High Levels of TOC in the Reef

[Hans-Werner]

I have seen maybe 100 N-DOC tests and no one have had a value of over 8.5 ppm TOC in spite of how nutrient rich the aquarium have been and in spite of the use of DOC (alcohol). Among aquarium tested is my own (rather nutrient rich) and a system where PO4 is around 0.4, NO3 around 100 and temp around 12 degree C (low bacterial consumption of organic carbon). Here it was around 12 ppm.

I see some conclusion which are not correct in my eyes.
Use (dosing) of ethanol - may in fact lower the concentration of TOC because co-degradation/co-metabolization of persistent OC and labile OC may occur and likely occurs in reef tanks. This can in fact mean lower TOC than in tanks without dosing of labile OC like ethanol, scientific results say.

Nitrate means you have working bacterial degradation (better wording? breakdown?) and whole chains of bacterial degradation. This may not work well if some micronutrients are in short supply. Besides this nitrate is a strong oxidant which itself may support breakdown of TOC. Also sufficient macronutrients like nitrate and phosphate may increase degradation of TOC.

If the bakterial degradation would really be very low, you would hardly have nitrate in your tank. Please remember, one of the strange things in Daniels tank is that also the "N/NO3 calculated" ratio is marked red. This points to severely disturbed bacterial degradation in my eyes.

I still believe that the nature of the TOC in this case is the main key - fast followed by your suggestions.

Maybe, but it doesn't matter as long as phosphate is so low and nearly all essential trace elements including iodine are below the detection limits.

Also keep in mind, phosphate calculated from phosphorus from ICP-OES means there is not only no othophosphate but no phosphates at all, no organic, poly, whatsoever phosphates, which could have remained in these states due to lacking bacterial or enzymatic breakdown.

 

[Lasse]

This may not work well if some micronutrients are in short supply.

This is a thing that I have notice in the past according to nitrification. It seems like step two (NO2-> NO3) can be affected if there is no PO4 available (the "hung" of the nitrification process in the start of a new aquarium is one example) I have not seen this according to the first step NH4->NO2

I have seen maybe 100 N-DOC tests and no one have had a value of over 8.5 ppm TOC in spite of how nutrient rich the aquarium have been and in spite of the use of DOC (alcohol). Among aquarium tested is my own (rather nutrient rich) and a system where PO4 is around 0.4, NO3 around 100 and temp around 12 degree C (low bacterial consumption of organic carbon). Here it was around 12 ppm.

I have change this because it could be misunderstood

I have seen maybe 100 N-DOC tests and no one have had a value of over 8.5 ppm TOC in spite of how nutrient rich the aquarium have been and in spite of the use of DOC (alcohol). Among aquarium tested is my own (rather nutrient rich) and a system where PO4 is around 0.4, NO3 around 100 and temp around 12 degree C (low bacterial consumption of organic carbon). In OP:s tank TOC was above 12 ppm

Sincerely Lasse

 

[Hans-Werner]

This is a thing that I have notice in the past according to nitrification. It seems like step two (NO2-> NO3) can be affected if there is no PO4 available (the "hung" of the nitrification process in the start of a new aquarium is one example) I have not seen this according to the first step NH4->NO2

Very interesting detail, Lasse. The first step may and usually will be processed by archaea and not by bacteria, especially at low ammonium concentrations.

As far as I know the second step has to be processed by bacteria, at least I do not know about nitrite oxidizing archaea, only about ammonia oxidizing archaea.

But there may be another reason, the similarity between the nitrite and the chloride ion that causes the freshwater fish to take up nitrite instead of chloride.

 

[Dan_P]

Honestly, this seems to just keep spinning around in a circle. So many theories and generally the same suggestion. If this is some strange contaminant (PFAS/Petroleum/Dissolved Carbon...) most of this stuff is typically removed with GAC or Resin. Therefore just get the media reactor full of carbon change it out every few days for a 2-4 weeks and retest TOC, it will drop. Then go back to your normal operation and retest it after a few months to see if it increases again. If this is proven then you have confirmed some source TOC is present in your operation. There is no need to to spend $300 on a PFAS test.

If adding nutrients depletes immediately because of the high TOC then it is biodegradable carbon and would consequently reduce TOC. You just need to take the steps to drop TOC.

Maybe I missed it but are you said you switched water sources to something other refers are using but do you have using RODI? Is the TDS always zero? Do you store your water in an HDPE container?

I too feel like we are all over the place, but the early days of undisciplined problem solving happens this way. And it works sometimes. I took some time yesterday to reread this entire thread. Here are some thoughts and (sorry) further requests for information

“High TOC Kills Coral hypothesis”
I don’t think we did enough work to challenge this hypothesis. My reading over the years taught me high DOC encourages bacterial growth that is detrimental to coral, not the DOC itself. What do we think?

“Toxic Organic Compound(s) Present”
If there is a toxin present, would it only affect the coral and not other invertebrates? Is there an example of such a toxin? Thought on this specificity?

Further Requests
1-We need to see pictures of the tank and sump. What is algae growth like? Any cyanobacteria mats? The tank nutrients are so low that any R2R member seeing this would be shouting “look out, you are playing with fire! Dinoflagellates bloom is inevitable!!!”

2-We need to see all NDOC results and dates the samples were taken. We need to discuss possible trends. Especially interesting to us would be the NDOC results after the water change experiment and after ozone treatment experiment.

3-How much and what type of food is added per day? Other nutrient additives? We need weights so we can understand the nitrogen and phosphorous import.

4-How much air does the skimmer draw every hour?
Even though air quality seems good with low TVOC, when drawing a lot of air through the skimmer, the cumulative exposure of the water to these impurities can be pretty large.

 

[KimG]

Hi Daniel
Any changes in your tank status? Any improvement?
Cheers