I think of cheato like a hydroponic plant.. I had problems growing it long ago, until I began using my knowledge in that area.. Simply overpower it, and it will grow.. The nature of a plant is to put energy either into growing, or producing offspring.. And it needs sufficient light power and photosynthetic energy to do so.. And a plant will scavenge nutrient, as long as it has the energy to do so. All of which requires light energy..
There are a few things I have discovered over the years, at least for myself when it comes to growing it, but still using hydro principals..
You simply have to think about what your trying to do. Your attempting to "grow" a vegetative plant(your growing to grow only and maximally), so generally speaking, your going to, as another person said, need to up your hours. At least 16 hours up to 22. That is, even with higher powered lighting,which is the next thing ..
And I'm in the minority by far on "more power", but the results speak for themselves.. The Kelvin definately matters, but so does the wattage and "type" of bulb.. An incandescent 150 watt bulb simply, at the same power, doesn't have penetration power of say a hid type of bulb. And though cfls(especially the mogul based ones) are stronger, they still do not grow like a small hid bulb.. Or even better yet, as I found recently, a dedicated horticulture led fixture..
As far as scrubbers(and the ARID reactor) , the one thing that most don't realize, is that all your doing is bombarding a small area with a ton of light and sufficient contact with flowing water.. It will do it's own thing at that point.. Same principal with cheato growth "should" be employed. But.. Unfortunately it is not.. There really is no need to dose anything, and no need to tumble.. That is, unless your light doesn't have the power to do the job. Which, is, a lot of the problem with cheato growth with most.. And you once again "can have low nutrients and still grow cheato well".. My last 3 tanks have been sps dominant, and always has low levels, but I have always been able to effectively grow cheato.. And by affective, I mean I measure 5 gallon bucket full time frame, simply because I use it as a co2 scrubber also.. You just have to overpower it(and your display tank so that the majority of the light energy is going towards the fuge)
But, my suggestion, throw more light at it.. Buy a horticulture led(at least 120 watt) grow fixture, run it 15 hours and watch it explode.. The pictures attached are my typical growth for less than a week after a harvest, and I have a 4 foot 75 as my sump, so it's not huge(also is my eel den)..
And the cyano, is from the spectrum of the CFL.. It's the spectrum of the bulb.. I had that issue with both the 2700 and 5000k large mogul CFL bulbs(100 and 150 watt).
