tmz said:
That's not clear at all. If it's a magic number how do you get to it. The whole argument is nonsense wihout a point or clear position.
You refuse to let go of the idea that I've been making an argument in favor of some specific aquarium management regime when, in fact, I'm trying to describe the way things work so that other hobbyists can make their own decisions about how they run their own tanks. What I said was, "Cyano blooms are all about PO4 -- and looky here, some FW guys caught on to this years ago, and their tactic of N-dosing is consistent with the model I've just presented." ...but you insist on reducing that to, "You should dose N if you have cyano."
The way things work is complex.
[Mod Edit: Personal attacks not welcome] I mean, I haven't even brought up the fact that a mature cyanobacterial mat is a phosphorus pump that puts P
into the substrate rather than pulling it out...
And in any event, I'm into bioremediation -- hence my interest in cyano scrubbers and DSBs -- and do not like to mess with water chemistry beyond two-part homebrew dosing and some supplementary Fe to keep my algae scrubber in good working order. However, I recognize that there are multiple successful strategies for running a marine aquarium, and I assume that hobbyists who
do like to mess with water chemistry neither need nor want an amateur to hold their hands.
tmz said:
It also includes a reference to the lyngbya species which is absolutely nothing like the red slime algae most salt water aquarist experience. I've actually seen it in a reef tank .
Oh, so now I have to explain the red plague, do I?
No problem. Took me about 20 minutes on a quiet Saturday to find the answer that has apparently been eluding hobbyists for years.
Red slime isn't a specific species of cyano -- rather,
it's a common response by cyano to ambient light conditions known as chromatic acclimation. When this phenomenon was discovered over 100 years ago, it was called "complementary chromatic acclimation" because it was observed that cyano shifts its color towards the complement of whatever color of light it's growing in. It was originally observed in red/green lighting conditions but in recent years has been documented with other colors -- including the blue hobbyists favor in our high-color-temperature DT lighting.
That is, blue (and also green) light makes cyano turn to reddish photopigments to get more energy from photosynthesis: "In blue light, these cells have a relatively high ratio of the blue-light-absorbing chromophore phycourobilin [PUB] to the green-light-absorbing chromophore phycoerythrobilin [PEB]... These changes in the the PUB

EB ratio change the color phenotype of these cells between orange and pink."
Further, "The ability to carry out CA [color or chromatic acclimation] is not restricted to a single branch of the cyanobacterial lineage. It occurs in all major groups of cyanobacteria and is not strongly correlated with any particular environment, but rather is a geographically widespread process... The capacity to undergo CA is present in a wide range of species and environments and is likely to make a significant contribution globally to maximizing the efficiency of photon capture for photosynthesis."
Thus, it doesn't matter what species of cyano is involved -- blue light = red slime