Theoretically you are absolutely right, however I have also heard that water changes can sometimes feed algae even if the water is "clean", i.e 0 on Nitrate and Phosphate, the theory being that there are other substances or minerals that come with the salt mix that are also feeding the algae. Not sure which substances or minerals these are supposed to be or if true but I have heard that before.
What frustrates me about this hobby is that there are so few definite answers and that so much ofit seems to be pot luck, such as someone having a perfect tank for years, nothing changing and then suddenly getting explosions of algae... we need more proper scientific reasearch and analisys so we can properly understand what really drives these suddend changes. Still love it though!
Humm.........I think it has less to do with the salt mixes and more to do with the disturbance and flow during the water change itself, it kicks up detritus from places that have not been cleaned out for sometime.
We tend to have a lower O2 level and the subsequent rise in CO2 as result of bacterial action on the detritus, then the nutrients follow.
I suspect noxious algae are able to respond to this group of changes.
So rather than limiting ranges of ppm's or ppb's, it has little to do with limitations like Liebig suggested for plant growth growth 160 years ago.
It's not nutrient competition in otherwords.
Let say this, I have lower Mg and also much richer N and P levels, and yet no issues with noxious algae.
That is a "reference", eg an aquarium lacking the noxious algae, yet having the supposed hypthetical algae inducing Evil nutrients.
Such aquariums falsify these hokey myths about nutrients and algae blooms.
It does not answer why the algae bloom, but it does illustrate what it is "not" in and of itself. So that is a much better bit of info that speculation, dogma and myth.
So that is another way to approach the questions and problems.
Once you rule out most of the main players that seem most likely, then you are left with only a few choices(generally/hopefully).
Ruling things out can be done fairly well by good seasoned aquarist.
I think some higher Mg seems to help, but I'd need to know what induced the Byropsis to germinate and recruit to a rock etc to begin with. I'd need to be able to do so that the methods are the same for the treatment.
If you cannot grow the pest in question and there's a lot of variation, between test, treatments, then it's going to be very hard to say much.
You need a good culture to test any algae from.
Regards,
Tom Barr
