Discussing nitrate reduction

[Mels_Reef]

I have the same experience with carbon dosing as you describe.
Carbon dosing feeds all bacteria, not just the 'good' ones. I believe it contributes to an unbalanced microbiome. Tried them all, vodka, vinegar, diy nopox, bacto balance, ab+.
Also stopped running a refugium as some believe the algea docs contribute to unbalancing as well.
Unfortunately, this is of little help in your search.
My regime is opposite currently, after reducing feeding, we dose ammonium bicarb to maintain 10 ppm nitrates or so.

Thanks for helping me prove I’m not crazy regarding NoPox lol.

When you say algae docs are you referring to Dissolved Organic Compounds? I read that article that came out in a magazine (sorry can’t remember which) about DOC’s on healthy reefs vs unhealthy, algae covered reefs. I never used to use activated carbon until I read that article. I now change out about 2 cups worth every 3-4 weeks.

 

[Aquariumaddictuk]

I’m sure everyone’s experience is different but to imply I am ignorant about the effects of NoPox dosing on my SPS system is being kinda rude. Look at Pistondogs post. He also has problems with it, and various other carbon sources as well

I've implied nothing of the sort, I merely stated I'm sceptical of nopox dosing causing such dramatic damage IF dosed correctly.
I've also tried to suggest alternative carbon dosing methods because you asked if all carbon dosing methods were toxic, which they most certainly are not IF used correctly.

 

[Pistondog]

Thanks for helping me prove I’m not crazy regarding NoPox lol.

When you say algae docs are you referring to Dissolved Organic Compounds? I read that article that came out in a magazine (sorry can’t remember which) about DOC’s on healthy reefs vs unhealthy, algae covered reefs. I never used to use activated carbon until I read that article. I now change out about 2 cups worth every 3-4 weeks.

Yes, dissolved organic compounds. Algae doc promotes 'bad' bacteria that interferes with coral biome.
Sorry can't find the video, Dr Forest Rohwer talked about the doc cycle on coral reefs.

 

[Pistondog]

 

[Lasse]

Do you keep SPS?

Yes but for the moment no Acropora. I have hold gigant clams too. However have had Acropora before without any trouble.

Why does a sulfur denitrator work without dosing carbon? Is the acceptor/donor NO3/sulfur then?

The sulphur denitrification is not a heterotrophic process - it is an autotrophic process - it means it use inorganic carbon sources. It is also done by obligate anaerobs - it means - the bacteria can´t shift between oxygen and nitrate. The acceptor is NO3 - and the donors are sulfide (S2−), elemental sulfur (S0), and thiosulfate (S2O32−)

Sincerely Lasse

 

[Mels_Reef]

Yes, dissolved organic compounds. Algae doc promotes 'bad' bacteria that interferes with coral biome.
Sorry can't find the video, Dr Forest Rohwer talked about the doc cycle on coral reefs.

Yes thanks for clarifying. That article on that study was very informative and interesting. I follow your line of thought in the potential promotion of doc’s from macro algae.

I’d also like to know more about your ammonium bicarbonate(?) process!

 

[Pistondog]

Yes thanks for clarifying. That article on that study was very informative and interesting. I follow your line of thought in the potential promotion of doc’s from macro algae.

I’d also like to know more about your ammonium bicarbonate(?) process!

Just dosing an ammonia source rather than nitrate to keep nitrates up. Some think ammonia is easier for corals to use.

 

[Mels_Reef]

Just dosing an ammonia source rather than nitrate to keep nitrates up. Some think ammonia is easier for corals to use.

Gotcha, I thought you were dosing some kind of ammonia compound to bring nitrates down. I was interested in how that worked! Lol

 

[Lasse]

What i try to say is that you can use DOC to favour denitrification without have and DOC out in the system - if you create target areas for the denitrification. I neither like to dos directly into the water column.

Sincerely Lasse

 

[Mels_Reef]

Quite interesting that their tests showed that the most detrimental addition to their test corals was a carbon source!

 

[Mels_Reef]

What i try to say is that you can use DOC to favour denitrification without have and DOC out in the system - if you create target areas for the denitrification. I neither like to dos directly into the water column.

Sincerely Lasse

So if I’m understanding you correctly you are suggesting I dose a carbon source into the denitrator vs dosing it directly into the water column. That would appear to be a safer way to carbon dose without having all the other strange side effects that I’ve experienced before. I am just leary of using carbon. But this may be a better option.

 

[ShakeyGizzard]

Late to the party, but I assume that the OP is blowing there aquascape off with a turkey baster every week, and vacuuming the sand when doing water changes ? If your not, you are fighting an invisible monster

 

[GARRIGA]

There is
different way to use organic carbon. The most used by aquarist is just to dose the DOC (Dissolved Organic Carbon) into the water column. The other way is the way described in Donowans thread about nitrat destroyer - you dose it into a container of some type of media. This means that you target feed the filter with DOC.

Why would target dosing differ from display dosing assuming all eventually makes it to the media? Unless the assumption being something gets first use of the carbon and utilizes it at which point wouldn't increasing the display dosage not provide the same end result based on measuring influent vs effluent?

 

[ReefGeezer]

Yes, running an old eshopps rated for 350g heavy load. And I skim wet.
I have a 75g DT turned frag tank and a 7’ frag tank both plumbed to a shared sump

Here’s half the frag tank

Sorry, more questions... I don't see any fish. Do either of the tanks have fish in them?

 

[Lasse]

Why would target dosing differ from display dosing assuming all eventually makes it to the media? Unless the assumption being something gets first use of the carbon and utilizes it at which point wouldn't increasing the display dosage not provide the same end result based on measuring influent vs effluent?

If you dose into the media - the right way and with the right dose/waterflow ratio - the DOC will only affect the bacteria population in the media - not in the DT, rocks, sump, corals or whatever. It will be consumed and converted into mainly CO2 in the media. These bacteria is not primary bacteria plankton - they are bacteria that attach to something. You need to create a anaerobic environment in the media - it means that the aerobic bacteria metabolism needs to be very high in the first layer of the media (consume all free oxygen in the incoming water) and you need a little "spill" over of DOC in the other layers of the media in order to have the denitrification process going on. You can theoretical get a anaerobic filter media with help of a very slow flow through the media but the second part - free DOC for the denitrification process will take a very long time to get. You can get it with help of internal production (in the filter) of carbohydrates, alcohols or other labile DOC but it will take a long time before this happens. This is the reason why passive DSB works but have a "starting" time of months, or even years. The flow in these beds is done by equilibrium processes between water in the aquarium and the porewater in the media (in the DSB). The needed labile DOC is produced by breakdown processes in the media (sediments)

You can also get some conversion of ammonium directly to N2 with nitrite as electron acceptor. This process is autotroph - do not need DOC with other words. this process - Anammox - was discovered back in 1990:ties and can be responsible for more than 50 % of the N2 production in sediments around the world. As I know - it has not been shown in aquariums even if I suspect it can take place in my reversed flow DSB cause around 0.4 mg L NH3/NH4 is normally disappearing from my water that flow through my DSB - but I´m not sure because my NO3 will rise in the system if I do not dose enough of DOC. However - anammox can be responsible for the N loss in static DSB - but as I know it - it has not been shown.

I can´t explain exactly whats happens in my reversed flow DSB but it consume N - I can totally control excess nitrate - the end product of the oxygen-dependent nitrification in my aquarium with help of ethanol dosing.

Sincerely Lasse

 

[Mels_Reef]

Sorry, more questions... I don't see any fish. Do either of the tanks have fish in them?

Oh yes…5 tangs, 3 sixline wrasse, moyeri wrasse, ruby wrasse, 2 blennies and a sand sifting goby. The tangs in the frag tank are the main source of nutrients. They’re between 5-6 years old, 5”-7” and happily obese. I feed a 4” x 8” sheet of nori to them every day and broadcast feed a home made shrimp/plankton/blood worm/rotifer blend to both tanks. Frag tank is bare bottom and I have the flow setup to push all the detritus to the front left corner and I vacuum that out every week with a WC. Sand in the DT constantly gets turned over by the sand sifter. He probably rearranges all the sand at least twice a week.

 

[Mels_Reef]

Why would target dosing differ from display dosing assuming all eventually makes it to the media? Unless the assumption being something gets first use of the carbon and utilizes it at which point wouldn't increasing the display dosage not provide the same end result based on measuring influent vs effluent?

My assumption is that the anaerobic bacteria in the media would consume most of the carbon before it exits the reactor.

 

[Randy Holmes-Farley]

Why does a sulfur denitrator work without dosing carbon? Is the acceptor/donor NO3/sulfur then?

Yes. Sulfur is oxidized to sulfate and nitrate is reduced to N2.

 

[Randy Holmes-Farley]

My assumption is that the anaerobic bacteria in the media would consume most of the carbon before it exits the reactor.

Again, I expect crushed coral media in such a reactor will not accomplish much. If you try to make the whole reactor anoxic it will be extraordinarily tricky to keep it from becoming anaerobic and producing hydrogen sulfide. Special media with interior anoxic regions rarely solve elevated nitrate problems. There’s not enough organic around.

The use of the terms good and bad bacteria concerns me. How does one decide which is which?

 

[Mels_Reef]

Again, I expect crushed coral media in such a reactor will not accomplish much. If you try to make the whole reactor anoxic it will be extraordinarily tricky to keep it from becoming anaerobic and producing hydrogen sulfide. Special media with interior anoxic regions rarely solve elevated nitrate problems. There’s not enough organic around.

The use of the terms good and bad bacteria concerns me. How does one decide which is which?

It is a recirculating reactor with a valve on the effluent end. You shut the output valve and recirculate the same water over and over to “cycle” the reactor. If you never open the output, then yes it would end up producing hydrogen sulfide. its an easy indicator if you start smelling eggs near the reactor. At which point you release the valve to drip. My guess is that the non-sulfur media will probably work but not be as efficiently as if you had sulfur in the reactor. But I think I will experiment with it on a QT since I already have the reactor