Any DEnitrifying bacteria present?

[EvilMel]

OK. So I know that our live rock/biological filters are based on the actions of nitrifying bacteria...the ones that convert ammonia into nitrite and then another bunch that converts nitrite into nitrate.

What are your thoughts on denitrifiers? Seems like if there were denitrifying bacteria present (the ones that convert nitrate into N2, which is a gas and would exit the system) that we wouldn't see a gradual build up of nitrates in the aquarium, right?

Anyone have any thoughts on it?

disclaimer: I'm not saying that even if there are denitrifiers present you shouldn't water change. You should water change no matter what!

 

[Fishboy42]

I'm sure that there are lots of denitrifying bacteria living within the live rock and other low-oxygen areas of our systems, but my guess would be that there just aren't enough of them to make a big enough dent in the nitrate levels. I think the idea behind a DSB is to provide enough area for these bacteria to handle the system's nitrate loads. The bacteria might process most of the nitrate in a normally-filtered large system with very few or no fish, but who wants that?! I think lots of people have enough algae, corals, clams, etc that are scavenging nitrate too, so that probably helps keep them low (along with changing water). I could be wrong, but I think all denitrifying bacteria are obligate anaerobes, so that limits where they can live.

-Matt

 

[GPhiAce]

What kind of bacteria is in MB7 and what bacteria do vodka dosing fuel???? I thought that these bacteria are the denitrifying kind and the ones that you are talking about propegating? I could be extremely wrong-- would not surprise me at all.

 

[KafudaFish]

1. They are overpriced pieces of equipment.

2. They work and it has been documented. Most use them away from reef settings.

3. Because more and more people are going for minimal LR that brings the debate up on the amount needed for this stage of the process.

4. Finally as Matt said, the bacteria need the proper environment to survive. If a sand bed is an inch or two and there is little live rock then what?

 

[McCabe0930]

Mel, by no means am I an expert in this subject and I feel really weird telling you something since you have been doing this a long time. But the DEnitrifying bacteria would be anaerobic bacteria. They live in area of the tank where no oxygen is present. They convert the nitrate to nitrogen gas which can then be expelled from the tank. The problem is if too much nitrogen gas is expelled in too short of time it can be harmful to everything else in the tank. If you are seeing small bubbles from your substrate from time to time then you have anaerobic bacteria.

 

[Paul B]

that we wouldn't see a gradual build up of nitrates in the aquarium, right?

Correct, if you have enough de nitrifying bacteria in your tank, your nitrates will not go up.

My 100 gallon reef is very old, I change very little water there are about 25 fish in there and my nitrates read about 3.

So presumably, there are enough of the correct types of bacteria to perform this.
I also add bacteria from the sea.

 

[EvilMel]

Dustin...no biggie. I understand what the denitrifying bacteria do but my query basically is...if they are present in any large amount, wouldn't our tanks read 0 nitrates. I'm kinda arguing against there being any denitrifing bacteria present. You may have stumbled onto something with your comment about oxygen (or lack thereof). I need to check if ALL denitrifying bacteria are anaerobic. I don't know. Seems like denitrification would liberate oxygen.

 

[McCabe0930]

Bacteria

Bacteria

Mel, the denitrifying bacteria are usually ina deep sand bed where little or no oxygen remains. the problem is that we tend to have sand sifters and clean the sand to often so we are allowing more oxygen to get into the sand thus preventing it from growing and becoming a large enough colony to matter.

 

[ct_vol]

Also, sometimes nitrates are not the limiting factor for the "denitrifying bacteria"... This is why some people resort to dosing Vodka or Sugar, or VSV, zeovit, Neo Zeo, etc. etc..... Some bacteria need a carbon source to fuel their expansion and population growth in addition to the presence of nitrates... I beleive that is why CO2 is used in Nitrate reactors...

 

[EvilMel]

Interesting. When I have 5 minutes to breathe I'm going to have to really think about this.

I'm currently feeling overwhelmed.

 

[ct_vol]

Can't understand why...

 

[Bugcrusher]

Denitrifying bacteria

Denitrifying bacteria

Psuedomonas stutzeri, Micrococcus denitrificans, and Bacillus subtilis are the main bugs responsible for this. There are many others but these three carry the water so to speak worldwide. The first two are aerobic (Psuedomonas), to microaerophilic (Micrococcus), to facultative anaerobes, (can grow with out oxy present - Bacillus). In conjunction these microbes will take ammonia to nitrogen gas in/on a deep sand bed and live rock. This is pretty simplistic and does not include some other players that are always present and doing thier thing also, as in chart above.

 

[Steve W]

All of the denitrifying bacteria that are really effective are anaerobic. I've worked with really large systems for this for years - half a million gallon tanks (got nothing to do with reefing). There's been a lot of research on this, and while a few aerobic bacteria will do a little denitrification, it's the anaerobes that carry the freight. The aerobic nitrogen-processing bacteria primarily convert ammonia to nitrites and nitrites to nitrates.

There are lots of anaerobic sites in your reef aquarium that support these denitrifying bacteria: lots of deep pores in the live rock; deep sand beds, microporous filter media, etc. The reason that your nitrates never go to zero though is because you are continuously producing more if you have any significant bioloading in your tank. If you didn't have these bacteria you would be changing water every other day. If you want to further reduce your nitrates, the best way is to add more live rock and sand, and to add commercial innoculants periodically to boost the populations and to use vodka/sugar/vinagar dosing.

I have 40+ pounds of live rock and 20 pounds of live sand in a 24 gallon nano w/ 2 maroon clowns, a 6-line wrasse, a 4" lawnmower blennie, 16 assorted hermit crabs, an emerald crab, a dozen astrea snails, 25 nasarious snails, and a half dozen nerite snails, and 16 assorted hard and soft corals in a 5 month old tank. I feed heavily both to the fish and corals (3-4 times a week for the corals and twice a day on the fish). Yet for the last two months, my nitrates have been consistently under 5 ppm. Now I do my weekly 10% water changes (mainly for phosphate control), but without the LR and LS I am sure that the nitrates would be out the roof. I know they were a real problem for the first 3 months. The only reason I can see that they have come down is the denitrifying bacteria got established and I've been vodka dosing twice a week for the last 3 months.

Steve W. (Chemical engineer)
24 gallon nano w/ 150w MH

 

[macclellan]

> 1 year old thread and the OP doesn't post here anymore.

 

[EvilMel]

But I will to answer this. Just based on general principle...I do not buy the idea that our tanks can support denitrifying bacteria to any great extent. Here's where your argument falls short: our nitrates never go to zero because we're constantly producing more and more crap that is converted to nitrates? Why is it that our nitrites read zero then? Most of us support high enough numbers of the bacteria that convert ammonia to nitrite to maintain zero on a test kit. Seems like we'd also support enough denitrifiers to keep our nitrates low if we did in fact maintain them at all. I just don't believe that conditions in our tanks support denitrifying bacteria.

As far as the species of bacteria mentioned in the earlier posts...those are marine bacteria?!? Really? I've never heard of Bacillus subtilis mentioned in terms of marine systems and I was also under the impression that it was an aerobe.

 

[Steve W]

They never go to zero because the aerobic processes changing nitrites to nitrates are much more rapid than anaerobic processes. Plus aerobic bacteria are all over our tanks but the anaerobes are only in the hard to reach places so it takes longer for the nitrates to migrate into these anaerobic sites. It's just the way it is.

Go to ORNL.gov and research anaerobic bacteria reduction of nitrates. There's a ton of research out there to support this. The government has been doing it for years. Just because it's in a marine environment, doesn't change the kinetics, just maybe which bacteria are active.

Steve W

 

[Runner]

> 1 year old thread and the OP doesn't post here anymore.

Interesting read, but why did somebody with only a few posts dig this one up?

 

[Spongie]

Hmmm Scott is on to something here.

 

[Flavum]

Doesnt the same group of bacteria convert nitrate and nitrite?

 

[EvilMel]

Doesnt the same group of bacteria convert nitrate and nitrite?

Nope...different populations supposedly...or that's what I've been taught in school. It doesn't necessarily mean that it holds for reef tanks BUT what I learned was that bacteria such as Nitrosomonas sp. convert ammonia into nitrite and Nitrobacter sp. convert nitrite into nitrate.

I need to go back and re-read about it because it's been YEARS. I'm sure there are more species that do these conversions as well. Those are just the ones I remember from school.