Myth Busting. Is algae filtration safe and right for your reef aquarium?

by Richard Back 

My aquarium utilizing algae scrubber filteration (algae picture provided by Joey Olive of 302 Aquatics) and macro algae and media reactor filled with chaeto from Kris Cline of Carolina aquatics .  

​There has been some debate online about using algae as form of filtration is actually not safe for our aquarium. To talk about this, we went to visit a guru that we all know, love and respect. Julian Sprung of Two Little Fishies in Miami, Florida.

Julian, there has been ongoing talks online saying that algae releases toxins that are bad for our reef aquariums so that it’s not recommended that we keep algae in large quantity. What are your thoughts on it? 

(laughs) as you know from looking around my aquariums, I use algae to filter my aquariums to quite an extent. So if algae released toxins, I would be concerned about it. (laughs) Truth is that they do. They leach substances called leachate and if you have a rhizome of caulerpa growing across the coral, you can see the coral tissues get damaged. 

Uh oh. Is algae only thing that releases harmful substances in the water that can be harmful for inhabitants of our tanks?

 Any creature, whether it is sponge or coral, creature living on the reef, they emit substances in the water that are harmful to their neighbors because it is a battle for territory. Algae is no exception.
They will release things in the water and even bacteria will release things in the water. 

How did this come about?

​A lot of substances that are released by algae, we refer to them as D.O.C. (dissolved organic carbon) it may be simple sugar or more complex organic substances and there is a researcher whose name is Forest Rohwer and he is out there in San Diego. He is world famous researcher who studies in microlobulations in seas and on coral reefs, he looked at microbes, bacteria and the viruses that can be found on reefs and what he found on reefs, where algae are high stock, large standing stock of algae, where it is shifted more towards algae then the corals that is a cascading effect because as algae become dominant, they release D.O.C. and you can measure it in the water. He has been able to say that if you have this organic carbon in the water then we will find certain microbes in the water, corals will get disease, they will die, and it’s tied with algae and organics. Hearing this and reading reports he’s written on it, you might say hey, wait a second… but I keep and grow corals in aquarium and I’m using algae as an algae filter and the corals are thriving! That’s an contradiction or maybe you have a reef aquarium and you have been carbon dosing. Whether you are adding vinegar, glucose (sugar), methanol or any of these organic substances that people add to control nutrient levels and corals are thriving and not going downhill.

So how does Forest’s findings affect our aquarium hobby?  

I don’t mean to discredit what Forest Rohwer is talking about. What I’m trying to say here is that it’s much more complex than black and white issue to say that algae is bad or dissolved organic carbon is bad. It really gets down to what is actually happening. There is lot to be studied. I think the contradiction is kind of thing that any scientist like myself would look at and say "wow! This requires more study."  To really understand what is the process that the Forest has discovered and illuminated on the reef and what makes it work that way and why it isn’t the same process happening in our closed system aquarium. It would be neat if he can be introduced to the aquarium hobby and understand that what it is that we are doing and tie it down with his own research.

What is your personal opinions on algae filtration?      

I think it’s wonderful way to control the nutrients in the aquarium.

It also modifies the respiration effects in closed system. (Soak up the C02, raise the pH) 

---

Huge varities of macro algaes in refugium.  Pictures by Hernando Rocha. 

​​
Thank you very much Julian for sharing your knowledge with us!
Although there is truth behind harmful release by plants, I think it's safe to assume that it's safe to be used in our aquarium to be effective tool to handle nutrients as well as keeping pH and oxygen level up at night time. 

So fellow reefers, have no fear and utilize algae as method of filteration if you were considering it to using it to help you control your nutrients! 

Be sure to look out for the video that will be coming out shortly with all this information plus more!

​Happy reefing!