I have been battling a moderate cyano outbreak for the last several months. I am at wits end! I lost a large sarcophyton a couple of months ago - this appears to be the beginning. Is it possible that the contaminants are still hanging around. I have replaced about 80 gallons of water since then. To date I have changed and verified my RO/DI  cartridges. TDS = 0. I have replaced MH bulbs (Jan) I have replaced VHO bulbs (Apr). I cannot figure out what is causing the cyano.  HELP! HELP! HELP!

125 gallon, RD refugium in sump, skimmer (24/7), ~75 lbs LR, LS/DSB w/ plenum, 2 x 175w MH, 2x140w VHO.

Tank has been up and running for over 3 years. What next?  

Is that the yellow powder in the little bottle?  My neighbor has (still has) a cyano problem.  He used that stuff and it did clear up but only for about a month, then came right back.  Subsequent treatments have not helped (have possibily hurt).  I think what he's using is an antibiotic which kills not only the cyanobacteria, but also the nitrification/denitrification bacteria.  After the second dose he had an ammonia spike (killed some fish) and the tank re-cycled.

Has anyone else had this happen or did something unrelated happen to my neighbors tank?

One thing I've thought about with regard to cyano, is to try to get hair algae to outcompete the cyano (you'd be trading red for green), by dosing iron (and maybe nitrogen, NO3) in the tank.  Then work on getting rid of the hair algae (hard skimming, tangs, snails, macro algae).  I wouldn't really recommend this, just free flowing my thoughts :).

I had this crap also, I reduced my lighting, not by me wanting too.  I had a Lime Wrasse who was having a difficult time with his reflection, he broke two metal halide bulbs in about a month, so I had my main day light off for a total of seven days.  The combination of the light reducation and a five gal. water change a week has made this stuff disappear.  I now do a 5 gal. water change every two weeks.  I have a 54 gal.  I hope this information helps.

Have you tried increasing your water movement.  This will usually wipe it out.

Increased water flow will help alot and sand shifting stars will help move the sand around to help keep it from coming back...

Ryan

www.marine-aquatics.com

Determine what is feeding the cyanobacteria (source of excess nutrients) and stop it or remove it! Sometimes no feeding for five days and then feeding less will control it

Fish food, detritus hanging around, etc.

Insufficient consumption of nutrients in the RDP Sump will ALWAYS lead to algae growth in the main tank. (algae types, insufficient illumination, nutrient buildup, detritus buildup, if sand in the sump has never been exchanged with someone wanting live sand, etc. 

TPF has some abalone, yesterday they showed me is eating up their cyano! It's a neat looking mullusc too!

Keep trying Shane, I'm confident you'll get it under control.

When i had my first Cyano outbreak in my tank I thought I had read that cyano actually had algae in its cells.  Here is a rip from some webpage talking about cyano.  Seems it can create its own food.

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Cyanobacteria are aquatic and photosynthetic, that is, they live in the water, and can manufacture their own food. Because they are bacteria, they are quite small and usually unicellular, though they often grow in colonies large enough to see. They have the distinction of being the oldest known fossils, more than 3.5 billion years old, in fact! It may surprise you then to know that the cyanobacteria are still around; they are one of the largest and most important groups of bacteria on earth.

Many Proterozoic oil deposits are attributed to the activity of cyanobacteria. They are also important providers of nitrogen fertilizer in the cultivation of rice and beans. The cyanobacteria have also been tremendously important in shaping the course of evolution and ecological change throughout earth's history. The oxygen atmosphere that we depend on was generated by numerous cyanobacteria during the Archaean and Proterozoic Eras. Before that time, the atmosphere had a very different chemistry, unsuitable for life as we know it today.

The other great contribution of the cyanobacteria is the origin of plants. The chloroplast with which plants make food for themselves is actually a cyanobacterium living within the plant's cells. Sometime in the late Proterozoic, or in the early Cambrian, cyanobacteria began to take up residence within certain eukaryote cells, making food for the eukaryote host in return for a home. This event is known as endosymbiosis, and is also the origin of the eukaryotic mitochondrion.

Because they are photosynthetic and aquatic, cyanobacteria are often called "blue-green algae". This name is convenient for talking about organisms in the water that make their own food, but does not reflect any relationship between the cyanobacteria and other organisms called algae. Cyanobacteria are relatives of the bacteria, not eukaryotes, and it is only the chloroplast in eukaryotic algae to which the cyanobacteria are related.

I had a bad cyno out break, covered everything. I added activated carbon, every week and regularly cleaned out my filter floss every week. When I had my out break my skimmer wasn't even working. Just using carbon and clean filter floss in my sump helped alot. I also limited my light. Good luck. Nigel

I had a minor out break of this but jumped on it as quick as it started.

The quick solution in my opinion...is Chemi-Clean!  Its a white powder in a small bottle with spoon included for doseing the tank.  Its truely a effective 24 to 36 hour cure for sure, but requires a 25% water change afterwards if memory serves me correct!  I have not had a problem since.

I do believe this is a bandaid on a cut throat though.

Sounds like you have a nutrient rich water problem.  This is purely speculation though.  I did feed very sparingly since.  I have added more live rock, more plants and added more crabs and havent had an out break since

Just food for thought....