Best In-Sump Protein Skimmers For Reef Tanks – Reviews & Guides

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The best protein skimmer is a thing you can’t skimp on when it comes to cost with a saltwater fish tank. If you have spent any time at all keeping marine fish or corals, you understand how hard it is to keep water conditions clean enough for them to not only survive but also thrive. Those who choose to fight this battle without the use of a protein skimmer usually find themselves on the losing end, which unfortunately often results in dead livestock. There are a lot of ingredients to having a marine aquarium, and the one at the top of the list should be the use of a quality protein skimmer.

What Is A Protein Skimmer?


A protein skimmer is one of the most important devices in a saltwater aquarium and is the most efficient way of removing organic compounds (including proteins and amino acids) from the marine aquarium water. This prevents them from breaking down into nitrogenous waste, which is dangerous for fish and other organisms living in the saltwater aquarium.

This device is made to utilize a process called foam fractionation in order to physically remove dissolved organic compounds (especially protein) not allowing them to decompose. Foam fractionation is the process of using foams, or air bubbles to transport organic compounds out of aquarium water. Thanks to that it lightens the load on the biological filter (live rock, live sand) and it improves the water redox potential.

How Does A Protein Skimmer Work?

As stated earlier, all protein skimmers use the process of foam fractionation. In basic terms, foam fractionation is the process of using foam, or air bubbles, to transport waste particles out of aquarium water.


When the protein skimmer is functioning, the water pump pumps aquarium water and air from the air intake into the main tube of the skimmer (skimmer body). The pump consists of a motor-impeller that helps to mix the air and the water resulting in millions of tiny bubbles that fill the skimmer body. Since those bubbles are filled with air, they float to the top of the tube. As these bubbles rise, tiny particles of organic waste from the water attach themselves to the bubbles and ride to the top of the tube and overflow into the collection cup for removal.


Most protein skimmers are equipped with a flow control on the top of the water output (the previous picture). The flow control works by expanding or narrowing the water outlet, thus allowing you to achieve proper water levels you want in the skimmer body.

As you can see, the fundamental of protein skimmers is fairly simple – uses air bubbles in the water to remove organic waste. The most effective skimmers are those able to produce the tiniest and largest amount of bubbles because the total surface area of the bubbles dictates how much waste can be removed in any given time period. The newest models of protein skimmers replace the standard impeller of the pump with the new need-wheel impeller for producing much more bubbles.


Types Of Protein Skimmers

Protein skimmers come in in-sumphang-on-back, and internal models.

Great Skimmer At A Very Fair Price - Editor's Choice
  • Perfect & Quiet
  • Easy to use and set-up
Excellent Skimmer - high quality
  • Easy to install and operate
  • Easy to adjust and clean
Best Protein Skimmer - Best Value
  • keeps tank clean
  • easy to install and use
  • working perfectly

Most protein skimmers are made to operate in a sump, which is a smaller tank usually kept under the main tank inside the stand, where it is hidden from view. The sump tank provides a great place outside the main aquarium for you to set up a powerful filtration system. You can set up a wet/dry filtration system and place as much live rock as you can in the sump for the superior biological filtration. Sumps are very important for the success of medium-large reef systems that stock many fish and corals.

If you don’t want to have a sump setup, there are also Hang-On-Back and internal types of protein skimmers for you to choose. The hang on back type of skimmers are those that are made for smaller tanks, but it is possible to find this type for a medium-sized system. The internal type of skimmer is usually very small and compact in size that allows it to be placed well inside aquariums. This type is usually designed to be used in nano reef tanks that are smaller than 20 gallons.

How To Choose The Best Protein Skimmer?

How to know if a protein skimmer is best?


A good skimmer performing at a high level can be the difference between an amazing system and one that has unhealthy and even dying livestock. It is not cheap, but having one that operates properly is vital for the health of your aquarium system. Those who have a reef tank already understand how important water quality is in keeping your livestock healthy and thriving in your tank.

As mentioned in the previous section, the fundamental of protein skimmers is to use air bubbles in the water to remove organic waste. So, the most effective skimmers are those able to produce the tiniest and largest amount of bubbles because the total surface area of the bubbles dictates how much organic waste can be removed.

Based on the total volume of your reef system

One of the most important things to remember when considering a protein skimmer is to make sure you choose a unit that can handle the volume of your tank. If you take a shortcut and choose a model rated for a 75 gallon tank when yours is actually a 90 gallon tank, you are fighting a losing battle. If anything, you should choose a protein skimmer that is rated for a tank capacity higher than that of your tank. It is well worth the extra money to go a little larger, especially when you consider the cost relative to the cost of the rest of your equipment and livestock.

One common mistake people make is to not count their sump capacity when determining which size protein skimmer to purchase. If you have a 75 gallon tank and a 20 gallon sump, you really have a 95 gallon system, so your skimmer should be rated for at least that number of gallons. As you read through our protein skimmer reviews you will see that most brands offer skimmers in several different sizes with both the pump and the overall unit varying in size and power.

The space you place your sump is small or large


Another common mistake is to know what size skimmer you can fit. If you have a sump in the cabinet under your tank, you are limited in the space available, particularly the height available under the cabinet. The first time I had a reef tank with an in-cabinet sump, I did not pay any attention at all to the height needed when I ordered my protein skimmer. As I put the unit together it suddenly hit me that I might have a real problem fitting the skimmer under my cabinet. I got lucky and it fit, but the lesson was learned and I have since read some stories of others who made the same mistake and were not so lucky. For that reason, I want to stress how important it is that you check the dimensions of the skimmer you want against the amount of space you actually have.

Best In-Sump Protein Skimmer Reviews

Bubble Magus BM-Curve 5 For Tanks Up To 140 Gallons - Great Skimmer At A Very Fair Price

The Bubble Magus BM-Curve 5 can work with aquariums that hold up to 140 gallons of water. It uses an SP1000 pump (22W – 120 V/60 Hz) with a venturi intake to produce a huge amount of air bubbles in its reaction chamber. It is fitted with a bubble plate that helps to reduce the turbulence in the reaction chamber for expanding the contacting time between the tiny bubbles and the organic waste in aquarium water. This design makes it very effective in handling organic waste produced by your fish and corals.

It comes with most things of a high-quality protein skimmer and is very easy to install and use. Even a first-time owner will have no problem getting them up and working. It is almost noiseless, does the job it is meant to do, is easy to maintain and clean, and is definitely good value for the money. It is also very energy efficient with the pump wattage of only 22W making it the best choice when it comes to reducing operating cost.

The SCA-302 is a good buy for anyone who owns a heavy load saltwater reef tank and is looking for an efficient skimming machine. The materials used in the construction of this skimmer are not only aesthetic but also durable and long-lasting. It comes with most essential features of a good protein skimmer such as a powerful pump (700 GPH, 41 watts – 110 – 120 V/60 Hz) with needle wheel impeller, air silencer, flow control…

The SCA-302 is relatively easy to install. The water levels recommended for the skimmer to work best are in the range from 6 to 7 inches. Its dimensions are 9.5 inches long, 9 inches wide and 18 inches high. The compact design and small footprint make it easy to place in a sump tank.

Pro Tip

The SCA-302 is powerful, efficient and costs a very affordable price compared to other protein skimmers that are rated for the same tank size. It is surely a great investment for saltwater aquariums smaller than 180 gallons.

This is one of the best skimmers that are rated for large reef tanks up to 210 gallons. Its water pump is fitted with a 6-inch needle-wheel impeller which helps to shred the incoming air into fine bubbles. As you know, the size and number of bubbles determine the effectiveness of foam fractionation as well as the entire skimming machine. It also comes with a gate valve that makes water level adjustments much easier for ensuring the effectiveness of skimming process.

This skimmer is well made of good quality materials for preventing it from being damaged easily and lasting for a longer lifetime. Its main chamber is specially curved to help remove dirty bubbles easily into its collection cup. The cleaning and maintenance are also very easy with its quick-release collection cup. To clean this model, you just need to snap the collection cup off and clean it with clean water. This model is a compact option and runs very quietly.

The Reef Octopus Classic 202-S is the best choice for 180 gallon heavy load, 200 gallon medium load, or 265 light load reef tanks. It uses a Reef Octopus Aquatrance 3000s pinwheel pump (211 GPH, 35W) to operate the entire system. The pump is so powerful, its flow rate is 211 gallons per hour and strong enough to keep a good circulation to constantly filter a heavy biological load reef system.

The product is made of heavy-duty materials to help prevent it from easily breaking. The skimmer body features a unique cone design that helps it to better remove matured bubbles, which contain a large amount of organic waste on their surfaces, out of your aquarium water. Its collection cup with a drain hose can be connected with an external collector for containing more skimming waste and reducing cleaning times.

Pro Tip

The Reef Octopus Classic 202-S is fairly easy to install. The water levels recommended for the skimmer to work best are in the range from 7 to 9 inches. Its total height is up to 23.2 inches and the footprint measures 12.4- by 10-inch. You should ensure that the space in your sump where you plan to place the skimmer is large and high enough to accommodate it.

There are many models available for saltwater and reef tanks from 100 to 1100 gallons. This model comes with new technology pumps with innovative ROTORMIX brush impellers for better foaming and high air concentration in the main chamber. Its clear construction will help you to see when this protein skimmer is working and make sure everything is running smoothly.

Its collection cup has a drain hose that can be connected to an external collector. This will help to prevent you from having to clean your collection cup often. It also comes with a venturi silencer – an air intake that is specially manufactured for reducing operating noise. Its water output hose is fitted with a flow control for you to adjust the water level inside the skimmer body to make it fit the water level in your sump tank.

Pro Tip

This product is energy-efficient and quiet so you won’t have to worry about it being loud while it’s running or using a lot of electricity.

Benefits Of Using A Protein Skimmer

  1. Reduce Phosphates

    The high levels of phosphates in your fish tank can lead to the overgrowth of harmful algae. This can end up irritating the aquarium water quality as well as your fish, corals and other livestock. A protein skimmer can help to remove redundant nutrients (protein, amino acid, and other organic compounds) in the water and intermediately reduce phosphates, which are decomposition products of the unwanted nutrients.
  2. Lower nitrates

    As you know, too many nitrates can lead to the water uncomfortable for some fish and corals. Protein skimmers help to lower nitrates in aquarium water by removing their ancestor nutrients, which degrade into nitrates by the activities of microorganisms.

  3. Increase the oxygen concentration

    Your fish need to have an adequate amount of oxygen in the fish tank and protein skimmers can help with that. By directly injecting air into the water and improving its quality, these skimming machines help increase oxygen concentration in the water so your fish can be happy.

  4. Maintain proper water pH levels

    The water in a fish tank needs to have a healthy and stable pH range so the fish can be comfortable. Protein skimmers help with maintaining the proper water pH because they work to remove harmful particles and redundant nutrients from the water. This in return can lead the water being a safe environment for the fish to swim in.

  5. Remove the layer of nutrients from the water surface

    Sometimes fish tanks will get a thin layer of nutrients floating on the top of the water. This can end up blocking the needed light that your corals need for photosynthesis. Protein skimmers will help to make sure that this doesn’t happen by removing the particles that cause those surfaces to occur.

  6. Reduce the number of times you need to clean the fish tank

    One very helpful benefit that protein skimmers have is that they will work to help reduce the number of times you need to clean your fish tank. This is because they work to remove most of the harmful particles and substances in the tank that you would otherwise need to spend time doing yourself.

How To Set Up And Tune An In-Sump Protein Skimmer?

The first step in setting up your in-sump protein skimmer is to thoroughly rinse all components in water to remove any manufacturing residues. Do not use any detergents or cleansers as they are often not removed thoroughly and they can negatively impact your aquarium water quality.


Place the protein skimmer into your sump at the correct water level. The optimal water level will be determined based on the skimmer model and manufacturer’s guidelines. In some instances, a stand can be used to elevate the skimmer, while in other cases baffles can be used to increase the water level.

An important thing to remember is that all skimmers need a break in period. This means your skimmer might be set at the perfect setting but not produce much in the way of waste for a few weeks. This is because the surfaces of the skimmer need time to become part of the system. Once your skimmer is broken in and the correct settings are in place, you will be able to develop a routine for cleaning your collection cup. The results left in that cup will be the proof that your skimmer is working as expected.


Fully open the skimmer outlet (return to the structure guide) to maximize water flow and maintain the foam level at the lowest possible level. Run the skimmer at this setting for two to four weeks to allow the protein skimmer to break in. A thin protein layer will form on the inside of the skimmer which will help the foam to rise up into the riser tube and the collection cup. During this time you may experience an increase in micro-bubbles released in the sump, and you may even have foam overflow. This is normal and can be mitigated by performing additional water changes and increasing the sump filtration.

After the break-in period, you will want to adjust the water flow rate and foam level. The foam level is adjusted by turning the output valve and should be adjusted in small increments with about 24 hours between them. A lower foam level produces a darker and drier skimmate while a higher foam level produces a lighter and wetter skimmate which will fill the collection cup more quickly. There is currently debate over whether a lighter or darker skimmate is better and indicative of skimmer efficiency, but it ultimately comes down to preference and manufacturer’s guidelines.

How To Maintain A Protein Skimmer?

Keeping your protein skimmer clean is important to maintain a properly functioning skimmer. Empty and clean the collection cup regularly, at least once or twice a week, ensuring that you remove the slime in the riser tube so that it does not fall back into the clean water. Remove any salt build up, small rocks, and snails from valves and intakes, and keep the air intake valves clean and free of debris. Clean the protein skimmer pump thoroughly about every three months to maintain optimal performance. Replace air stones regularly (if present).

A common problem that can occur is that the protein skimmer can overflow even after it is broken in. This generally indicates that there has been a change in water viscosity in your aquarium often related to the addition of water additives, conditioners, or medications. A large water change can help to alleviate the overflow. Alternatively, you can turn the protein skimmer off for a few hours to allow the foam level to dissipate.

Regular cleaning and maintenance of your protein skimmer should ensure a long life of effective filtration. Each model is different and you should follow the provided instructions for the specific set up, tuning, and maintenance.

Top Editor's Choice on Protein Skimmer

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