isnt a fish tank LOADED with pro-biotics? We talk about "Benifical bacteria" why should we need to mix bactillus in food,
Hello; I do not have extensive experience with these "probiotics" in an aquarium but let me chime in anyway.
My take is that yes there are the "beneficial" bacteria strains we hope to cultivate for dealing with ammonia and nitrites. There are many other bacteria strains in an aquarium, some good to have, others cause problems such as cyanobacter. I figure there are many others somewhere in the middle neither hurting nor helping much.
All tanks with living things will generate organic waste materials. Excess food bits, fish poo which may retain some organic material due to less than 100% digestive efficiency in animals. Plant parts in a planted tank. Algae that may be scrapped off glass which winds up trapped in a filter.
These bits of organic "detritus" wind up in the filter or in the substrate and other nooks. Nature will provide decay organisms including bacteria and the stuff will rot wherever it happens to be. We might get lucky and have the ideal types of decay organisms drift into out tanks. May be that most of us do not get that ideal group of better decay types.
A septic tank has much the same situation as the rotting organics in a tank. When I talk to folks about the RID_X I put into my septic tank, some retort "just take a dump and the bacteria will be added that way."
My take is the folks at RID_X and the other such places have put together a mix of bacteria and "enzymes" more closely tailored to the job of reducing organics in waste. For me that means I have to have my septic pumped out much less often as the residual solids are fewer. I think the principal is much the same in an aquarium.