Growing macroalgae in your aquarium as part of your filtration system can prove to be very beneficial. Macroalgae such as chaeto can help with nutrient export, gas exchange, providing a habitat for copepods, and cleaning the water of harmful substances. Certain kinds of macroalgae can also be used to feed algae eating fish. It is most commonly used for nutrient export, but even if you need no help there, macroalgae can assist in those other areas as well.

 

 

The goal when keeping macroalgae is for it to grow. Unless you are running a "planted" saltwater aquarium, this is not for aesthetic purposes. Instead, it is for all of the reasons mentioned above. When macroalgae grows, it means that it is consuming nutrients, exchanging gas, cleaning the water, and providing more space for copepods and other microfauna to live. if the macroalgae is not growing, then it is unlikely to serve its purpose. Knowing about how to provide adequate care for macroalgae is important. It is equally as important to be able to tell when the macroalgae is not doing well and how to fix the problem.

 

In this article, we will be specifically talking about keeping macroalgae and some possible troubleshooting. If you are panicking because your chaeto seems brittle or like it is crumbling, you are in the perfect place!

 

 

Before worrying about more specific and less common problems, make sure your macroalgae is receiving the fundamental care first. While there are a lot of requirements macroalgae need to grow, these requirements are usually met in most reef aquariums. The two requirements that can easily not be met are lighting and nutrients.

 

When it comes to lighting, there is a wide range of options. There are refugium lighting options that cost hundreds, while there are others that can be well under $100. Are the more expensive options worth it? Like a lot of things in this hobby, it depends. A lot of the higher end refugium lighting options are used to light large refugium. If you have a large refugium, it is certainly worth it. Still, there are some expensive options that can be used for smaller refugiums. Generally, the higher price range the light is in, the better it is going to grow macroalgae. The AI Fuge 16HD light, for example, can be used on a wide range of refugium sizes, and it can be controlled from your phone. It is one of the best lights for growing macroalgae. There's also the ChaetoMax from Innovative Marine which is one of the cheaper options. It has no controllable functions other than on and off and no timer built in. Then, there's Kessil which has the widest range of refugium lighting options (check out this one and this one). Kessil is one of the most popular and well-established refugium light companies and is certainly a good option. However, the AI Fuge 16HD should still be given heavy consideration for its controllability. So, those are some recommendations, but what makes a refugium light different than a normal reef light? Well, algae prefers lighting with lots of red spectrum output. It is possible to grow macroalgae under normal aquarium lighting, but it will grow much faster with a refugium specific light. If you have a good light such as one from Kessil or AI, you can probably eliminate that as a problem.

 

What is more common than poor lighting is low nutrients. As you probably know, one of the most important things for algae to grow is nutrients. That applies to microalgae and macroalgae. High nutrients such as nitrates and phosphates are the most common reasons hobbyists have algae problems in their aquarium. The difficult thing is that nutrient levels can read near zero, but still be present in the aquarium. This can happen because the microalgae (that bad algae) is consuming the nutrients as soon as they become present. If your levels read zero, but you are still having algae problems, this is likely why. To combat this, you need to physically remove as much of the algae from the display tank as possible, which allows your macroalgae to consume the nutrients instead of the microalgae. Doing this gives the macroalgae an advantage over the microalgae. If your tank is free of microalgae in the display and the nutrients are low, this likely means that the nutrients are actually low. This is usually a good thing, and it means that your other nutrients export options are working well. At this point, macroalgae may not be needed (unless it is the reason the nutrients are low). However, if you want to keep macroalgae for other reasons, you can dose your tank with some kind of macroalgae fertilizer, or you can simply feed more and maybe even add more fish. Who doesn't want that?

 

Having nutrients that are too low is usually because the microalgae is consuming them. Having low nutrients simply because they are being exported by equipment or being consumed by corals tends only to happen in mature aquariums. Even then, it is rare.

 

 

If you have your nutrients and lighting covered and you are still seeing brittle or dying chaeto, it is time to take a deeper look.

 

Something that is usually not a problem but is still important is water flow. Most sumps and filtration systems have enough water flow through them to stop the macroalgae from choking out. If the water around or inside the ball of chaeto becomes stagnant, the macroalgae will essentially start to starve. It might not be able to get enough nutrients or carbon dioxide. If it seems like the flow around your macroalgae is weak, you may need to add some more flow. The most common way to do this is to add an air pump. Air pumps have no intake in the water for the algae to get stuck in, making them the ideal solution. You can use a power head if you want, but know that you may have to clean it frequently.

 

Another factor that is often looked for macroalgae is salinity. Although macroalgae is hardy, keeping a stable salinity level is important. Keeping your salinity stable is important for the whole system, so this is a must. Make sure you use an auto-top-off (ATO) system to help keep the salinity from fluctuating. If you are going to use an ATO, place it after the refugium, preferably in the return section because that is where the water level will fluctuate most of the time. Avoid adding freshwater into any section before the macroalgae or in the same section as the macroalgae.

 

The final thing we will talk about is harvesting your chaeto. Chaeto, and macroalgae in general, is not something you add to your refugium and forget about, especially if you are using it as nutrient export. Macroalgae needs to be harvested from the refugium once it gets too large. A lot of hobbyists do this biweekly and remove 20-50% of the macroalgae. How much you need to remove and how often depends on the growth rate of the macroalgae and how large your refugium is. The reason this is important is because macroalgae can grow so large that it starts to cut off other portions of it from flow, light, and nutrients. This will cause large portions of the macroalgae to die, which will release the nutrients back into your aquarium. Having a lot of macroalgae growth is excellent, but you need to harvest it. Having to harvest your macroalgae frequently is a sign that the macroalgae is healthy and removing a lot of nutrients. That's a good thing!

 

What do you do with the harvested macroalgae? There's a few things you can do. If you have some reefing friends, especially new ones, you can offer it to them. Depending on the kinds of macroalgae you are growing, you can feed small amounts to your fish. Fish will not eat chaeto, but they love ulva macroalgae also known as sea lettuce. You can harvest your algae slowly by removing little bits everyday to feed your fish. Other than that, you can simply throw away your macroalgae. If you keep a compost pile, it can be put in there.