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Organics Analysis

108563 Views 450 Replies 29 Participants Last post by  Yorkie
The purpose of this thread is to (1) try to gather samples and data on the amount of organic pollution (i.e. Demand) that people have in their aquarium and (2) see if there is a correlation between the amount of organics measured (as TOC) and algae growth, specifically BBA.

The topic of 'organics' in the aquarium as a pollutant has always been very vague ... Often times, people talk about 'organics' as a problem in the aquarium but if you ask them about specific values of organics that cause problems or are acceptable or ask for specific articles about organic pollution level studies, most people are not able to provide any values or specifics. Instead they just wave their hands in the air and mumble generalizations like 'organics are bad and need to be as low as possible'.... how low is good? how high is bad? What are the average concentration values? Is there actually a correlation at all? That is the goal of this thread - to try to put generate analytical data on organic pollution (as TOC) and see if there is indeed a correlation between TOC concentrations and algae.

According to the Standard Methods Handbook, there are many ways to measure 'aggregated organic constituents' or 'organic pollution'. COD (Chemical Oxygen Demand) is the most common method of measurement and is defined as the amount of a specified oxidant that reacts with the sample under controlled conditions. Other methods of organic pollution analysis include BOD (Biologcial oxygen demand), TOC (total organic carbon) and TOD (total oxygen demand).

I would like to gather and analyse samples for organic analysis for their TOC content in order to see if there is indeed a correlation between the TOC of a particular aquarium and the presence of algae, specifically BBA. I work for an environmental laboratory, one of the instruments we have is a TOC analyzer (total organic carbon). This is a machine that measures the carbon containing compounds in your water by converting the carbon to CO2 and measuring the CO2 via an IR detector. Basically, there are two steps. In the first step, the sample is acidified. This converts all the inorganic carbon (HCO3- and CO3--) to CO2 and the amount of CO2 is determined. This portion is the TIC (total inorganic carbon). In the second step, an oxidant is added to the sample to decompose all of the organic carbon to CO2 and, again, the CO2 is detected. This portion is the TOC (total organic carbon).

If you are interested in participating and sending me samples for analysis, I ask that you collect and label your samples with the following information:

Name, Date of Collection, Aquarium Name (if you have multiple aquariums, usually the size), BBA present or not, CO2 injection or not, Water change frequency (and when your sample was collected with regards to them)

Also, be sure to include a sample of your source water (tap, RO water, RO water reconstituted).

For convenience sake, please collect samples in a DOUBLE SEALED ziplock sandwich sized bag, ~1/4 to ~1/2 full. Remove as much air as possible from the bags and seal the opening with packaging tape (or any other heavy duty tape like duct (or duck) tape, not scotch tape). Place all of the water samples into a larger gallon size ziplock bag for extra protection in case the bags leak. If you need or want to collect multiple samples over time, please refrigerate all samples for storage in order to minimize the amount of TOC degredation. Please PM me for shipping information.

I will analyze the samples and organize the results into a table format so we can then all analyze the data. If you would like your data to be presented as anonymous, please just include a note with your samples and i will report them on this forum as anonymous (but i need to know the actual name in order make sure i receive your samples and for proper sample tracking.)

Disclaimer. This analysis is for personal use only and all results may not be used for compliance testing and monitoring or legal use. I will not be held responsible for sample shipping, sample contamination and any loses that may occur.
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Regarding organics in El Natural. After a couple years of being established without cleaning or maintenance your substrate cap will gradually accumulate a mulm cap. Still no algae problems.

My old ecology prof actually grew plants in inert gravel saturated with mulm collected from other tanks and accumulated.

Maybe the cap locking in the organics has something to do with it initially in the tank's younger stages... But I don't think that's all there is to it.
No, I wouldn't imagine fully decomposed mulm product releasing organics. But the process of allowing it to accumulate (in other words, letting a layer of organics sit in the tank long enough to fully decompose on a regular basis without removal) would. I guess the real question is how much of it is actually accumulating, since we typically don't do water changes.
Ok, so... Let's assume organics are the culprit... What have we learned? What do we change?

Don't overfeed? Keep a sensible bioload? Don't grow your plants at pointlessly fast rates just because you can? Facilitate fast and healthy decomposition? Use a good substrate to bind compounds from the water?
So it's organics, but it seems to matter where they are exactly, in the water column, covering surfaces of the tank or in the soil/filters decomposing happily away from light availability for algae to take hold.
Makes sense to me.

So how do you figure this differs for Walstad tanks then, which are able to be stable in stagnant water, or just enough minimal flow to circulate nutrients?

I guess what I'm asking is, why do Walstad tanks get away with using substrate decomposition only, but the rest of the hobby seems to feel that decomposition MUST take place only(or mainly) in the filter?

For someone who's done a lot more stagnant tanks than filtered tanks, it sometimes looks like people are forgetting what substrate decomposition can do for a substrate, and the many ecological roles it plays which support the plants and drive ecosystems (it seems we have a lot of mulm fans here already), and are instead trying everything they can to pull all the waste off the bottom of their tank to trap it in their filter (Why? So it can be removed easily to prevent decomposition?). Then they wonder why there's bits of waste floating around in their tank that never seem to decompose properly...

From my perspective it seems a bit counter-intuitive... Inhibiting a natural plant-supporting process by separating it far away from the plants with the notion of strengthening a miniature ecosystem that's intended to support plants.
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I don't think high tech keepers promote any decomposition whatsoever. Organics is considered the devil and gets "cleaned" from every surface or device as much as technically possible. This is supposedly to prevent decomposition bacteria to settle in as it competes with the nitrification bacteria for oxygen. That's one of the ideas anyway, along with organics considered a trigger for algae in all type of tanks in most views.
Well said.

Rid our tanks of ecologically essential processes, control every parameter, make our system unflexible and sterile. That's how to achieve the stability and beauty of nature!

Lots of literature out there cites resource competition in nutrient-limited habitats and allelopathy as the mechanisms that plant communities use to force algae out of their habitats in nature.

It was over 30 years ago (at least that's the oldest journal article I have that explicitly mentions the transition) that aquatic plant cultivators began adopting the practice of using natural substrates to replace water fertilzation because they realized they could largely eliminate algal blooms and increase the stability in their cultures. So... Why exactly did the hobby revert back to a dependence on water column ferts?

This approach obviously won't do well in a bare bottom tank or tank with unbalanced inert substrate so it all depends on the setup what works best. For some tanks heavy maintenance is essential, for others the opposite could be essential.
Also well said. To each their own. It all depends on what kind of tank you feel like running I guess. I'm also not implying that it's all as simple as switching to a soil substrate or anything. I'm just more doubtful of the sources and experiments that provided the data we use as foundations than anything else.

I'm also somewhat bothered by how readily we accept information from anyone who seems vaguely qualified. A lot of notions in this hobby just seem bizarre and misguided with terrible evidence/data backing it up. As far as I've been able to experiment on my own, some of them seem downright false.

It's nice to see fans of mulm and natural substrates though!
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