Does high nutrients in water column = lower microbial diversity?

[snowballs99]

I saw surdipta's AGA talk and noticed how his algae infested tanks had the lowest microbial diversity. He also said how surface film was basically the fastest sign that something was going wrong in the tank and maintenance should be done.

I seem to agree with this as well. Whenever I dose EI tanks usually only go for 2-3 days before I get surface film. If there is surface film, you are 1 week away from an algae outbreak.

I have never had a single tank where I dose any singificant nutrients that didn't get a surface film. The only tanks that never got it, was the ones that was extremely nutrient poor. Like a bucket of water left outside for a month. Eventually that water becomes crystal clear as all the nutrients are exhausted.

 

[ElleDee]

I would resist the urge to take his (interesting and informative) observations and turn them into some over arching principle. First, he didn't look at the nutrient content of his water column at any point, so who knows what they were. He doses more on the leaner side, so it was probably very different than tanks that are EI dosed, but again, we don't have any data on that either way.

Second, we need to look at the bacterial composition of a lot more tanks before we can start to give weight to any correlations we might find. He looked at just a couple of tanks, and only one that was out of balance. It would certainly make sense that out of balance tanks would have more pathogenic bacteria and less diversity, but we need to verify that. Maybe that's only the case in some cases and not in others. We don't know.

 

[Naturescapes_Rocco]

I would resist the urge to take his (interesting and informative) observations and turn them into some over arching principle. First, he didn't look at the nutrient content of his water column at any point, so who knows what they were. He doses more on the leaner side, so it was probably very different than tanks that are EI dosed, but again, we don't have any data on that either way.

Second, we need to look at the bacterial composition of a lot more tanks before we can start to give weight to any correlations we might find. He looked at just a couple of tanks, and only one that was out of balance. It would certainly make sense that out of balance tanks would have more pathogenic bacteria and less diversity, but we need to verify that. Maybe that's only the case in some cases and not in others. We don't know.

This is a great answer, better than anything I could have thought to say.

I've run tanks absolutely dense with nutrients (30-9-40 or more in macros alone) without algae. Nutrients don't cause algae on their own, neither directly nor indirectly. We've proven that so many damn times over. Algae and bacteria and these systems are almost unfathomably complex. WHY algae occurs is not because of one thing, but a multitude of things, always.

I'd love for more science and testing to come out in regards to microbial diversity in our tanks. How DOES one introduce diversity beyond adding organic compounds?

 

[ElleDee]

I'd love for more science and testing to come out in regards to microbial diversity in our tanks. How DOES one introduce diversity beyond adding organic compounds?

I am pulling from memory here but the impression I got from the talk was that the microbial diversity was likely the result of a healthy tank rather than the cause. IIRC the algae tank was fixed with some maintenance, not by doing anything with the microbiome directly.

It's funny that the issue of surface scum from this talk came up. My big tank is having some issues with detritus on the leaves despite my maintenance efforts (my fish finally figured out how to hunt shrimp, then I had a bga outbreak and then it died leaving a brown film everywhere with no shrimp to clean it up, it's a whole thing) and surface scum has been an issue and I just got a skimmer yesterday. I am not sure that addressing the scum directly is going to help as I also see a clean surface as a downstream effect from a balanced tank rather than a direct contributor to it, but better gas exchange can't hurt. I'm hoping that improved oxygen in the tank will speed detritus breakdown and eventually I'll clear it, but we'll see.

 

[Burr740]

I dose in the neighborhood of ei level ferts in 14 tanks and the only time there's ever a surface film is if a tank is immature, or the bio population gets disrupted

Raising ferts should not cause a surface film. I can see how going from zero in the water to a lot might, but it should go away on its own in a week or two when the bio population adjusts