Manuel Arias
Member
I assume that if a "lack of traces" is contributing to BBA, that means that they are well below toxic levels. Otherwise they are overruled.
We cannot monitor all the trace elements using tests, so even if Copper and Iron are OK, it might be possible other trace elements in deficiency. But this is also interesting: Copper, in fact, is an inhibitor of algae growth. In most of swimming pools some amounts of CuS04 are provided to avoid the appearance of algae. It might be possible that Guest, by having high levels of Cu, impacted in this point.
This link is explicitly devoted for this type of treatment and it is a brilliant reading for algae fighting techniques:
https://www.ideals.illinois.edu/bitstream/handle/2142/48968/ISWSMP-111.pdf?sequence=2
And this link, for example, explains the impact of Copper in algae evolution in freshwater reservoirs:
http://link.springer.com/article/10.1007/BF01866913
However, there are reason for not to use Copper sulphate but Copper chelates instead:
http://www.aquaticbiologists.com/aquatic-chemicals/herbicides/copper-sulfate
So some careful thinking should be carried out about this.
I knew about that, but long time forgotten, so just when Guest mentioned it, the idea came back to my mind. So probably, behind the extra addition of micronutrients comes this side effect of adding Cu, which makes the life of algae more difficult.