The Top 9 Biggest Reef Tank Myths

The Top 9 Biggest Reef Tank Myths

There are still so many myths about reef tanks floating around - we are here to share light on some of them.

You finally made your decision: you want to buy a saltwater tank. Great! Now, you’ll probably start combing through forums, blogs and social media for information and experiences by other aquarists. What do you actually need? What are the demands of stony corals? How much light do soft corals need? There are plenty of questions that come to mind when you start, and thanks to the internet, you’ll get just as many answers. But be careful – sadly there are still a lot of persistent myths going around that are sometimes just wrong and sometimes even harmful.

In this article, we gathered nine of the biggest myths about saltwater aquariums for you:


#1: A saltwater tank is expensive

Yes, having a reef tank can be an expensive hobby. But good news: you have considerable freedom of design and don’t necessarily need to spend a lot of money for your tank. You can build a beautiful aquarium even with a “smaller” purse.

Before you start buying the necessary equipment though, here’s our tip: make a plan about the type of aquarium you actually want. Ask yourself different questions such as “Does the equipment need to be super quiet?” or “What animals do I want and do they need a bigger tank?” or “Do I really want to buy the colorful Acropora corals that come along with high-quality (and probably more expensive) lighting?”. Those questions help you find the right things for your dream aquarium.

Another tip is to buy second hand. You can find a lot of good, high-quality equipment in social media groups or on different platforms. It’s no problem to buy used skimmers or pumps; just be careful with used glass tanks, lighting systems and heating elements – look twice here or buy new ones.

Once you own the necessary equipment, here’s even more good news: you’re allowed to build your reef up slowly. Decorations, fish, corals – you don’t have to buy them all at once. Fill up your tank a bit at a time and stretch the costs over a few months.

And our finally tip: you don’t have to buy the rare stony corals – buy soft corals and few (or no) fish. That minimizes the need of consumables (such as balling salts), makes it easier to maintain your tank and looks beautiful nonetheless.

Coralaxy Aquarium 

How expensive your tank actually will be, is often up to you and your wishes.

#2: A nano aquarium is easier for beginners than big tanks

Small aquariums or so called nano aquariums have become more and more popular in recent years. Beginners are particularly interested in them, hoping that the smaller tank size makes for easier care and maintenance. But does a smaller aquarium really guarantee less work?

Sadly no. Often times, the opposite is the case. A small tank needs just as many water changes and just as much care as a bigger aquarium. It is often more difficult to stabilize important parameters (such as alkalinity, calcium, etc.) in these small systems. Water parameters can change rapidly due to the smaller volume and cause a series of problems. A bigger water volume gives you more time to see those problems and take action.

We don’t want to scare you away from nano aquariums. Just remember, that a smaller tank size does not mean less work.

#3: The more light, the better

Corals that grow in shallow areas of the reef (close to the surface) are subjected to a lot of light. So it’s only logical that those corals need just as much light in your saltwater tank, right?

Yes and no. Corals need light for their growth, coloration and photosynthesis – but too much light can inhibit these processes and cause the so called “light stress”. That’s due to their zooxanthellae – the small microalgae that live within the tissue of the corals. These algae live in symbiosis with the coral and provide them among other things with energy. Too much light for the zooxanthellae quickly leads to the saturation of the photosystems and the excess energy causes the development and release of oxygen radicals. Oxygen radicals are oxygen-containing molecules that can cause damage to the cells. This phenomena is called “oxidative stress” or as the aquarists say: “burning”. To avoid oxidative stress or keep it to a minimum, many corals develop so called protection pigments under strong lighting conditions. These pigments can absorb or reflect light. Subsequently, the corals have less energy for growth and other physiological processes though. This only shows that very colorful corals are therefore not always the happiest and healthiest corals. Here it’s important to provide them with enough nutrients and trace elements.

In natural reefs, you can find corals in depth up to 100 meters. The lack of light in these depths is compensated through catching plankton and detritus. Even though the need of light differs among the species, the corals can adapt to certain conditions.

It’s important that you research the lighting needs of your corals beforehand. This way you can either change the lighting or place the corals inside your tank accordingly.


#4: Stony corals need more light than soft corals

And while we’re on the subject of light, here’s the next popular myth: stony corals need more light than soft corals.

To keep it short: there is no scientific evidence for this. In natural reefs, stony and soft corals grow equally close to the surface (=in an area with much light). Once you dive deeper, you can see the same thing. Even various scientific experiments could not prove this myth to be true.


#5: Blue light is the better option for corals

Many aquarists love their bluelight-flooded tanks where their corals shine in their brightest colors. This sort of lighting is definitely easy on the eye – but it doesn’t necessarily mimic natural conditions.

In the ocean, almost all light colors reach depths up to 5 meters. Only if you dive deeper, the red, orange and yellow color portions of the light are slowly absorbed and the light spectrum shifts into the blue area.

If you want to use blue light for your saltwater tank, you should keep in mind that it’s much more intense for your corals. To avoid light stress, you should provide them with enough nutrients and trace elements. Blue light provokes the production of protection pigments and makes your corals look much more colorful. The natural light spectrum (or the light spectrum close to the surface) contains more red and green color portions. These are important for photosynthesis processes for the zooxanthellae and eventually for the energy supply for the corals. If you only use blue light, we therefore advise you to feed your corals with plankton, frozen or powdered foods. This can help balance out possible energy deficits.

What lighting system you use in the end, is more often than not a question of personal taste: do you want a more natural reef look or do you prefer the look of strongly fluorescent corals? In case you go for blue light, we don’t recommend leaving out red and green color portions completely though. Maybe you could combine a daylight- and bluelight-phase during the day.

Corals under bluelight

Blue light lets your corals glow - but is it always the best option?

#6: The more water flow, the better

Yes, water flow is an important factor when it comes to the correct care of your corals. It’s important for gas exchanges, prevents sedimentation build-ups, and provides your corals with enough particular and dissolved nutrients which in turns has a positive effect on the growth of your corals.

BUT: don’t overdo it! No coral wants to sit directly in front of a pump. Too much current can cause damage to the polyps or tissue. While some corals prefer a stronger water flow (e.g. Sarcophyton, Stylophora & Co.), others prefer quite the opposite (e.g. Plerogyra, Discosoma & Co.). Watch out for soft corals, mushrooms, Zoanthus and large polyp stony corals (LPS) – many of them don’t care for a strong current.


#7: Trace elements are necessary for healthy and colorful corals

There are thousands of trace element solutions available to buy. Single trace elements or combination solutions – whatever you wish for, you will probably get.

Trace elements can be helpful and their effectiveness in biological systems is proven – but it’s not always necessary to put them in your tank. Often times, the trace elements brought into the system by regular water changes, the calcium supply, and feeding are enough to keep the parameters stable inside your tank. Depending on the stocking density, providing your corals with additional trace elements can lead to an overdosage. Especially in the beginning, when you don’t have many corals in your aquarium yet, it often makes no sense to dose more trace elements – because you can quickly get a problem with unwanted algal growth or the mass occurrence of cyanobacteria. However, if your corals show deficiency symptoms or growth problems, trace elements can help. To avoid an overdosage and make sure that there really are not enough trace elements in your system, you should test it beforehand in a lab, using the ICP method. There are many labs which offer that service to (hobby) aquarists.


#8: Form and color are good criteria to determine corals

Sadly, that’s not the case. Form and color of a colony can change depending on the environmental conditions. For example, corals that are subjected to a strong water flow, develop thicker branches and a stout build. Even the skeletal structures inside a colony can vary, depending on their position/exposition.

Just like the build, the colors can also vary quite a lot. Light intensity, light spectrum, availability of nutrients and trace elements influence the coloration strongly. On top of that, there are always different color morphs, depending on their genetic composition.

So, there are a bunch of reasons explaining why the correct determination of corals is often a tricky task. To be certain, you need information about their skeletal structure, genetic composition, and bio-geographical origin.


Determing corals is often more difficult than it seems at first glance.

#9: A reef tank without a skimmer does not work

To get to the point quickly: no, a skimmer is not always necessary! – However, it does make a lot of things easier. Most aquarists use skimmers nowadays but there are alternatives to remove nutrients, unwanted compounds, residuals and decomposition products from your tank or prevent their development in the first place.

A good mechanical filtration (e.g. filter floss or fleece filters) removes a lot of particular materials already. Using activated charcoal on top of that helps with removing unwanted compounds such as yellow substances, toxins, or nettle toxins. The same result can be reached with regular water changes (weekly between 5-10%).

Biological methods can also replace the tasks of a skimmer. Examples are the Deep Sand Bed (DSB) or an algae refuge.

A DSB basically consists of a high substrate (at least 10 cm), made out of fine aragonite sand. The height of the sand makes it possible for areas without oxygen to develop, in which anaerobe bacteria live that remove the nitrate from the system.

With an algae refuge, aquarists use macro algae inside their system. They are often placed in a separate area inside the technical tank. Nitrogen and phosphor gets fixed by the algae through growing and is removed by regular harvest of the algae.

Compared to skimmers however, the effectiveness of these methods is hard to pin down and even harder to control.

We always recommend using a skimmer since it has no negative effect on your tank (exception: nutrient deficiencies!). If you have fish, the skimmer helps you provide them with crucial oxygen.


This concludes our article about 9 of the biggest reef tank myths. We hope this article helped you a little! If you have any questions, you can always contact us. Until then – Happy Reefing!