed the f2000 last night and it sounded like Niagara falls in my lounge, and my poor fish seem to be struggling to swim. it says 780/750 L/H on the box which seems a bit much for my tank. I did adjust the level on the filter to its lowest and I wrapped some bandage around the front where the water comes to hopefully lessen the current its making and slow down the speed of the flow. Now on top of the nozzle that releases the water there is a pipe that is 10/15cm long and on the end of that pipe is a black nozzle, before I blocked off the flow a bit there was no water coming from that pipe and now there is…. is that fine???? or will I blow the motor? …. should I get the smaller filter maybe the dolphin f1200 internal filter? , im scared for my fish — I have 1 black knife ghost fish, 2x panguese shark, and a algae eater fish —– someone please help

  33. i have a 92 gallons (us) wish tank. could you please recommend me the best filter i can have to keep the water clean for durable time.

    • Hi, jatin,
      For a 92-gallon fish tank, I recommend a canister filter. Just go with EHEIM mentioned in the article if you want high quality, low noise. An EHEIM Classic 2217 should be fine for the size. Or if you can go for the more modern versions if you have the budget.

      Filters do not keep aquariums “clean”. That is the job of gravel vacuum. 🙂 Filters keep ammonia at 0ppm which is essential for the survival of the fish.

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