[Cavan Allen]

I suspect that as opposed to fish only tanks, where autotrophic bacteria (amonnia reducers) should be favored, in planted aquariums it's actually better to favor heterotrophic bacteria (organics, sludge reducers). As we know, plants prefer ammonnia as a food source, so I don't think we really need bacteria to reduce that to nitrate. But we do need bacteria to reduce organics. If that's the case, I suppose the "you don't really need a filter" and "more filtration!" crowds are both right to a point. I may be wrong, in which case I will return to plant identification.

 

[Yo-han]

That is my point of view too So for my new tank I'm working on how to optimize the heterotrophic bacteria growth and minimalize ammonia reduction and nitrate loss

 

[krisw]

That is my point of view too So for my new tank I'm working on how to optimize the heterotrophic bacteria growth and minimalize ammonia reduction and nitrate loss

Deep substrate beds?

 

[SBS]

Well most heterotrophs are facultative anaerobes, so it depends on the conditions in the tank what exactly function they perform. Depending on the conditions, they can decompose organics in the presence of organics and oxygen, or convert nitrate to nitrite in anaerobic substrate(which is scary), to converting ammonia to nitrite when in the water column and in contact with ammonia and oxygen( bacterial blooms are caused by fast expanding heterotrophic bacteria) They can double up their amount in a couple of hours where autotrophs such as nitrifying bacteria takes 24hrs and more. So they have the potential to take up all surfaces if let free and you end up with nowhere for the nitrifying bacteria to grow. Which eventually leads to water quality issues because heterotrophs are one million times less efficient in converting ammonia to nitrite and they can't really convert nitrite to nitrate but can convert nitrate to nitrite in anaerobic conditions.

So personally, although they are fine in small numbers in the substrate when they decompose organics in the substrate, they are not welcomed either in an anaerobic substrate or in oxygenated water column.

Anyway, with all that said we are already promoting good heterotrophic activity by ensuring they have organics and oxygen inside the substrate. Planting with heavy rooters, having not so deep substrate, a bit of flow reaching it too, detritus from fish and fish food should ensure they have all that they need to be sludge reducers and not something else.
If they don't have oxygen, they won't decompose organics but do something else harmful that happens in anaerobic conditions. If they don't have organics as their nitrogen source they'll be converting ammonia instead if oxygen is present.

 

[JeffyFunk]

Update: I finally got motivated and fixed the TOC analyzer (long story short, there was no motivation on my behalf to get it fixed (since we REALLY don't use it much at work anymore) and a complicated set of problems to be fixed...). Here are the results from the samples analyzed.

But before that, a few caveats... (1) the metals analysis is still valid. The metals have a holding time of 6 months (except Hg) when preserved with HNO3 so those are still good. (2) the TOC samples were preserved with HCl when i got them, so technically, they should be still good. That said, they are over the recommended holding time of 30 days, so there's no way to really know. In order to see how well the preserved samples hold up over time, i am going to analyze them all again in a few months time and then we can compare the results.

Looking at the aquarium results and comparing them with the TOC analysis results at work, the one thing that can give us some insight of the quality of the results was the matrix spike & matrix spike duplicate QA/QC results. A matrix spike/matrix spike duplicate (MS/MSD) is when you add a known quantity of the analyte (10 ppm TOC in this case) to a sample and then calculate the % recovery of the matrix spikes versus the original sample and to each other (acceptable results are +25% of the theoretical value).

For the samples that were prepared and analyzed right away (i.e. prior to the TOC machine breaking), the MS/MSD % recoveries are typically been between 90-105% recovery. For the samples that were prepared and analyzed much later (i.e. after the TOC machine broke), the MS/MSD % recoveries were more erratic - from 37%-127% recovery (64%-114% if we exclude the highest and lowest % recoveries). Of the 10 MS/MSD solutions prepared, only 3 were outside the acceptable % recovery range of 75-125% and the average % recovery was actually 90%.

The take away message of this all? The results should be interpreted with a grain of salt but are probably fairly accurate (though of course we have no way to find out).

| New Samples            | Al  | B   | Cu  | Fe  | Mn  | Mo  | Zn  | 

| CA Tank 10/18/13       | 0.02| 0.12|  <  | 0.30|  <  |  <  | 0.09|
| CA Tank 10/23/13       |  <  | 0.13|  <  | 0.03|  <  |  <  | 0.09|
| CA Tank 10/23/13       |  <  | 0.12|  <  | 0.14|  <  |  <  | 0.08|
| CA Tank 10/30/13       |  <  | 0.13|  <  | 0.20|  <  |  <  | 0.27|
| CA Tank 10/30/13       |  <  | 0.10|  <  | 0.02|  <  |  <  | 0.03|
| CA Tank 11/13/13       |  <  | 0.13|  <  | 0.05|  <  |  <  | 0.03|
| CA Tank 11/22/13       |  <  | 0.12|  <  | 0.13|  <  |  <  | 0.03|
| CA Tank 12/12/13       |  <  | 0.12|  <  | 0.01|  <  |  <  | 0.05|
| UDGags Tap 1/13/14     |  <  |  <  | 0.04|  <  |  <  |  <  | 0.01|
| UDGags Tank 1/13/14    | 0.05|  1.5| 0.18|  11 | 0.03| 0.09| 0.57| 


| New Samples            | TOC | K   | Ca  | Mg  |Gen. Hard.| Comments  | 
 
| CA Tank 10/18/13       | 11.0|  28 |  16 |  4.5|  8.6 dGH |           |
| CA Tank 10/23/13       | 13.1|  36 |  24 |  5.8|  4.7 dGH | Before WC |
| CA Tank 10/23/13       | 12.1|  28 |  16 |  4.6|  3.2 dGH | After WC  |
| CA Tank 10/30/13       | 13.0|  34 |  22 |  5.3|  4.3 dGH | Before WC |
| CA Tank 10/30/13       |  9.9|  26 |  15 |  4.1|  3.1 dGH | After WC  |
| CA Tank 11/13/13       | 10.4|  31 |  18 |  4.6|  3.6 dGH | Before WC |
| CA Tank 11/22/13       |  8.0|  32 |  18 |  4.2|  3.5 dGH | Before WC |
| CA Tank 12/12/13       |  8.9|  33 |  20 |  4.2|  3.8 dGH | Before WC |
| UDGags Tap 1/13/14     |  1.2|  2.8|  18 |  29 |  8.8 dGH |           |
| UDGags Tank 1/13/14    | 22.4|  78 |  20 |  26 |  9.2 dGH | Before WC |

p.s. i haven't been following this conversation in quite a while since i've just been focused on other things (@ work and @ home - it's gardening season!). i have some thoughts and comments on things, but will post those things later since i just wanted to get this information out first.

p.p.s. another thing that i noticed. when i prepared the samples for analysis, i forgot to preserve a sample for duplicate analysis (as part of our standard QA/QC protocol). So i just poured a duplicate of UDGags Tank 1/13/14 into a vial (which was UNPRESERVED) and analyzed that as the duplicate. The sample value (preserved) was 22.4 ppm TOC. The duplicate value (unpreserved) was 2.2 ppm TOC. This just shows that the acid preservative was doing something... we just don't know how well it worked...

 

[Tugg]

JeffyFunk, if the analyser is back online, does this mean you would like to start collecting samples again?

 

[JeffyFunk]

JeffyFunk, if the analyser is back online, does this mean you would like to start collecting samples again?

I've always been able to analyze samples for metals analysis.

But, yes - The TOC analyzer is working again so i will be happy to analyze samples for people if they want to collect them.

 

[Cavan Allen]

Compared that to my records and it looks like the Organit caused roughly a 25% drop in TOC. That was 13 tablespoons in an Eheim filtering my 40.

Will send more samples. My tank is nearly spotless now, with growth that's for the most part quite good.

 

[Yorkie]

Hi Everyone,

This has got to be one of the most interesting and most useful threads I've ever read on any Aquarist forum! I'm so pleased to have discovered this thread and, indeed, APC. The thread has confirmed for me the importance of DOC/DOM. And I note that the thread was started back in 2013!

Yorkie =D>=D>=D>=D>

 

[Yorkie]

Hi Everyone,

This has got to be one of the most interesting and most useful threads I've ever read on any Aquarist forum! I'm so pleased to have discovered this thread and, indeed, APC. The thread has confirmed for me the importance of DOC/DOM. And I note that the thread was started back in 2013!

Yorkie =D>=D>=D>=D>

Hi Again,

I see that I wrote the above just over a year ago.

I have a non-logging ORP electrode and meter on which I keep a close watch of ORP. This reading is typically 350 to 400 mV. If it varies outside this range, it's a rare occurrence and is a cue to investigate the cause.

Yorkie

 

[Yorkie]

Today, 2014, we, here on APC are talking about things that should have been in the spotlight a long, long time ago. Instead we have all the things you see me bash left and right.

Hi @niko and all other contributors to this amazing thread,

And, now that a further eight years have passed, it would be very interesting to hear your views on how much, if any, we have progressed in understanding the importance of organics in our tanks.

Yorkie