The short answer to “Do You Need a Skimmer?” is “maybe”. It really depends. We will get into that in a moment.
I have a love/hate relationship with skimmers. The hate part is pretty easy to explain. They are expensive, need frequent tweaking, frequent cleaning, they take up a lot of room, they are noisy, they smell, and if they aren’t working just right do next to nothing. For the cost a skimmer often seems a poor value when compared to the performance.
They are expensive
I admit, expensive is a relative term. For some people $300 is a lot of money. That is for a cheaper skimmer. This is especially true if you have just spend $1000 on lighting. It all adds up and sometimes when it comes to the skimmer we are at our limits already. Bigger tanks need bigger skimmers which cost more money. For example on the Bulk Reef Supply site you will find the “BUBBLE KING SUPERMARIN 300 PROTEIN SKIMMER” for $2,308.99. Yikes! Granted that is for a large tank. A heavy load of 500 gallons, a medium load of 845 and a light bioload of 1056 gallons. On the same site the cheapest internal skimmer (meaning in the sump rather than hanging on the back) is the “Eshopps IN-SUMP NANO PROTEIN SKIMMER” for $149.99. That’s not bad but that’s rated for tanks with a maximum size of 35 gallons. In my experience that makes it a good skimmer for a 20 gallon long but now think of that price compared to the tank size. It just kind of hurts.
Need Frequent Tweaking
As bioloads increase or decrease the skimmer works differently. As the water level changes skimmers work differently. I have even found that humidity will effect the way my skimmer works. All these little changes require you to tweak the skimmer settings a bit. Turn a knob here, lift it up there. That may not be a big deal to you but it is something to consider.
Need Frequent Cleaning
If a skimmer is doing its job you will need to clean it. Not only the cup but the body will need cleaning too. It’s another piece of equipment to maintain and clean. Depending on where you are in your house in relation to a water source this might be an annoyance. Skimmer cups are messy and smelly. If you top the cup and spill and you live with other humans you are likely to hear about it.
They Take Up a Lot of Room
Skimmer manufacturers have made significant strides in reducing the foot print of a skimmer but I have still found that the most efficient ones have a larger footprint. They can take up a big chuck of your sump. This also means that you might be limited in what kind of skimmer you can use if one rated for your tank size is too tall to fit into your stand. Always measure! The other kind of skimmer (not as efficient in my experience) is the hang on the back or “HOB” skimmer. which generally is hung on the back of your tank but can go on the side or front. It being on the back means that your tank has to be a certain distance from the wall. Always measure! They also detract from the aesthetics of your tank by having this thing hanging there. They tend to be less expensive but also less efficient.
They Are Noisy
Powerful pumps and a lot of air are what make a skimmer work. These both can produce a lot of noise. Sometimes, depending on where your set up they can also create a lot of vibration in your sump and make noise that way as well.
When you open up the skimmer cup you will find that the brown and gross stuff inside stinks. Think of it like your tank’s feces. Depending on your skimmer and your tank this smell can sometimes present itself even when the skimmer cup lid is on. Not ideal and not fun to deal with. The tweaking mentioned above is one thing needed to makes sure this doesn’t happen as is the frequent cleaning. I cleaned my skimmer cup out every other day on my 300 gallon tank.
Do Next to Nothing
We call them protein skimmers, which is accurate, but they also remove other things. What is removed by a skimmer is called “skimmate”. The protein part is in the form of dissolved organic particles generally known as organic carbon. But that is only about 40% or less of what is removed. Analysis done on skimmate shows second most removed item is calcium carbonate. Silicon dioxide, inorganic ions, and magnesium carbonate are also removed to lesser degrees. That means some things you would rather keep inside the tank gets removed as well.
That’s the hate part.
What about the love?
Now that I get down to this part I realize that the love section is significantly shorter than the hate section. I love that they do make your water cleaner and they can help you keep some livestock you might not otherwise be able to keep easily. There are some “mights” and “cans” in there.
They Make Your Water Cleaner
I have found that if I have cloudy water having a skimmer will help clear it up. So there is that aspect of “clean” as it removes particles. But that isn’t the main reason you get one and that doesn’t work all the time as it depends on what the suspended particles are.
What a skimmer really is for is for is to remove dissolved organic matter. If it is not removed then it breaks down into phosphates and nitrates etc. That is beneficial. It does it on a continuous basis. When you do a water change you also remove these particles but that only happens in the water you remove and only at that time. With a skimmer it continually pushes water through from all parts of the tank. That’s an impressive thing to have happen. How well that works depends on how well the skimmer works. I have found that not every brand of skimmer is equal. Even though, as I mention above, they all use the same basic principles, some do it much better. I’m a fan of Reef Octopus skimmers and have had the best results with them.
They Can Help You Keep Certain Livestock
When you remove all that stuff AND do your regular water changes you end up with very low nutrient water which is great for SPS and harder to keep LPS corals (and a few odd softies too). If your desire is to have that stony reef tank bright with branching corals, a skimmer will help you get there.
This is true of not only corals but other types of creatures as well. Keeping sea stars and urchins will be easier in a tank that is well skimmed. Sea apples, some shrimps, and more are better kept in a well skimmed tank.
But Do I NEED One?
This photo is of just what you think it is, three massive skimmers. The principles are the same. Lots of air creates lots of bubbles. The dissolved organic matter clings to the bubbles and is lifted up and out of the tank into the skimmer cup. You can size that up and down as needed.
The bubbles can be created with something as simple as an airstone and air pump like you see in many freshwater aquaria or with a specialized adapter on a massive return pump. There are many little variations but the principles are the same. An example of a very simple, and the most affordable off the shelf option, is this little skimmer designed for the BioCube. I’ve used this skimmer and it is surprisingly efficient given the size. However, one must replace the airstone frequently. In this case the stone is made of lemon wood so it isn’t an actual stone. This material is required to produce the very small bubbles that this skimmer needs to work. But as muck gets on the stone it stops producing enough bubbles to work. They don’t cost a lot, but they do cost and in this scenario they are kind of gross as they are coated with the protein.
Seeing that even large institutions use protein skimmers you may be temped to think that you absolutely do need one. Truth is though – you don’t unless (in my opinion and experience) you are keeping small polyp stony corals (SPS) in which case I highly recommend a protein skimmer.
If you are keeping fish only or soft corals you are actually likely better off without one. If you are keeping large polyp stony corals (LPS) there are some species that I recommend having a skimmer with. Learn about which of your corals are sensitive to high nutrient levels and that will help you judge. I mentioned that with soft corals a skimmer might be a detriment. I have found this to be true. Corals like mushrooms and xenia like to have those nutrients in the water and removing them can cause the coral not to thrive.
Need vs. Want – Conclusion
I always say there is a big difference between what you need and what you want. While I say you don’t “need” a skimmer I will say you likely do “want” one. I’ve had tanks with and without and tanks with poor skimmers. Even a poor skimmer performed better than no skimmer in terms of keeping nutrient levels down. If you are very diligent with water changes, or do daily ones (really a gallon a day is magic) then you can live without a skimmer. However, if you are like me and life sometimes gets in the way of tank maintenance then a skimmer helps keep things healthy just a little bit longer. Your tank is more “forgiving”.
Just go into skimmer ownership knowing it won’t be all easy going clean tanking that there are some considerations and you will be fine.