Red Cyanobacteria

Joshua I.

New member
Hi all Ive had a 55 gallon saltwater tank for several years now. Right now I have a fox face and clown fish and a coral beauty in it. At one point I thought about making it a reef tank and got some live rock. I decided not to take it a reef but left the rock which ended up having a lot of different hick-hikers on it. I didn't mind but ended up seeing this red algae all over about a year ago and its a pain to scrub off. Someone told me its Cyanobacteria so I got Chemi-Clean I was just wondering if any of you guys have used it. Are there side effects it doesn't mention and most importantly does it matter. By that I mean its a pain to clean but other than that it doesn't really bother me is it bad to just left it be?

Vinny Kreyling

Premium Member
There is red algae & there is cyano.
Red algae is really attached to rockwork & short haired like a green on a golf course.
Cyano is like a mat on the sand & can produce bubbles & is easy to siphon out.
Sounds like red algae to me but Chemiclean works for me when needed & I have a reef.
The rock is beneficial as a filter media & a tang like a Kole would be best for algae eating.


New member
If it is cyano all I done was keep sucking out when doing water changes and it's now one. I used some ro system tube.

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Joshua I.

New member
sounds like its defiantly cyan then maybe I described it oddly but it sounds like thats it because it everywhere but removes easily and has a lot of bubbles any benefit in leaving it do fish eat it or anything?


Well-known member
No fish that I'm aware of will eat it. I used to have problems with it when I was using fluorescent lighting. When the bulbs age their spectrum changes and that seems to promote it's growth. Incidental light from outside the tank (sunlight) can be another cause IME.

Remove as much as possible with water changes. Chemiclean will remove it, but it is really just a band-aid. You very likely have an excess of nutrients feeding it. Clean the substrate thoroughly. A Python Siphon will work wonders for that. IMHO it is a must-have piece of equipment for all aquarium keepers.

Michael Hoaster

Registered Seaweedist
Premium Member
For cyanobacteria I like to do a combination of actions to weaken it first, then deliver a knock-out blow. Start with manual removal on multiple days. Then unleash the chemiclean AND a 3-4 day blackout. Wrap the tank to seal out light. Finish with a water change/vacuum to remove any traces.

Increase water flow rate in the affected area. Cyano likes low current. Consider adding plants to your system. A red macro algae like Gracilaria can adjust to different nutrient levels. I've seen Mollies eat cyano, but you need a lot to make a difference.