Lowering Nitrates.

[Gravesj1s]

For the poster asking for a study on liverock and denitrification,I dont have a direct reference but close as it also, pertains to remote deep bucket sandbed theories as well.See below.

-T.K. Anderson 1984 "Diurnal Variations of Nitrogen Cycling in Coastal, Marine Sediments."
From that study:
70-90% of overall denitrification was found in the upper centimeter,the remeinder 10-30% was located 1-3 centimeters

-Ecology and Evolution in Anoxic Worlds. Oxford University Press, Fenchel, T. and B.J. Finlay. 1995.

From this one:
anerobic habitat can be as small as 1mm,aerobic and anaerobic essentially coexist,as little as .08mm distance is suffient for nitrification and denitrification to take place simutaneously.

FWIW- I see no reason to incorporate remote deep sand beds in buckets(calfo method).It seems an inch or so is plenty.

 

[tmz]

The deep sand beds can work better if there is some force to move organic carbon down into the sand. The bucket design is poor. The heterotrophic bacteria that perform denitrification need organic carbon as well as phosphate and nitrogen. Simple molecular diffusion doesn't move any of this very deep into the bed.

Contrary to earlier thinking low oxygen areas can form in relatively shallow sand areas or even in the bacterial mulm itself which is why shallow beds are much more effective than previously thought.

However, deeper sand may work very well with channeling organisms(benthic fuana) or at least some advective current to move C,N and P down into it. Advection occurs when current hits obstacles such as live rock or other structures in the water on top of the sand. The sand grains themselves provide some advection.The change in water pressure that occurs when water meets the obstruction creates an upwelling under the structure and a consequent downward current. Natural reefs work this way. So if you use a remote deep sand bed , I think it's a good idea to at least put some live rock on top of it and bounce some current off it. Generally larger surface area such as in a bin or tank is superior to a deep bucket since most of the sand beyond the first inch or so in a buckett stays quite sterile without some way to move C,N and P down into it.

 

[johno4]

For the poster asking for a study on liverock and denitrification,I dont have a direct reference but close as it also, pertains to remote deep bucket sandbed theories as well.See below.

-T.K. Anderson 1984 "Diurnal Variations of Nitrogen Cycling in Coastal, Marine Sediments."
From that study:
70-90% of overall denitrification was found in the upper centimeter,the remeinder 10-30% was located 1-3 centimeters

-Ecology and Evolution in Anoxic Worlds. Oxford University Press, Fenchel, T. and B.J. Finlay. 1995.

From this one:
anerobic habitat can be as small as 1mm,aerobic and anaerobic essentially coexist,as little as .08mm distance is suffient for nitrification and denitrification to take place simutaneously.

FWIW- I see no reason to incorporate remote deep sand beds in buckets(calfo method).It seems an inch or so is plenty.

Im not buying it. I would have to read the actual study to see how this was measured. In the years I have been keeping fish I am yet to see liverock on its own reduce nitrates, at least enough to be noticable.

 

[Gary Majchrzak]

Im not buying it. I would have to read the actual study to see how this was measured. In the years I have been keeping fish I am yet to see liverock on its own reduce nitrates, at least enough to be noticable.

I have

 

[dreaminmel]

According to what I've read, nitrates are reduced by denitrifying bacteria. Live rock provides more areas of very low oxygen deeper inside for this bacteria to colonize. If the rock is actually live and colonized with the bacteria, there is no way that it cannot help with reduction. I went almost 6 months without doing a water change in a prior setup while running a crappy skimmer and feeding heavily. My nitrates stayed below 5ppm. Colonized bacteria on/in my live rock is the only reasonable explanation I have for that.

However, I can understand that some need to see things in writing that were done in professional studies. Occassionally I have this need as well on certain aspects. I will try to find a link for you.

For now, I found this.
http://www.reefkeeping.com/issues/2004-05/rs/feature/index.php

 

[johno4]

Thanks for the link Mel

"The inside of the live rock would be a good place for them, and it appears that they are probably there (Risk and Muller, 1983). It would seem that the assumption that live rock contains the appropriate denitrifying bacteria is therefore valid."

The fact that the authors of the study are saying that the the bacteria is "probably" there tells me that they proved squat. Im not trying to start an arguement with anyone just sharing my opinion/experience.

I did run a simple experiment of my own, i'll share it with you guys. I filled a 5 gallon bucket with liverock, mix of fiji and totoka rock, and filled it with water from a water change. Nitrates read 30ppm. I put in a heater and pump and let it sit for 2 months. I was expecting that after 2 months the nitrates would be lower in that bucket of water. When I tested the water they were exactly what they were at the start 30ppm. The rock used had been in my tanks for 4years so it should be well established with bacteria.

Well thats my experience although maybe my rock just sucks:worried:

 

[Gary Majchrzak]

Instead of doing a 30 gallon water change a week, doing a 120 gallon water change once a month would have a bigger impact on reducing nitrates.

If you attended the zoo event in Rochester a few years ago, Anthony Calfo did a talk on this subject. He said he would drain his entire tank/vats and then replace all the water.

Since then I've taken the stand of larger water changes rather than frequent changes.

As RandyO already knows, I used to be a fan of large monthly water changes but nowadays I prefer more frequent smaller ones. Obviously nitrates will be much lower IMMEDIATELY after a 120 gallon monthly water change but the net result of four 30 gallon water changes over the course of a month might be more desirable (ie: no significant rise and fall of nitrates over the course of a month.)
Pay special attention to question #8 and it's answer in this reef chemistry quiz:
http://reefkeeping.com/issues/2007-01/rhf/index.php

The one thing that is not taken into account in many water change theory/discussions is the fact that the typical reef aquarium is fed daily and sometimes (as in Neoz's case) fed multiple times daily.

 

[GMaquarium]

I just read this thread five minutes ago and wanted to do a test. I tested nitrate on my live rock tank. This aquarium only gets old water that had been used in at least two different marine systems before, sometimes three. My oldes saltwater before going down the drain is used for this tank. There is no sand, but the bottom has a good layer of gunk from years of use. There is no filtration and the tank gets fed couple times a week with left over fish foods of any kind to keep the founa fed.

double checked with two hobby level nitrate kits, both show 0

 

[Gary Majchrzak]

Well thats my experience although maybe my rock just sucks:worried:

suggestion:
try some liverock that is light yet porous having a large interior mass.
Branch rock and many forms of Fiji rock are excellent for "shapes" but practically useless for denitrification.

 

[johno4]

suggestion:
try some liverock that is light yet porous having a large interior mass.
Branch rock and many forms of Fiji rock are excellent for "shapes" but practically useless for denitrification.

Most of the rock used is very porous totoka rock.


G,what was the nitrate level of the water added?

 

[Gravesj1s]

- John,Hi.

I look at it as we are discussing these topics not as argueing.Its productive to a good forum.
Anyways, there was an artice in seascope that brought the "forgotten" theory of ammoniafication.I cant figure out how to post a direct link so can someone post the pic of this link please,this could explain why you haven't seen a drop in N03.

http://http--img.photobucket.com-albums-v679-ken75459-nitrocycle.gif

 

[Neoz]

Great discussions and I am following along. Let me ask this, do the majority of fellow members here only feed their tank once a day?

 

[GMaquarium]

Most of the rock used is very porous totoka rock.


G,what was the nitrate level of the water added?

I just tested the invert system it is around 20 on the tests, really not as high as i would guess with the amount of food we put in daily. This is where we keep of crabs, snails, shrimp, urchins, starfish and some fish. The water in this system is filtered with a biological filter (bioballs)and has already been used in a reef tank to begin with (I like to recycle). Everyother week or so a large portion of it ends up in the liverock tank.

 

[Gravesj1s]

-Neoz,

Well ,I dont want to speak for anyone else but I feed every other day currently.eventually it will be a much heavier feeding regime outlined- plan in the works already. I dont want to start pirate threading so ill leave it for another thread.Good topic glad you brought it up.:beer:

 

[daveverdo]

From a scientific point of view, multiple small water water changes should have the same effect at reducing waste nutrients as a single larger change with little vairation in other parameters.

The amount of reduction is a standard exponential decay problem. That is multiple the percent REMAINING water for each respective change by the REMAINING water in the subsequent changes.

For example: 5 10% changes versus 1 50% change

Obviously a single 50% change will reduce nitrates and other dissolved ion by that are not replaced with new water by 50% leaving 50% of the nitrate in place.

For 5 10% changes you would have 90% x 90% x 90% x 90% x 90% =59%
So you effectively have 59% of the nitrates that were originally present, not as effective as a single 50% change but still pretty good.

10 10% changes would only remove about 68% of the nitrates.

The advantage of smaller changes is less overall shock to the system.

I will try to find the threads about continuous water changes being effective.

Dave

 

[johno4]

Graves I cant get that link to work. I always thought liverock reduced nitrates just like everyone else. The test I ran really shocked me. I am running an agressive fowlr and feeding 3x per day so I my nutrient levels are going to be higher than most of your reef tanks.

G, I would imagine that the amount of liverock would be a major variable. I'm guessing that your liverock tank is simply a tank packed with liverock. Your liverock tank has a much larger liverock to water ratio than most if not all of our tanks which could be why your seeing such a drop in nitrates in your tank compared to most. Just a thought.

Can anyone guess why the nitrates in my bucket test would not go down? If we all have tanks with large amounts of liverock why do we need to do so much (skimmers, refugiums, dinitrators, ect.) to keep them down? It just doesnt make much sense to me, maybe I am over thinking this.

 

[dreaminmel]

Even if you start out with good rock, over time coralline algae growth will block up many of the "pores". I have a suspicion that this could possibly at least partially explain the commonly seen "old tank syndrome".

As I mentioned before, in a prior setup my nitrates remained below 5ppm without water changes for many months, a crappy skimmer and my fish were well fed. I did not have a refugium, denitrator, etc... So in my experience we don't always need to run all that in order to keep them down. Those things certainly can help though when something isn't allowing the balance to be achieved.

With the bucket test... do you remember what kind of powerhead you dropped into the bucket? I'm just wondering if the flow was such that the bacteria couldn't thrive due to oxygen levels...?

 

[dreaminmel]

Another thing to note... the end product of gases that are created when the nitrate is broken down? Stinky. And I have come across this multiple times when breaking up large pieces of rock.

 

[Gravesj1s]

Graves I cant get that link to work. I always thought liverock reduced nitrates just like everyone else. The test I ran really shocked me. I am running an agressive fowlr and feeding 3x per day so I my nutrient levels are going to be higher than most of your reef tanks.

G, I would imagine that the amount of liverock would be a major variable. I'm guessing that your liverock tank is simply a tank packed with liverock. Your liverock tank has a much larger liverock to water ratio than most if not all of our tanks which could be why your seeing such a drop in nitrates in your tank compared to most. Just a thought.

Can anyone guess why the nitrates in my bucket test would not go down? If we all have tanks with large amounts of liverock why do we need to do so much (skimmers, refugiums, dinitrators, ect.) to keep them down? It just doesnt make much sense to me, maybe I am over thinking this.

-John, Dreaminmel knows how to turn the link to a pic.(hint-hint)
It shows the pathways for the nitrification as we all know(i.e.-NH3/4-NO2 -NO3 but what is not been discussed in this thread is the fact of ammoniafication
a slightly different process leading Nitrate back to ammonia.It is worth looking at if we can get that link to a pic.

 

[dreaminmel]

Dreaminmel knows how to turn the link to a pic.(hint-hint)

Got it. Here ya be...