Very interesting video. I don't know if those diatoms have anything to do with the cyano but I would bet they are just living in the same type of environment that has beneficial conditions for both.
I had cyano growing in my tank and after getting my new skimmer it all went away in less than a week. No more cyano, gone, totally.
I think the most important factor for cyanobacteria to thrive is dissolved organics (DOC). Even if you have low nitrates and low phosphates you still can have cyano if you have any DOC in the water. I don't think there is a way to mesure the amount of DOC In the water...maybe with an ORP probe? not sure.
My new skimmer is pulling the same amount of skimmate in one day that the other was pulling in weeks. So now my water is deprived of DOC and the cyano simply died. I beleive that if someone has a cyanobacteria problem then it probably is due to the skimmer not being efficient enough for the bioload. In my case it could be a coincidence but I have not change anything else and my nitrates and phosphates are still quite high, so that's not it either.
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http://netclub.athiel.com/cyano/cyanos2.htm
- Any of the conditions that adds organic compounds to the water exists in your situation and probably more than one is at work, not just a single one. When water chemistry gets out of hand, the causes are more often than not, multiple.
- The skimmer removes "some" of this dissolved organic material but more is actually produced than the skimmer is removing. This is a very common occurance. Either the load is high or the skimmer too small, or both. In either case, DOC will start to build up.
- Given enough time, the amount of dissolved organic material reaches a stage and a concentration where the amount present starts giving rise to the appearance of red slime algae because there are now enough nutrients present to allow this growth to occur. In this respect you may wish to consult "Organic Chemicals in Waters" James W. Moore and S. Ramamoorthy, Springer Verlag, 1984, ISBN 0-387-96034-1 (cost $50.00).
- When the increase continues more and more cyanos will grow since what is being removed is less than what is added to the tank water.
- This accounts for the growth that seems to rapidly increase once it takes off even though you may be siphoning algae out and changing water.
- It should be noted that the slime produced by these cyanobacteria is just about pure organic material and decomposes, adding more organic matter to the tank.
- Of course the amount that decomposes is replaced by a new sheath of slime, and the process just continuous on and on. One dies off and decomposes, adds organics to the water, and immediately a new one develops underneath (and at the same time) that soon dies and adds more organics, a new one grows, etc. You get the picture. DOC keeps rising and rising.
- Organics are not the only matter involved in the growth of blue-green algae (Cyanobacteria or red slime or whatever else you want to call it actually). Iron is another nutrient, but to a lesser degree than DOC or dissolved organic carbon (organic material dissolved in the water). I mentioned an interesting book earlier. Another easier one that you may wish to read or perhaps refer to if you can find it at a library is: "Inorganic, Organic and Biological Chemistry" by Philip S. Chen, Second Ed., The Barnes and Noble Outline Series, 1979. ISBN 0-06-460182-x (originally published by Harper and Row).
- Those of you who have dealt with red and other slime algae have gone through this and know exactly what I am talking about.
- Once the growth of red slime algae starts, rapid intervention is necessary or the whole tank will soon be covered with them and the growths will choke what is underneath, often killing life forms. Life forms that die off then lead to more decomposition and more organic matter being added to the water.
In essence, what I have found is that when the amount of dissolved organic matter builds up to a high level, sooner or later (usually sooner than later) red slime or blue-green algae will start to grow.
The key then, is to keep this amount low. This is achieved through skimming but may need to be supplemented by other means, especially if you have red slime algae present in the tank already.
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