The Ultimate Protein Skimmer Buyer’s Guide for Every Aquarium – Sumps, Nano, Freshwater Conversions, & AIO
Welcome to Simple Reefs. Today, we are bringing you The Ultimate Protein Skimmer Buyer’s Guide for Every Aquarium. We are going to cover the best options for every type of tank: aquariums with sumps, nano aquariums, All in One setups, and freshwater conversions with no sump at all. If you are going into this subject completely blind, you might want to read our ultimate beginner’s guide to protein skimmers first.
Table of Contents
The Ultimate Protein Skimmer Buyer’s Guide: In this complete guide, we are going to break down exactly which protein skimmer is right for your specific setup. We will look at the golden rules of sizing and bioload, explore the differences between AC and DC pumps, and finally give you our top picks for every budget and tank style.
Key Takeaways
- Aquariums with Sumps: The best case scenario. You have an abundance of space and options ranging from budget friendly to high end smart skimmers.
- Nano Aquariums with Sumps: Require compact footprint skimmers but still offer great flexibility. Be careful not to strip your low water volume of nutrients.
- All in One (AIO) Aquariums: Space is heavily restricted to the rear chambers. You will need a specifically designed narrow skimmer or a Hang on Back (HOB) alternative.
- No Sump / Freshwater Conversions: A Hang on Back (HOB) skimmer is your best friend here. If you lack rear clearance, an internal in-display skimmer is your only, albeit slightly uglier, choice.
The Golden Rules of Choosing a Protein Skimmer
Before we dive into the specific skimmers that will work for your tank, we need to cover a few golden rules that apply to every marine aquarium. Whether you have a massive 800 litre display or a tiny 52 litre AIO, the rules of choosing the right skimmer remain exactly the same.
💡 Quick Glossary: Aquarium Types Explained
If you are new to the marine hobby, you might be wondering exactly what we mean when we categorise these different setups. Here is a quick breakdown:
- Aquarium with a Sump: A main display tank that features external plumbing leading down into a separate, secondary tank (the sump) hidden inside the cabinet beneath it. This sump is where water is filtered and where all of your ugly equipment is kept completely out of sight.
- Nano Aquarium: A small marine setup that typically holds less than 75 litres (around 20 US gallons) of water. Because of their low water volume, they require very careful parameter management but are incredibly popular for beginners on a budget.
- All in One (AIO) Aquarium: A tank that has its entire filtration system built directly into a hidden compartment at the back or side of the display glass. There is no external plumbing or separate sump required.
- No Sump Aquarium: A standard glass box, much like a traditional freshwater tank, with no hidden compartments or external plumbing. All equipment must either sit inside the display or hang on the outside glass.
Size Matters, But Bigger Isn’t Always Better
All protein skimmers are rated by the amount of water capacity they are capable of processing. There’s a little caveat to that, however…
When a protein skimmer is rated for 125 litres, that rating assumes normal operating conditions. In other words, a typical bioload and a reasonable amount of organic waste in the water.
What we mean there is that it will handle 125 litres of water when all conditions are ideal – a normal number of fish relative to your tank’s size with a standard amount of waste.
Let’s be honest, we aren’t all perfect and sometimes we can’t keep the water as clean as we want to. That’s why it is a good idea to buy a protein skimmer that is slightly larger than your tank’s total water volume.
When you see that protein skimmer water volume rating, it’s under ideal conditions. If your tank is dirtier, the amount of water the protein skimmer can process will go down. With this in mind, it’s a great idea to scale up your protein skimmer size.
The golden rule here, assuming you don’t have a lot of fish, is to buy a protein skimmer that is around 25% larger than your aquarium’s actual total water volume. That way, the protein skimmer will work more efficiently even when there is extra waste to process.
💡Note: Before you go ordering your new skimmer, keep reading because we are about to make this whole calculation thing a lot more simple while still sticking to that 25% rule.
⚠️ Warning: Factor in Your Bioload, Too – The 40% Rule
When we talk about bioload, we are referring to the number of fish in your aquarium. The more fish in the tank, the more food and waste that will be entering the water column.
Protein skimmers assume a normal bioload. When your bioload increases, this rating goes down. Sometimes quite dramatically.
For example, a Red Sea RSK300 protein skimmer is rated for aquariums up to 850 litres but only if you have a light bioload. That figure drops to 280 litres if you have a high bioload.
If you have a lot of fish, assume that your bioload will be high and purchase your protein skimmer with that in mind. In heavily stocked tanks, increase that 25% rule to around 40–50% larger to accommodate the extra waste produced by a higher bioload.
Water Volume
To figure out your aquarium’s total water volume, take your aquarium’s display water capacity and add it up with your sump’s or rear chambers’ water capacity. That is your total volume. Many manufacturers will state this on the box or on the aquarium’s product listing.
This obviously changes if you don’t have a sump or all-in-one chambers. It’s safe to assume that, if you are converting a freshhwater tank, your water volume is literally just that of the tank itself. We don’t tend to include the extra capacity that comes with hang-on-back or external filters.
💡 Tip: Calculating Your True Water Volume
Working out your aquarium’s total volume is not as tricky as it may seem. Let’s take the hugely popular Red Sea Max Nano as an example. The manufacturer states it is a 75 litre system. This total capacity is actually made up of two parts: a 62 litre front display tank and a 13 litre hidden rear filtration chamber.
When choosing a protein skimmer, you should always base your choice on the combined total capacity of the entire system. In this case, that is 75 litres. Just keep in mind that adding heavy reef rock and sand will naturally displace a significant amount of water.
While it is technically a 75 litre system on paper, your actual true volume of saltwater might only be around 60 litres once it is fully aquascaped. Regardless, always use the manufacturer’s stated total system volume as your safe baseline for sizing any filtration equipment.
Do Rocks and Sand Affect Skimmer Sizing?
Yes, rocks and sand do affect protein skimmer sizing but that can actually make choosing a skimmer easier rather than harder.
Tank manufacturers state a total water volume based on nothing at all being in the tank other than water. Rock and sand displace water which means that you aren’t actually adding as much water to the tank as you may think.
In most reef tanks, rock and substrate displace around 15–25% of the total volume. That means a tank advertised as holding 75 litres may only contain 55–65 litres of actual water once it is aquascaped.
Conveniently, this actually works in your favour when choosing a protein skimmer because, in a lot of situations, it does the scaling up for us.
Because we talked about buying a protein skimmer that is about 25% larger than your system’s water volume, simply buying a skimmer rated for your tank’s advertised size usually lands you right in the ideal range once you have added rocks and sand.
For example:
- Tank size: 75 litres
- Actual water volume after rock and sand: ~60 litres
- Skimmer rated for: 75 litres
In practice, that skimmer actually ends up being roughly 20–25% oversized, which is exactly what most reef systems benefit from. In many cases, the simplest approach is also the correct one:
choose a protein skimmer rated for roughly the same size as your tank’s advertised system volume unless you have a heavily stocked tank.
Quick rule:
If your tank is stocked normally, buying a skimmer rated for your tank’s advertised volume will usually result in the ideal 20–25% oversizing once rocks and sand are added.
Can a Protein Skimmer Be Too Big?
Yes, a protein skimmer can absolutely be too large for your aquarium. Unfortunately, I have some experience with this.
The temptation to buy the biggest skimmer possible is pretty tough to overcome. Especially if you see a good deal. The truth is however, massively oversized skimmers can actually perform worse than properly sized ones.
Protein skimmers work by creating a stable column of foam that lifts dissolved organic waste out of the water. For that foam to form consistently, there needs to be a steady concentration of dissolved organic compounds in the water. We talk all about the process in our beginner’s guide to protein skimmers.
If a skimmer is far too powerful for the amount of waste present, it may actually struggle to maintain a stable foam head. Instead of producing dark skimmate, the skimmer may:
- produce very little foam
- constantly collapse its foam head
- require constant adjustment to stay stable
In other words, the skimmer simply doesn’t have enough waste to work with. The protein skimmer I purchased for my larger aquarium had this very problem. I snapped up a good deal and regretted it after consistently struggling to keep it dialled in.
📝 Note: What Does “Dialling In” Mean?
If you spend any time researching marine aquariums, you will constantly hear the phrase “dialling in your skimmer”. This simply refers to the delicate process of adjusting the balance of air and water inside the reaction chamber.
Your goal is to raise or lower the internal water level until the foam head breaks perfectly into the collection cup. It requires making incredibly tiny adjustments to the skimmer’s valves and then waiting 24 hours to see how the foam settles. Once you find that perfect sweet spot where the skimmer consistently pulls out dark, foul smelling waste without bubbling over, your skimmer is officially dialled in.
Oversized Skimmers Can Strip Nutrients Too Quickly
Even if an oversized skimmer is working correctly, it can sometimes remove nutrients faster than your aquarium ecosystem can replace them.
In extreme cases this can lead to issues such as:
- pale or starving corals
- unstable nutrient levels
- nuisance problems like dinoflagellates
That last one is particularly key. Dinoflagellates are a snot like growth that can starve coral and can be an absolute nightmare to remove. They are often caused my low or undetectable nutrients in your marine aquarium. Take a look at this thread on Reef2Reef for examples.
It sounds really counterintuitive, especially when you see so many people chasing extremely low nutrients, but most modern reef systems benefit from balanced nutrients rather than ultra-sterile water. A small amount of nitrates and phosphates can benefit your tank.
Your filtration should match the tank’s needs rather than overwhelm it. As we mentioned earlier, stay within the safe zone when it comes to oversizing your protein skimmer.
- 25% larger than the tank’s water volume for normally stocked systems
- 40–50% larger for heavily stocked aquariums
Within this range, the skimmer has enough extra capacity to handle spikes in waste without becoming difficult to tune.
Once you go significantly beyond that range, the skimmer may become inefficient or unpredictable.
AC vs DC Pumps
When we refer to AC and DC, we simply mean the type of water pump that the protein skimmer uses. AC pumps are a very basic water pump and have been around for years. Typically, if your protein skimmer is on the cheaper side, it will feature an AC pump.
They are less efficient and typically aren’t adjustable, but they are incredibly reliable and tend to last much longer. They are designed to be ran into the ground and tend to handle anything you can throw at them. Expect to pay a little more in electric to run them, though.
DC pumps, on the other hand, will often feature a controller to allow you to adjust the speed of the pump. They are more energy efficient and allow you to tune your protein skimmer far more easily, but they tend to be more expensive and can be slightly more prone to breakages.
| Aquarium Type | Placement Options | Special Considerations |
|---|---|---|
| Aquarium with Sump | In Sump | You have the most freedom here. Your main checks will be the physical footprint available in your skimmer chamber and the required running water depth. |
| Nano Aquarium (with Sump) | In Sump | Requires a compact footprint. You must be incredibly careful not to buy a massively oversized skimmer that will strip the small water volume of all nutrients. |
| All in One (AIO) Aquarium | Rear Chamber / HOB | Space is extremely tight. You need a narrow skimmer with a mounting clip, and the collection cup must be short enough to clear the rim of the tank. |
| No Sump / Conversions | Hang on Back (HOB) / Internal | You will need sufficient clearance behind the tank for a HOB skimmer. If you use an internal skimmer, it will take up valuable display space and can be an eyesore. |
1. Protein Skimmers for Aquariums with Sumps
If your marine aquarium is fairly large and connected to a sump, you are effectively in the best case scenario and have an absolute abundance of options. Having a sump opens up the majority of the protein skimmer world to you.
Your sump will almost certainly have a centre chamber where you can place your equipment, or perhaps even a dedicated chamber purely for the protein skimmer alone. Being able to add a stand to raise your skimmer to the optimal height in the water means a ton of options are open to you.
The only thing you need to give serious consideration to is the physical space available in the sump chamber.
High End Sump Skimmers
The world is your oyster if you have a decent amount of money to spend. High end protein skimmers offer a few perks that you just won’t find in the budget lines. Most tend to be more efficient, wireless control is a common option, some are maintenance free, and most are extremely silent.
- Red Sea DC Series: Red Sea offer an extensive range (DC300, 600, and 900) that cost a lot of money but are very efficient and require limited maintenance.
- Maxspect Aeraqua Duo AD600: Has a dual intake and dual needle wheel to skim like crazy. It features wireless operation and an external controller. Watching this thing in action feels like an evolution of the technology and I’m always a bit sad I would never be able to fork out for one.
- Deltec: Deltec have a very well regarded line of premium protein skimmers that process a huge amount of waste.
- Ultra Reef Akula UKS: They are knocking it out of the park with this beautifully machined series. Expect to pay upwards of £400 but you’ll get a protein skimmer that is head and shoulders above much of the competition.
Budget and Mid Range Sump Skimmers
Don’t worry, there are plenty of options to accommodate all needs and plenty of budget protein skimmer options if you cannot afford to spend a great deal of money.
Certain brands specialise in very economical solutions without compromising on quality.
- Bubble Magus Curve Series: Bubble Magus offer big savings for large aquariums with their Curve and Curve Extreme ranges. They are very well liked by the community and I use them myself.
- Reef Octopus Classic: Another brand that can be quite affordable. Their Classic range is very nice and offers options for all sizes of aquariums.
- TMC Reef Skim Pro: If you would like to stick with a British made option, Tropical Marine Centre offers this very affordable unit.
- Tunze Comline DOC 9012: A nice midrange option that comes with an external controller and DC pump.
2. Protein Skimmers for Nano Aquariums with Sumps
When we talk about nano aquariums, we are typically referring to aquariums that max out at about the 75 litre range for the display with a little extra capacity for the sump.
The big problem with nano aquariums is that the lower water capacity means waste can accumulate faster, is less diluted, and can cause massive problems in the blink of an eye. This is why a protein skimmer can be a massive upgrade to your nano tank.
There is a huge range of nano specific protein skimmers you can purchase for your sump. Again, the main consideration is space and the capacity of the skimmer. You want to make sure your skimmer isn’t too large for the total water volume of your tank or too large to fit into your sump.
The protein skimmers listed here are all small form and should be perfect for a nano aquarium with a sump.
Budget Nano Sump Skimmers
All of these options cost less than £30 which is pretty damn cheap for a protein skimmer. As you may expect, results are very variable with this collection.
- A Basic cedar wood air stone option (Starts from about a tenner on Amazon)
- Aqua Excel AE-NANO40 – AliExpress
- Resun SK-300 – AliExpress
- Boyu WG 308 – AliExpress
I know, that AliExpress tag is a bit scary but I have purchased protein skimmers from there before that have worked great.
Mid Range Nano Sump Skimmers
This is where you are likely to find your best balance of quality to price. These mid-range nano protein skimmers cost between £30 and £100 but are all very well reviewed. You may even be able to save some money by purchasing secondhand.
- Bubble Magus Mini Q & BM-QQ2: Bubble Magus are topping the lineup here. I am currently using their Mini Q protein skimmer in my Red Sea Max Nano and it is so damn quiet. I love it!
- Bubble Magus Nano 40 & 70: Designed to sit in the water in your sump like a standard skimmer and features typical Bubble Magus build quality and efficiency.
- Red Sea Desktop Skimmer: Looks small but can be trusted thanks to Red Sea’s quality.
- Fluval PS1: I would advise caution here. Some people absolutely hate them and claim they can’t be tuned and are very noisy.
High End Nano Sump Skimmers
All of these start from at least £100 and go up to over £200. Many offer additional features like pump control, space saving designs, and silent operation.
- Tunze 9001 and 9004: Available in both AC and DC formats. Very well regarded by the marine aquarist community. I’ve used the Tunze 9001 and found it to be pretty good.
- Bubble Magus Z5: A fantastic space saving option.
- Reef Octopus Classic 150 Space Saver: Designed for larger nanos with good sized sumps and bigger bioloads.
- Sicce Shark: I am a big fan of Sicce. Their warranty goes above and beyond and their customer service is fantastic. This is a chunky protein skimmer, too.
- TMC Reef Skim: A reliable British option for smaller setups.
3. Protein Skimmers for Nano and All in One (AIO) Aquariums
What about the middle child of the marine aquarium line up: the All in One aquarium? This includes popular setups like the Red Sea Max Nano, Waterbox 20, Fluval SEA Evo 52L, and the Fluval Flex.
Naturally, this section includes nano aquariums without sumps as the vast majority tend to also be All-In-One style. If your nano aquarium isn’t an all in one, take a look at the hang on back protein skimmer options coming up.
All in One aquariums have a hidden section at the back or side which contains chambers for filtration. The difficulty here is that controlling the height of your protein skimmer in the water can be quite tough, as can finding a protein skimmer that fits neatly into the chamber section which typically has very limited space.
💡 The AIO Skimmer Checklist
If you are buying a skimmer for the rear chambers of an AIO tank, it must meet three strict rules:
- It needs to be narrow, fairly short, and not too wide so it doesn’t interfere with chamber walls.
- It needs a mechanism to attach it to the side or back of the aquarium (like a clip or magnet).
- It needs to have a narrow and short collection cup so it doesn’t protrude awkwardly over the top of the display.
Compact Internal AIO Skimmers
These options assume that you want to house the protein skimmer directly in the filtration section of your all in one aquarium.
- Bubble Magus Mini Q: Very efficient, very quiet, and comes with a clip to hang it onto the back of your aquarium allowing a lot of depth adjustment. It ticks all the boxes.
- Bubble Magus BM-QQ2 & Z5: The Z5 is incredibly narrow. You may need to fashion a shelf using some egg crate to act as a stand in the chamber.
- Tunze Comline DOC 9001 or 9004: A bit on the large side but they come with a magnet. The 9001 is smaller and easier to accommodate.
- Wavereef Protein Skimmer Nano Box: Designed specifically for All in One aquariums and features a clip.
- Hydor Slim Skim: Quite narrow with a very short cup but is extremely long.
Hang on Back (HOB) Skimmers for Nano Tanks & AIOs
If you need more skimming power and have space behind your aquarium, you can opt for a hang on back protein skimmer. You will need to make sure they will fit horizontally as a lot of HOB skimmers are quite wide and need space for an intake and outtake pipe.
- Bubble Magus BM-QQ1 & BM-QQ3: The QQ1 is particularly great and very silent. The QQ3 is basically a bigger version capable of processing more water.
- Reef Octopus Classic 1000 HOB: If you are really pressed for space, this might be a better choice. It is quite economical when it comes to size but fairly expensive.
- Reef Octopus Classic NS80-Nano: A great choice for smaller tanks with less space.
- Aqua One NanoSkim 90: Seems to share a similar design to the Bubble Magus BM-QQ1.
4. Protein Skimmers for Aquariums with No Sump
If you have a large freshwater aquarium that you are converting to a marine aquarium, your protein skimmer options are limited but it is totally doable.
Don’t be put off by people telling you that you absolutely need to have a sump to run a healthy marine tank. Countless hobbyist’s experience proves that wrong.
There are, however, a couple of things that you will have to accept. The most noteworthy is that your aquarium will never have that clean, uninhibited by equipment, look. You will have to make some compromises.
We really need some space behind or to the side of the tank to accommodate the protein skimmer, as well.
The Best Choice: Hang On Back (HOB) Skimmers
If you have space behind your aquarium, Hang on Back protein skimmers are your best friend. They work by feeding water into the reaction chamber from your aquarium and then returning it back once it has been processed. The skimmer sits out of the water and only minimal parts of the equipment are visible in your display.
For Nano Conversions (Under 120 Litres):
- Bubble Magus BM-QQ1: Very discreet, barely noticeable in the water, sits low on the back of the tank and is very quiet. The tinted cup hides the ugly waste.
- Reef Octopus Classic 100-HOB: Looks fantastic, discreet, and can process a ton of water (50-400 litres). Quite expensive, though.
- AquaReady Bullet 1 & 2 HOB: Premium options for smaller capacities.
For Larger Conversions:
- Bubble Magus E3, Q3, and Q5: I have used the E3 extensively and it is a fantastic protein skimmer that is very capable on moderate sized aquariums.
- Deltec MCE400 & MCE600: Very premium options. Expect high quality and for them to be able to process a massive amount of waste.
- IceCap K3 100 HOB: Comes with a DC pump and controller so should be easy to tune and very efficient.
- Reef Octopus Classic 1000 & 2000 HOB: Very slender options if you have limited space behind your aquarium.
What if I Have No Space Behind My Aquarium?
If your tank is flush to the wall, your only option is to place an internal protein skimmer directly in your aquarium display.
I would highly suggest you try to avoid this because you may end up hating it, but it will work. It will look a bit ugly and it will probably grow algae on the outside and inside.
If you must go this route, look for dark coloured, low profile skimmers that will blend into a black background.
The Tunze 9001 and 9004 are sleek, black boxes that don’t look entirely out of place. The Sicce Shark 150 is another excellent choice with a class leading 5 year warranty. For nano tanks, the Bubble Magus Mini Q or BM-QQ2 are tiny enough to hide behind rockwork.
In Short
There are protein skimmer options for the vast majority of scenarios. Be it high bioload, minimal bioload, huge sumps, restrictive All in One chambers, or freshwater conversions with zero rear clearance. Just be careful to pick a skimmer that is correctly sized for your total water capacity and capable of handling the bioload of your specific tank. Thanks for reading and spending your time at Simple Reefs.
Frequently Asked Questions
Do I need to buy a bigger protein skimmer than my tank’s capacity?
It is generally good practice to buy a skimmer rated for 25% to 50% more than your total water volume, especially if you have a heavy bioload (lots of fish). However, do not buy a massively oversized skimmer as it will be incredibly difficult to tune and may strip your water of all nutrients.
What is the difference between an AC and DC skimmer pump?
AC pumps are traditional, highly reliable workhorses that run at a single speed. DC pumps are more modern, energy efficient, and come with a controller that allows you to finely adjust the speed of the motor, making it much easier to dial in your foam production.
Can I put a protein skimmer in a tank without a sump?
Yes. You can use a Hang on Back (HOB) skimmer that sits on the outside glass of your display, or you can place a compact internal skimmer directly inside the display tank. HOB skimmers are vastly preferred as they do not clutter the display area.
Are cheap protein skimmers worth it?
Many budget brands like Bubble Magus and Reef Octopus produce fantastic, highly reliable skimmers. Even traditional limewood air stone skimmers that cost less than £10 will successfully remove dissolved organics, though they require more frequent maintenance and are harder to tune.
