Manganese interferes with PS1 & PS11 to kill cyano or more corectly to stop it living. It stops the organism from producing light gathering pigments lost during normal photosynthetic activity. Chlorophyll A etc are the colored 'bits' in the zoa that give it the 'brown/green' color.
So if we can inhibit a specific process that will only do two things in our reef without adversely affecting anything else and those two things are:
1. control cyano completely and problem algae to varying degrees.
2. regulate how light or dark the zoa are without decreasing their number so as to maintain healthy nutrient transfer to corals.
Number one sounds good for obvious reasons.
Number two means less chlorophyll light shading so the acro is 'forced' to produce more protective pigments now that you have made the zoa less efficient at producing chlorophyll. As long as the nutrition drop from less photosynthetic activity in the zoa is replaced with water borne nutrition and required elements for pigment formation are present i believe you can produce good results.
That's the basic idea of what i believe is happening in my almost 3 month experiment.
Nothing but feeding fish and no water changes and nothing else, no skimmate, roids - nothing but a skimmer, cup of carbon in a bag in the sump and 16L matrix.
I have tried very hard to limit variables over the 3 months and you all know exactly what the only chemicals are i'm using in a once a day dose. I'm swapping the trace hard for Replenish this weekend since many find it hard to get Salifert trace hard. I'm confident it will do the same job because the ratio of iron to manganese is much less than the ratio in sea water and iron limited with manganese is exactly what i want, not no iron because it's essential but just enough.
This is where it all started, i was trying to figure out why cyano was no longer a problem.
Thanks very much Mark