I am hesitating all(almost) these kind of products because of several considerations:
1)I do not believe that lack of a certain bacteria/bacterial function mostly depends on lack of that cell-population, but more lack of environmental factor such not enough carbon source and/or not enough with anaerobic zones (if we are talking about denitrification).
2) Aerobic heterotrophic bacteria you have automatically(and also anaerobic sorts for sure), so I do not believe that the carbon source-method is depending on adding bacterial culture at all. They are already there.
I think that the best way to regulate a certain bacterial growth is to establish the correct environmental factors. So for instance if you have high nitrate you probably have not enough with anaerobic zones (very common today with too thin sandbeds in the display-tank), and the action is to establish anaerobic zones, by more sand (or even better a DSB) or an external nitrate reactor (very easy and well-working device at least according to my experience). If we talk about nitrification is it probably never a deficiency of that, no none experience high nitrite besides the first weeks..or?.. And if we wants to promote bacterial growth of aerobic heterotrophic sort(a majority of bacteria is of this sort), we only have to supply with carbon, not the bacterial itself. And concerning carbon there is no rocket science or anything mysterious behind the different brands. Carbon source is extremely cheap where ordinary ethanol, methanol, acetate, works perfect.
And, I also do not believe in monoculture-developing. Thats it is very hard to achieve, in a environmental that consists of extremely lot of organic compounds and microorganisms. And IF you achieve that, it is mostly not possible to cure that with adding good bacteria. In my occupation (I work as surgeon) I can tell, that if you have a pathogenic bacteria it is not working at all adding some good bacteria. The concurence-theory with PRObacteria (adding good bacteria) is mostly not working against patogenic bacterie. The same reason it do not believe it works adding probiotic bacteria to concur cyanobacteria. We have all tried these and it does not work i should say.
Concerning the other addings such minor elements, we know very little about the positive effects. I think that it is quite common with overdosage concerning minor-trace-elements and also concerning some macro elements such Potasium, as all these consumes very very little, some of them hardly no consumption at all. Potasium for instance if you not uses zeolit, has a very low rate of consuming, and same for strontium. I think Iodid, is maybe the only elements that really depletes and also that replenish of this have proven benefits. I have a big SPS tank, and never replenish nothing more than Iodide, (besides that the Ca-reactor gives), and measures with Triton lab ICP-OES once a month almost, and never have had a lack of a minor elements (except when I tried the Brightwell salt, where bromide is very low).
Maybe we shall lay more money in ICP-OES-testing and more single dosing according to that results (which I guess would lead to a drastic minimizing of selling trace-elements...) to avoid overdose? That is my believe as we have the new technique today
Sorry for extensive "answer"...this is so interesting my friends:_)
Jonas Roman