What Size Protein Skimmer Do I Need? (The Definitive Guide)

What Size Protein Skimmer Do I Need?

This is the ultimate guide to choosing the right size protein skimmer for your saltwater tank.

In this comprehensive guide I will cover:

  • How to choose a protein skimmer
  • Skimmer vs tank size
  • Types of skimmers
  • Skimmer maintenance
  • And much more

Choosing a protein skimmer for your tank is a big decision. There are many factors that come into play. Type, size, cost, brand, are all things you need to consider. One of the most common factors you will need to decide on is size. What size protein skimmer do you need for your tank?

I mention in the article best protein skimmers for saltwater tanks, that a protein skimmer is a type of mechanical filter that removes organic compounds from your aquarium water.

Things like waste, uneaten foods, toxins, and bacteria are all things that a protein skimmer helps remove.

Protein skimmers play an important role in your saltwater tank. They help remove organic waste before they have a chance to break down in your tank releasing nitrogen compounds.

They will also help reduce Nitrate levels which is crucial for reef tank keepers.

In this article, I will explain how to choose the right size protein skimmer for your saltwater tank.

How To Choose The Right Size Protein Skimmer

The manufacturer of the skimmer will give a maximum tank size rating for each protein skimmer. Most times this number will be based on a light, medium, large bioloads.

Tanks that are heavily stocked with fish and corals will require a larger protein skimmer.

For example, the AquaMaxx HOB 1.5 protein skimmer is rated for tanks of 60-90 gallons. 60 being for light bioload and 90 for heavy bioloads. So it’s important to note the manufacturer’s recommendation for the tank size rating.

Also, you have to take into consideration your tank’s total system volume vs the main display water volume. Do you have a sump?  If so, then you need to add that to the total.

For example, if your main display tank is 90 gallons and your sump holds 30 gallons, then you will need a protein skimmer that is rated for at least 120 gallons.

Some manufacturers say that their ratings are based on the main tanks display water volume since this is where most of the bioload is concentrated. They don’t take sump water volume into account.

For me personally, I always account for the total system water volume including the sump area. I will also use the heavy bioload number as a rule even though I might only have a light bioload in the tank.

It is ok to oversize your protein skimmer? To a point. I will explain that shortly.

Another recommendation is to use the skimmers rated air intake capacity when determining the proper size.

For example, the Bubble Magus Curve 5 skimmer has an air intake rating of 300L/H or 80GPH so if you had a heavy bioload you can use this on an 80-100 gallon tank. This skimmer has manufacturers rating up to 140 gallons for light bioloads.

Formula to help determine protein skimmer size: (This is just a rule of thumb)

My tank size is  = _______.
I have this much bio-load = _______.
I have this much space to allow for the skimmer = ___X ____ X _____.
My budget is = ______.

Let’s keep using the Bubble Magus Curve 5 as an example and look at all the info above to see if this skimmer will work for our tank.

  1. Manufacture tank size recommendation: Max 140 gallon with light bioload
  2. Air intake rating: 80 GPH
  3. Tank size is 90 gallons including sump tank
  4. Bioload: 1 Coral Beauty Angelfish, 5 Blue/Green Chromis, 1 Royal Gramma, a small clean up crew, and 2 Frogspawn corals. I would consider that a light bioload.
  5. Space to fit skimmer in sump is 20″ X 18″ X 24″
  6. Budget is $250

So would this skimmer size work for you? Yes! It would be a great choice.

If you can afford a higher rated skimmer and your space permits, then you should consider buying a skimmer that is rated slightly higher than your tank requires. You might increase your bioload as time goes on so it wouldn’t hurt to have a larger rated skimmer providing it is not way oversized for the tank.

Is A Bigger Skimmer Better?

Not necessarily. Some people will say that you should get a protein skimmer that is way oversized for your tank if you can. What is wrong with over skimming right?

Well, that’s not always a good thing. There is a reason why manufacturers rate the skimmers the way they do.

Yes, you can use a skimmer rated for 120 gallons on a 90-gallon tank. I recommend you do. But I wouldn’t suggest using a 240-gallon skimmer on a 90-gallon tank.

I actually would prefer to use an undersized tank versus an oversized one. Here is why.

It can be problematic to use a skimmer that is drastically oversized on a small tank. The skimmer will not work consistently and you will not get the performance out of the skimmer that you desire. Protein skimmers need to perform continuously to get proper results.

If you have a skimmer that is hugely oversized, the skimmer will work for a few days then shut down and not perform well for a few more days as the organics get removed.

As the organics build back up, the skimmer will kick in again. So this inconsistency of working hard to remove organics then shutting down is not allowing the skimmer to perform at its full capability and degrades the performance.

I have experienced this myself. I had a Bubble Magus QQ3 protein skimmer on the back of a 30-gallon tank. It is a great skimmer and although it worked fine on the tank, I noticed how inconsistent it was with removing organics and filling the skimmer cup. Some days it would be full and skimming wet while other days it was a darker dry skim.

I ended up selling that tank and I moved the QQ3 onto a 90-gallon tank. What a difference it made. The skimmer was performing much better and with a few adjustments on the height of the skimmer collection cup, it was working great.

protein skimmer vs refugium

Pro tip:

I was really interested in learning more about the overall efficiency of a protein skimmer and found this bit of info. If you want your skimmer to perform at it’s maximum, 5 things have to take place. (Info taken from Wikepedia.com)

For more information on using an oversized protein skimmer, check out this article from Reefbum.com.

So how do you know if you have the right protein skimmer size?

  • Take into consideration your total system water volume
  • Use the Heavy bioload rating if you want to be on the high side
  • Avoid using a skimmer that is way too big and oversized for your tank
  • Does your tank size meet the manufacturer’s rating?
  • Check to confirm the skimmers rated air intake capacity is suitable for your tank size
  • Do you have enough space in your sump tank? Will the skimmer fit?

Do you really need a protein skimmer?

No, you don’t need a protein skimmer on your tank. This is an often debated topic in the saltwater hobby but the emphasis should be put on the word need. Is it needed? No. Should you have one? Yes. Some people like to use a refugium as well. There are different types to choose from and they can be used in conjunction with a skimmer if you like. Read Protein skimmers vs refugiums. 

There are huge benefits to using a protein skimmer:

  •  Helps keep your water free of toxins
  •  Huge support to your filter system in keeping the tank clean
  • They also help increase oxygen levels and overall water quality
  • Helps maintain low nitrate levels
  • Increases oxygen in the water
  • Helps to keep water clear
  • Better light penetration
  • Improved coral growth
  • Improves overall health of your system

Types Of Protein Skimmers – What Are My Options?

There are plenty of options when it comes to choosing the right skimmer for your tank. No matter your tank size or budget, there are some great options. The most commonly used types of skimmers today are:

  • Hang On Back (HOB) Style
  • In Sump Style

Other types include:

  • In-Tank Style
  • External Style

The most commonly used skimmer types would be the hang on back and in sump styles. HOB or hang on back protein skimmers are designed to hang off the back of your tank using the tank’s trim.

The manufacturer of the skimmer will provide you with the proper pieces needed to fit it onto your tank.

These skimmers are very effective, easy to use and convenient. But a downfall of them is they require space behind your tank and can be an eyesore depending on the type you choose.

In sump protein skimmers are used inside a section of your sump tank. These are meant to sit inside the sump skimmer chamber at a certain water level depending on the skimmer you are using.

Sump chambers can be different sizes so it’s important to not only purchase a skimmer that is sized correctly for your tank but sized to fit your sump as well.

There are many benefits to having an in-sump protein skimmer versus a Hang on back style. One being that it will be hidden within your aquarium stand so you won’t see cords and equipment hanging off the back of your tank.

Some larger tanks will require a very large skimmer which hanging off the back of your tank is not possible or ideal.

Another advantage is in the event of a skimmer cup overflowing, it will simply flow back into your sump tank and not all over your floor which is possible with a HOB skimmer.

If you have the option of using a sump system on your aquarium, I recommend you use an in-sump skimmer.

Skimmer size vs Tank Size – My Recommendations

There are so many different sized tanks in the hobby, it’s impossible to cover them all. But here are some great examples of tank sizes and skimmers that are best suited for each one.

Best protein skimmer for a 55-gallon tank

A 55-gallon tank is a very commonly used size. The standard size is 48″ X 20″ x 13″ which is not a huge tank but small either. It’s a perfect sized medium tank for a reef tank. A great thing about this size tank is there are plenty of protein skimmer sizes that are suitable for it.

You can choose a hang on back skimmer if you don’t have a sump system. If you do have a sump, you might want to choose an in-sump skimmer.

Hang On Back (HOB)

The AquaMaxx 1.5 HOB would be my first choice. It is slightly rated higher than a 55-gallon tank but if you have a high bioload it will work. This skimmer is easy to set up and use. It only requires about 4″ of space behind your tank to fit.

Other features and specs:

  • Durable and long-lasting design
  • Efficient and Reliable
  • Dimensions : L 7.5 x W 3.5 x H 17 Inch
  • Fits up to a 3/4″ rimmed tank
  • Uses an AquaMaxx SHARK 1.0 pump
  • Power usage 11 watts
  • Enlarged bubble diffusor and reaction chamber
  • Quiet operation
  • Easy to clean and maintain

What Is The Best Protein Skimmer For Biocube 32 Gallon Tank?

I guessed asked this question a lot and since I have a Coralife Biocube 32, I figured I would answer it here. The Biocube 32 is a bit difficult when it comes to choosing a skimmer for it. There are options but they are limited.

There is only 1 protein skimmer that works with this tank if you plan to leave the hood on it. That is the Coralife protein skimmer. This skimmer doesn’t get a lot of great reviews but I have used it on my tank for a few months and had no issues with it. I wouldn’t say it’s a powerhouse but it was designed to fit into the first chamber of the sump section of the Biocube tanks with the hood closed.

If you are going to remove the hood of the Biocube 32, then you have more options when it comes to choosing a skimmer. The most popular choice is the Tunze 9001. This skimmer fits nicely into the rear sump chamber but only in the middle section.

It’s a drastic improvement over the Coralife skimmer and you will get much better performance. But of course, the downfall is you have to remove the hood or perform some sort of modifications in order for it to be suitable.

Another option is the Aquatic Life 115. This is a great protein skimmer that is small and will fit into the first chamber of the sump section. The advantage of that being it leaves the whole middle section open for media or a refugium.

It will perform better than the Coralife as well but not as well as the Tunze 9001. So it really depends on what you are looking for. For me personally, I have the hood removed on my Biocube 32 and went with the Aquatic Life 115. I wanted the middle section open for upgrades and refugium. There are so many upgrades you can perform on the Biocube 32 which I listed here if you are interested in beefing up your tank.

I have put together a selection of protein skimmers that I recommend for various tank sizes. keep in mind this is for a heavy bioload demand. If you have a lighter bioload, you can go with a smaller skimmer but I recommend you stick with the heavy.

How Deep Should My Protein Skimmer Be?

Every skimmer could be different with respect to the recommended water level in your sump. In order for the skimmer to operate efficiently, it will need to be at a certain water depth.

The manufacturer will show you what the water depth should be for each specific model.

For example, the Simplicity 120 DC protein skimmer manufacturer recommends a water level of 7-9″ in the sump for optimal performance. You may find that after using the skimmer for a while, it’s most effective at a certain level and will “settle in” at maybe 7.5″.

Protein Skimmer Maintenance And Cleaning

When choosing the right size skimmer for your tank, you should also consider the amount of maintenance and cleaning it will need. If you have a very large tank of say 300 gallons, you will need a very powerful and large skimmer to handle that size tank.

Regular cleaning and maintenance will be needed regardless of skimmer size so it’s something that you will be removing from your sump tank periodically. The collection cup will require emptying and cleaning more often.

So depending on how much space you have in your sump and underneath the cabinet will play a role in the size protein skimmer you buy. Also, keep in mind that these large skimmers are quite bulky and heavy which may not be an option for you when it comes to maintenance.

Large tanks = large skimmers.

Hopefully, this guide was helpful and gave you some things to consider when choosing the right protein skimmer size. Take everything into consideration and not just one particular factor. For example, tank size. There are many different items that are worth considering. Once you compare the options, choosing the right one will be an easy task for you!