What is the exact Denitratification process, and what are all the options?

How have all of you conquered the nitrate overtaking? I am currently in a slight battle now. I have a few bio-balls left to be removed, and I will be adding a thicker sand bed in a few days...just as soon as I can get my new stand built.

Well, first of all, removing the bio-balls and establishing a deep (4" or more) sandbed are giant steps in the right direction. [img]/ubb/smile.gif[/img]

Denitrification is the final step in the nitrogen cycle. This is the process whereby denitrifying bacteria, in the absence of oxygen, reduce nitrate to nitrogen gas, which escapes to the atmosphere.

Of course, the first step is when the ammonia is oxidized to nitrite by Nitrosomas which use oxygen in this process. Then Nitrobacter oxidizes nitrite to nitrate. Those first two steps require oxygen (they are oxidizing). The final step (denitrification) is the one that takes place in the absence of oxygen. In fact, a lot of activity takes place right at the boundary between the aerobic and anerobic layers of the live sandbed. (I figured all this out by reading stuff written by 'Biogeek' Rob Toonen -- interesting stuff on sandbeds.)

So, the key to success, is lots of live rock and at least 4" deep live sandbed. [img]/ubb/biggrin.gif[/img]

Ninong

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Irrational Exuberance

As a beginner I have the benefit of not having invested in bio-balls and other stuff... granted our nitrate levels are barely detectable as yet, but we have installed a refugium (a really nice unit from Inland Aquatics) and plan to grow lots of algae.

The sand bed is 4" deep at deepest on the right half of the tank, and just barely there where the live rick is built up, on the left.

I'm looking over the ATS (Algal Turf Scrubber) technology... we're not ready for that yet (or the great expense, since it's new). But we'll see.

Question, is there any way to tell where the anaerobic layer begins, especially since I have a cross-section available, namely the front glass?


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Cheers,
Rob
New York City

PS This morning I tested the water again. Although the Aquarium Pharmeceuticals kit is a cheapo, and colours only resemble the chips in the book in a general sense, nitrAtes have fallen from low (<5) to undetectable in the last few days. What could have caused this? It's not like I changed the water...

Have already tested the Ammonia tester... it will respond to minute quantities (a drop) of Windex dissolved in tank water (5ml). I wonder how I can test the nitrAte tester, against some known nitrate source... a hot dog? Blah! Haggis and Naps perhaps?

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Cheers,
Rob
New York City

Hi Rob,

How do you like the drop-in refugium from Inland Aquatics? Did you get the small one or the larger one? I'm interested in one of those myself and would appreciate your feedback. [img]/ubb/smile.gif[/img]

As far as your nitrates go, it's probably just your sandbed doing it's job. [img]/ubb/biggrin.gif[/img] How long has your tank been up?

The boundary between the aerobic and anaerobic layers will show up as a dark line that will fluctuate up and down a little over time.

HTH [img]/ubb/smile.gif[/img]

Ninong

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Irrational Exuberance

Rob,

The refugium is a great idea, we love ours. It is more for maintaining the diversity of your sandbed than algae growth, since the small size will limit the amount of light that will hit the caulerpa. We keep some Caulerpa in ours, but when it grows too thick, the top part is susceptible to red slime from being exposed to air. It needs to be frequently pruned to prevent this. However, there are tons of spaghetti worms, mysis, gammarulis and more creatures livin in there, which will sometimes wash over the overflow into the main tank and then live in the sandbed until eaten. So, the main reason for the Refugium, is to prevent depletion of sanddwelling creatures, hence its name. The ATS is really not so new, they have been in use at places like the Smithsonian for many years. We have one that we love, and I would like to convert all my systems over one day (if I could just get my Mechanical Engineer husband to help me build them!).

I would go with an even deeper than 4" sandbed if possible, since it gets shifted by fish, and there is so much to see in the sand, it can be as interesting as the rest of your tank. I think a deeper sandbed also correlates to greater tank stability. Be sure to add your sand slowly, so as not to kill off the live sand you have.

Dear Ninong,

> How do you like the drop-in refugium from > Inland Aquatics? Did you get the small
> one or the larger one? I'm interested in
> one of those myself and would
> appreciate your feedback.

It is first-rate workmanship. However it is a lot different than in the drawing. When I ordered it, I confused height and depth, so we are having trouble placing it in the main tank. Also the salesman forgot to tell me that it didn't come with the tiny mini-pump, so I will have to either order from them again or find one locally.

The nozzle from this pump looks like it came off of the space shuttle. You can aim it anywhere... which means that you can locate the pump remotely, out of sight somewhere. That is a definite plus!

However, the only place that this big BOX will fit, is in the sump. Fine. I can even use a bigger tank for the sump. However, the only place I can put this sump is BELOW the main tank.

The problem then becomes, is there a return pump that I can use, that will gently pipe the little critters that spawn in the refugium upstairs, without killing them with shear forces?

> As far as your nitrates go, it's probably
> just your sandbed doing it's job. How
> long has your tank been up?

Six weeks, and the sandbed has been in for three. Sorry to sound so crazy... I simply have nothing to relate my experiences to.

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Cheers,
Rob
New York City

Dear Mermaid,

How was the trip?

> (if I could just get my Mechanical
> Engineer husband to help me build them!)

I sympathise. I program computers for a living, but haven't been able to get it together to fix the home computer yet, so that Tanya can use it... ;-(

There're three inches of sand in places... all of which lies atop an inch-thick layer of crushed coral. Maybe I'll add more, slowly.

I'm really looking forward to watching the sand life develop!

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Cheers,
Rob
New York City

Hi Rob,

The trip was great (cousin's wedding, seeing family...) but the LFS stops were heartbreaking! I saw almost every fish on that list to avoid that is floating around on another board. I was so upset. I did meet Gary at Harbor Aquatics who was awesome. His place was neat too. Tried to go by Splash of Life (2 hrs away) twice, but the first time, nobody would answer the phone, although the message said they were open, so we went out and tried to find it on our own - no luck, still not answering phone then, so we had to go home. Then they returned my first call that afternoon, we arranged that we would be there the next afternoon before 5, bumped our dinner reservations back to squeeze in the trip, and got there right after 4, and they were gone! My hubby who is usually so sweet, was livid. We had dragged his parents 2 hours out of the way, on a jam packed vacation as it was - for nothing. Then, the wife said she would have them call us, but it has been over a week now, and no call. Lesson learned.

I know what you mean about the cool output nozzle on the Refugium - I think it is called a Flex Hose. I like it too. Our Refugium was also different from what we expected, and did not fit our tank either, when added with the ATS we also got from them, so they had to redesign it to fit, since we bought the tank specifically for those two components in the first place. Our real problem was the better quality, wider center brace on our Oceanic, since they had All Glass tanks, they had more room for stuff hanging on the tank, due to having the smaller center brace. If you need the correct pump for yours, I can send you one like ours - we run a MiniJet on it. Also, it is important to let gravity take the critters back to the tank, since I know of no pump that would not kill most if not all of them. Is there any other way you could set this up? I would grow Cauerpa in the sump, and keep the Refugium for sandbed critters, but be sure it is waterfalling into the tank, with no pumps to kill the fauna. Remember you can email me if you have any questions and I do not get to check back here soon.

Rob, you ask about a way to test the nitrate kit. I don't know if it would work or not (I'm at work and can't try it yet) but plant fertilizer should have a lot of nitrate in it if you have any of that you want to test like you did with the windex. BTW, good quality control measure. [img]/ubb/smile.gif[/img]

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Shelly

well i have deep sand beds and i never see the 0 nitrates others report my tanks stay around 5 and sometimes go to ten. but i like them to stay at 5 anyway cause of my clams.
nitrates are a trade off some are good in my opinion over 10 would not be good i have seen tanks that are excellent that run at 20 nitrate so go figure. give your sand time to liven up and your cycle will stablize

hate to say anything, but all i have is a wet dry on my 120 with bio balls, and it looks greeeeeeeaaaaaaat.


drunken Jade