cyano is a deal that behaves like algae, regardless of its proper classification.
i always suggest to take a hard look at what is going into your system. food is number 1 fertilizer. cut back all food by 50% for a couple months and see how that does. people treat their fish like they treat themselves: rampant overfeeeding
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lean fish live longer anyway...
anyway, THEN once you have cut back on nutrient input into your system, look at how you can increase export of nutrients. keep after the skimmer better, cut an hour off the lighting cycle, harvest algae at a reasonably consistent rate. (i made a dedicated algae tub for myself to grow algae better than in the DT and it is easy to harvest/scrub the rocks). Siphon crud when you do waterchanges vs just siphoning from the water column.
turkey baste the rocks to keep stuff from settling and creating nitrate sources. and so on.
btw, i agree, that just the fact that the tank has life of any kind is a good enough excuse for algae to grow. my tanks have been idling for like 3 years now..burning out Valonia spores. but it has been interesting to watch the algae in a 100+ gallon system with no CuC, 1 fish and sparse weekly feedings. the nutrient levels are way low, yet certain algae like to grow in certain places. and believe it or not my skimmer still pulls foam.
I also have little doubt that waterchanges are replacing something that the macros like, because macros sprout after waterchanges every time. the micro garbage seems not to care. i may have to take some pics of what the "prairie" looks like on really old rocks with minimal algae disruption(except for the blenny who doesnt eat calcerous little macros anyway) over several years(except for valonia patrol and HA scrubbing when it was needed)
