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Organics Analysis

108557 Views 450 Replies 29 Participants Last post by  Yorkie, 
J
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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R
I watch the cycling of the powerhead at 8am and its affects on the orp. Just before the powerhead shut down the orp was 202 and after it shut down, the orp went up to 215 and settled in at 213. So to answer your question Niko, it appears the real orp at 8 AM should be 11 mv higher.
And to add more to the confusion, I removed the powerheads electrical plug and place in in another power supply close by. The result this time is the orp went from 213 to 233 mv.

So I do not intend to let the confusion of orp get the best of me because "Randy Holmes Farley" a well respected chemist who keeps reef aquaria does not use one. He says there are too many complexities that are involved that will change the values. There are many things about orp that even the best minds of science do not understand. So what I intend to do is to use orp only occasionally when I decide if to use an oxidizer to tell me when enough is enough. A value of 300 to 350 might be the correct value, but I need to do some more research on it.
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Zapins
If there is electrical interference then removing a specific amount of water from the tank in a plastic container should help eliminate the interference you mentioned. Test the sample water in the container not the tank water.
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R
The ro water in a glass read 267 mv while sitting in the water.
It read 256 mv when lightly stirred. both readings were taken at 64 degrees F.

The tank water read 197 mv. But when a sample was placed in a plastic container, it dropped to 190 mv and slowly climbed back to 197 mv. So I am ok there. ph at time of readings was 6.47 to 6.50.

Now I have to wait till 8 pm when the powerhead kicks on and see if the interference is temporary or continuous.
On another point, I checked out a new orp probe and it has the same characteristics as mentioned before; so my probe is ok after all. It will be placed in storage solution until I need it to check the oxidative power as I add some to treat the tank either for organics or bsa and/or bba.
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N
"Randy Holmes Farley", a "well respected chemist"... and an internet aquarium guru. I can easily think of another example. Don't let me say anything negative, I'll just scoff instead.

Whatever recommendation someone is giving are all fluff because if it was so clear and working so well aquarium problems would be unheard of by now. They are not. Nothing else to say. But the information about ORP is interesting by itself.
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T
I don't think we are even close to understanding how orp works but as you said it is very interesting

Sent from my SGH-T599N using Tapatalk
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R
From what I read on the net; one of the authors stated that orp was being misinterpreted and the manufacturers were quick to pick up on this. Someone stated that it measures water quality. So lets separate fact from fiction.
Orp meters measure the oxidative or reductive power of the solution which may or may not improve water quality but it does not measure water quality. For instance; if one takes a glass of ro water that has germs in it and adds a few drops of chlorine, it will kill the germs but is it drinkable? So what was improved? Yes, the germs were killed but what is gained if we cannot drink it? So that's what orp is all about. Too much oxidation is harmful and too much reduction and the water would be tasteless.
Its a balancing act between both.
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Marcel G
According to my opinion the redox is our best bet in determining the water quality. I know that it could be tricky, but if you use the values reasonably, then it can give you some hints on what's going on in your tank (what are the tendencies/trends). If you have 300-400 mV ORP then I would say that you probably have very good conditions in your tank. And on the contrary, if you have 100-200 mV, then you have probably some serious problems.
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Phil Edwards
ORP in itself isn't terribly complicated; it's massive jumble of redox reactions that go on in water that are. ;) As a measure of water quality, it's pretty good too. We're not talking about potability, but overall pollutant load. Water can be high quality from an environmental standpoint even if it's not potable.

Thanks for the observations rjordan, they're interesting. I'm glad to hear your probe is working as intended. You were getting 267 mV? That sounds kind of low. What does it get to after you've done a water change and cleaned your filter?

PaulG over at APE shared some really telling pictures of graphs on his Apex logger. ORP and DO had a fairly close relationship with ORP lagging an hour or so behind DO. DO had a min/max of 40%/90% saturation, with 8.3 ppm being 100% and ORP ranged from 300-350 mV with small drops after feeding and/or supplementation with chelated ions.

Check out this thread and take a look at his graphs. They're telling. http://www.aquaticplantenthusiasts....iscussion/5612-ph-orp-planted-aquarium-2.html

I really want to get an Apex now. LOL
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N
Man! How did you make it without an apex so far???


I guess my dear granny was right again. "You can when you want!" she always told me....

:D
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N
So how is it that ORP measures all kinds of oxidation/reduction but when PaulG pumped raised the dissolved oxygen the ORP did not jump up immediately?

I was under the impression that Oxygen itself would raise the ORP just like that! Add an oxidant = raise ORP. But it sounds that ORP measures something else. Can someone clarify?
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J
rjordan393 - Question for you... How did you calibrate the ORP electrode? What reference solution did you use? According to Standard Methods, we verified the response of the electrode using ZoBell's solution (Light's solution is the other reference solution). The ZoBell's solution is orange in color (from the Fe+3/Fe+2 species).
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Phil Edwards
Niko,

ORP is a measure of *potential* and must take into account the demands the system is placing on oxygen. Even though DO may increase it takes time for the dissolved O2 to get to a point where dissolution rates are greater than biological or chemical demands. Redox chemistry can get really complex and that complexity is what's governing ORP. That's my guess as to why there's a lag, at least. I'll need to take some more time to think about it.
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D
niko said:
So how is it that ORP measures all kinds of oxidation/reduction but when PaulG pumped raised the dissolved oxygen the ORP did not jump up immediately? I was under the impression that Oxygen itself would raise the ORP just like that! Add an oxidant = raise ORP. But it sounds that ORP measures something else. Can someone clarify?
Click to expand...
A layman's thought on it. Plain old O2 isn't a very reactive oxidant. You can breathe 100% pure O2, your lungs won't immediately start burning away. Breathe pure O3 or H2O2, that's another matter. ;) So adding oxygen in the form of O2 might not raise ORP directly, unless/until other processes transform some of it into more reactive versions.
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R
I believe when the tank inhabitants are fed that this will cause a delay in the oxygen level. So far I found out that ferris gluconate will drive down orp. Did Paul G. also monitor pH. ? Normally If the pH goes up, then the orp drops. I say normally as there are things that can interfere. Unless what I been reading on the net is completely wrong.
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R
Jeff,
I used American Marine ( the mfg. of the Pinpoint line of products) 400 mv calibration solution for orp. They do not supply a reference.
However, I found out that my meter needed calibration. It was last calibrated on 2/22/14. That is too soon to need calibration again. I think I know how it went out of calibration. I tested my tap water and the value went to 550 mv and the meter seems to need calibration when it is use for sudden and higher orp values. this is not in the instructions.
So my data on orp should be about 70 to 80 mv higher then reported. What a bummer!
The meter is now calibrated and my present orp is 284 mv. It was at 294 before I fed the fish.
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Phil Edwards
rjordan,

Yeah, Paul also had pH. The Apex keeps it at 6.7 +/- 0.02, so it's rock steady for all intents and purposes. The Nernst equation does predict lower ORP at higher pH, but that's typically only useful for certain things like lab work or industrial chemistry where reactions are controlled and there's no biological intermediate. (Jeff would be the best one to talk about this in-depth).

It's common for salt water tanks with a pH around 8 to have ORP values of 350-400 mV. It makes sense that ORP might be higher under ideal/theoretical conditions when pH is lower because there are more H+ floating around waiting to accept an electron and be reduced, or be the oxidizing agent for an electron donor. We see lower ORP (via lower eH) in aquatic soils with fairly low pH. Typically, as O2 and carbon are consumed and the redox potential/ORP goes down, then acids form and pH decreases.

Ferrous gluconate will drop ORP thanks to the gluconate (organic molecule) chelator. Feeding causes a temporary drop in ORP too. Anything that can take an electron from something else (be reduced) that's put into the tank will affect ORP as some of the reactive species the probe is measuring are now being used for redox reactions rather than just sitting around waiting for something to play with. We've also got to consider the impact of metabolism on ORP too. The higher the O2 concentrations the greater the potential for microbes, higher animals, and plants to sustain aerobic metabolism and consume (reduce) organic matter. COD and BOD both have an impact on ORP.
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D
Perhaps this is slightly off-topic, but discussion of ORP has me wondering about something regarding use of H2O2 as a whole-tank algae treatment.

As a result of my "One-Two Punch" treatment, I've gotten countless reports that suggest the effects of H2O2 are highly variable. For example, in my tanks 4tbsp/10G will have good algicidal effect, and appears harmless to fauna. But in most other folks' tanks, that's too much and will kill fauna; instead for them, 2tbsp/10G has the same effect that the higher dose has for me.

I've long believed DOC has at least something to do with this, as it provides something that will rapidly react with H2O2, and decrease the amount available to react with other things. The oxidative power of H2O2 also increases with decreasing pH. But I get the feeling that neither of these adequately explains such a widely variable effect.

Although thanks to this thread I have a better understanding of ORP, I'm not confident enough in its implications to answer the following question: Is it possible that ORP could be the prime variable here?
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R
As a result of my "One-Two Punch" treatment, I've gotten countless reports that suggest the effects of H2O2 are highly variable. For example, in my tanks 4tbsp/10G will have good algicidal effect, and appears harmless to fauna. But in most other folks' tanks, that's too much and will kill fauna; instead for them, 2tbsp/10G has the same effect that the higher dose has for me.
Click to expand...
From the reports that I have read state that 15 ppm of 3% h2o2 per 48 hours is considered by many to be a safe dose. Your dose (4 TBS per 10 gallon) which is equal 60 ml is way over the recommendation.
H2O2 can affect your nitrifying bacteria, fish and inverts if over dosed. Take a look at this article from the Aquarium Wiki where the author gives the safe dosage.
http://www.theaquariumwiki.com/hydrogen_peroxide

I decided to use H2O2 as a spot treatment only. However, I do use much more in my preparation water two weeks before it goes in my aquarium in the hopes it will remove DOC from my treatment water.
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D
rjordan393 said:
From the reports that I have read state that 15 ppm of 3% h2o2 per 48 hours is considered by many to be a safe dose. Your dose (4 TBS per 10 gallon) which is equal 60 ml is way over the recommendation.
H2O2 can affect your nitrifying bacteria, fish and inverts if over dosed. Take a look at this article from the Aquarium Wiki where the author gives the safe dosage.
Click to expand...
I'm quite aware of various recommended dosages, and the effects. The whole point of my post is that generalized recommendations aren't particularly useful, because the dosage vs. effect varies from tank to tank. For example, I have five tanks in which the recommendation you provided has no effect whatsoever, on anything at all. 4tbsp/10G was determined experimentally, by starting low and increasing it 0.5tbsp/10G at a time until desired effects were seen, without side effects. And so that is the proper dose for these tanks, regardless of any recommendation.

I simply want to solicit additional ideas on why it behaves this way.
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R
There was this one time that I did not follow the recommendation and the result was my nitrites climbed to 0.4 ppm. But I also intervened by making additional water changes and adding Seachems Stability before it got any higher. I was adding H2O2 every night and the recommendation was every 48 hours per dose. So maybe the answer your looking for lies in how often you dose and how much.
Another thing one needs to be concerned about is the orp of the dose. How high is too high?
If your 5 tanks are on the low side, say about -200 mv, then there's a reason why you can dose higher. One aquarium business owner recommends + 350 mv as a temporary orp to clean up organics.
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