Nitrate Factory

[Pete H.]

I was reading that biowheels and bakpak skimmer media can increase nitrates in the tank. Is ths true? Is there an additional way to regulate nitrate along with water changes? Trying to decide if the biowheels and skimmer media needs to go.

Thanks!

[xCry0x]

What can happen is that the mechanical filtration aspects, typically filter floss, can get covered in all the junk from your tank, which is a good thing initially. The problem is when you do not change the filter media out or clean it regularly that the accumulated gunk starts to rot.

The same as when people say crushed coral is a nitrate factory; the nitrate factory aspect is when all the dietrus accumlate somewhere and are not removed.

I personally have filter floss over the intake to my return pump, the floss turns brown and heavy with gunk within 24hrs and I try to change it daily. This would be similar to an filter sock at the bottom of an overflow drain or the little carbon filter packets used in the aquaclear filters. They get dirty and need cleaning/replacement.

[xCry0x]

Double post! sorry!

[sporto0]

Originally Posted by Pete H.

I was reading that biowheels and bakpak skimmer media can increase nitrates in the tank. Is ths true? Is there an additional way to regulate nitrate along with water changes? Trying to decide if the biowheels and skimmer media needs to go.

Thanks!

They can NOT increase your nitrates, the nitrogen cycle needs ammonia to be converted into nitrites then into nitrates, it is directly related to the amount of fish waste & uneaten food in the tank producing ammonia. Bio-balls can't produce ammonia on their own so thus they can't increase your nitrates. Here is the real answer, if you had 2 tanks, same size, same bio-load, but one used bio-balls & one used live rock for biological filtration, the tank with bio-balls only would have a higher concentration of nitrates because they don't allow for conversion of nitrates into nitrogen gas which porous live rock can do in small amounts because they can provide small pockets of anerobic conditions (very low oxygen) that support the nitrifying bacteria that bio-balls won't support. That being said, you might find a 0-5ppm difference between the 2 tanks. The best way to keep nitrates in check is to keep a moderate bio-load on your sytem & to perform regular water changes, refugiums with macro algae also help in exporting nitrates as well, but it is an erroneous statement to call a wet/dry or any mechanical filter a Nitrate Factory, it simply is not true. Keep your equiptment clean monthly & they will perform well for you.

[dzfish17]

Originally Posted by sporto0

They can NOT increase your nitrates, the nitrogen cycle needs ammonia to be converted into nitrites then into nitrates, it is directly related to the amount of fish waste & uneaten food in the tank producing ammonia. Bio-balls can't produce ammonia on their own so thus they can't increase your nitrates. Here is the real answer, if you had 2 tanks, same size, same bio-load, but one used bio-balls & one used live rock for biological filtration, the tank with bio-balls only would have a higher concentration of nitrates because they don't allow for conversion of nitrates into nitrogen gas which porous live rock can do in small amounts because they can provide small pockets of anerobic conditions (very low oxygen) that support the nitrifying bacteria that bio-balls won't support. That being said, you might find a 0-5ppm difference between the 2 tanks. The best way to keep nitrates in check is to keep a moderate bio-load on your sytem & to perform regular water changes, refugiums with macro algae also help in exporting nitrates as well, but it is an erroneous statement to call a wet/dry or any mechanical filter a Nitrate Factory, it simply is not true. Keep your equiptment clean monthly & they will perform well for you.

I think you meant denitrifying bacteria, right? A good read on the subject. http://www.google.com/url?sa=t&rct=j...rtFnPkkA5v0Ogw

[sporto0]

Originally Posted by dzfish17

I think you meant denitrifying bacteria, right?

You are correct sir, thanks for catching my mistake.

[dzfish17]

Originally Posted by sporto0

You are correct sir, thanks for catching my mistake.

Ive been wanting to send you a PM about your comment a week ago... very funny and so true.

[sporto0]

Originally Posted by dzfish17

Ive been wanting to send you a PM about your comment a week ago... very funny and so true.

LOL, I'm in RC jail now Dave for 3 more weeks, if you want you can try .......@yahoo.com

[Randy Holmes-Farley]

I believe that there are vaild reasons to describe bioballs and related methods as nitrate factories even if they are perfectly clean, and many tanks may be better off without them. That said, if you have adequate nitrate export methods, you may not have a nitrate problem whether you have such factories or not.

Here's a cut and paste from my nitrate article on why I'd refer to them as a nitrate factory:

Such filters do a fine job of processing ammonia to nitrite to nitrate, but do nothing with the nitrate. It is often non-intuitive to many aquarists, but removing such a filter altogether may actually help reduce nitrate. So slowly removing them and allowing more of the nitrogen processing to take place on and in the live rock and sand can be beneficial.

It is not that any less nitrate is produced when such a filter is removed, it is a question of what happens to the nitrate after it is produced.

When it is produced on the surface of media such as bioballs, it mixes into the entire water column, and then has to find its way, by diffusion, to the places where it may be reduced (inside of live rock and sand, for instance).

If it is produced on the surface of live rock or sand, then the local concentration of nitrate is higher there than in the first case above, and it is more likely to diffuse into the rock and sand to be reduced to N2.

[sporto0]

Assumption 3: Water Moves Through The Rock At Just The Right Velocity To Facilitate Denitrification

This assumption is probably the hardest to evaluate. The major question we have to ask ourselves is, "How does water move through the rock?" One occasionally hears the statement from aquarists that water "diffuses" through live rock, just as one occasionally hears the statement that water "diffuses" through sand. Neither statement is correct. Water doesn't diffuse through either of these substrates. Materials dissolved in water may diffuse from regions of higher concentration to regions of lower concentration, but the water itself doesn't move in these situations. The only time that water moves through diffusion is in the special case of diffusion called osmosis, and in that situation a membrane has to separate the two regions of differing concentrations of solutes in the water. Such conditions are not met in live rock, and there is no net movement of water into or out of it by diffusion or osmosis.

Interestingly enough, it is possible that dissolved materials such as the various chemicals constituting the denitrification cycle do diffuse into and out of live rock; however, it is unlikely that such diffusion moves any significant amount of materials. Calculating diffusion rates into and out of the volume of a rock is complicated and includes such variables as the water flow over the rock, the dynamic viscosity of water, the rock's size, and the diffusion coefficient of the material in question through water. When all of the various parameters are factored in, for the various gases or ions in question, the passive diffusion rates are probably on the order of 1 x 10-4 m2/sec. Assuming a constant concentration gradient, and a uniform porosity such a rate means that gases would diffuse in through the volume of the rock at the rate of roughly a micrometer per second, so that in an hour the gases would diffuse about 3.6 mm, or about an eighth of an inch. If a volume is 10 cm in diameter, gases would diffuse to its center from its outside edge in about 14 hours. However, the gases would move considerably more slowly through the live rock than they would through an empty volume. The small diameter of the passages or pores in the rock would restrict the flow significantly. It is unlikely that the flow rate would approach the estimated value, and even if it did the relative volume of the gases exchanged would be minimal.

For a significant amount of gas exchange to occur there has to be continual movement of the water into and out of the rock. Given the minuscule pore sizes in these rocks, the water movement cannot be generated by water currents outside the rock. The resistance to movement of water in small tubes, such as the pores in live rock, is considerable. The only motive force sufficient to move enough water through the rock, so that it may act as an efficient denitrating site, is the force generated by the animals, mostly the worms, living in their burrows. These worms move back and forth in their burrows and in doing so they move the water in the burrows in a pulsating fashion. Many of the burrows and pores are interconnected, either intentionally or by happenstance, and these interconnections result in water movement into and out of the rock. Additionally, many of the worms and other animals in the rock pump water over themselves in their burrows. They do this to facilitate gas exchange over their gills, but the net result is a significant, constant, and moderate current through the rock. Such a current, coupled with oxygen utilization of animals in the rock, could result in the interior of the rock becoming the efficient denitrification site that it has been thought to be.


Randy, do you find this to be an incorrect analysis? I'm not qualified to challenge your thesis, so I won't, but I will ask this question, even if nitrates are formed on the rock & sand must not they still enter the water column? How would we even be able to test for them if it were a conveyor belt type of exportation? Article Source: http://reefkeeping.com/issues/2004-0...ture/index.php special thanks to dzfish17

I just loathe the term Nitrate Factory, especially because so many non-qualified people love to throw it around like a battering ram without having a clue of what they are talking about, this of course does not include you as I respect your vast knowledge & contribution to this forum & hobby.

[Randy Holmes-Farley]

Originally Posted by sporto0

Randy, do you find this to be an incorrect analysis? I'm not qualified to challenge your thesis, so I won't, but I will ask this question, even if nitrates are formed on the rock & sand must not they still enter the water column? How would we even be able to test for them if it were a conveyor belt type of exportation? Article Source: http://reefkeeping.com/issues/2004-0...ture/index.php special thanks to dzfish17
.

No, it does not need to enter the water column. Some certainly will, but some won't. Nitrate made 1/8" down into live sand or rock is 1/8" closer to denitrification than is nitrate formed on a bioball and hence necessarily out in the water column. Diffusion is all about concentrations. More nitrate 1/8" down means more nitrate reaching 1/2" down (or whatever) where denitrification takes place. Even nitrate formed on the very surface of live rock means the local concentration there is a bit higher, helping it diffuse down.

[rogermccray]

Phew, I feel like I just went to a science class This is great information!

[Pete H.]

Thanks! This info is fantastic!

[WillM]

Originally Posted by dzfish17

I think you meant denitrifying bacteria, right? A good read on the subject. http://www.google.com/url?sa=t&rct=j...rtFnPkkA5v0Ogw

This article is excellent! Thanks for posting

[Palting]

Originally Posted by Pete H.

I was reading that biowheels and bakpak skimmer media can increase nitrates in the tank. Is ths true? Is there an additional way to regulate nitrate along with water changes? Trying to decide if the biowheels and skimmer media needs to go.

Thanks!

Originally Posted by Pete H.

Thanks! This info is fantastic!

Hi Pete. You have to put all the info in the multiple posts above together to find out whether it is a good idea to remove you bioballs or biomedia, or not.

You must have a good amount of liverock and substrate to handle the nitrate loads. You must also have a decent amount of flow, so that there is flow to the deeper parts of your substrate and/or to the deeper parts of the liverock for the bacteria to denitrify the nitrate to nitrogen gas. Denitrifying bacteria are anaerobic and notoriously slow to propagate, so don't expect a quick nitrate drop.

Although I do not contest nor argue the statements by Dr Holmes-Harley, bioballs/biowheels can be used successfuly in a reef tank. I personally have used bioballs in the distant past for mutliple years without issues, and currently have been running two giant biowheels in my sump as my main biofiltration station. I also do 10-15% waterchanges weekly, clean my prefilter floss and pads weekly, as well as have a 20 gallon dedicated refugium to service my 200 gallon system. With this current system and regimen, despite having 14 fish to include 4 tangs that eat a lot and make large poop, I have no nitrate issues ( undetectable with all test kits), and have no algae issues.

So, I have 2 giant biowheels in my system. Should I take them out? What for? The system is working perfectlly. OTOH, I see multiple posts everyday by multiple people in this forum talking about having nitrate issues and having algae problems. And they do not have bioballs/biohweels! So, it's up to you to get all thhe information you can and decide what to do. Simply taking out the biowheels is not a magic cure-all.

HTH!!!

[ken55]

Hello

I'm not in a position to point or counterpoint anybody but I will bring up something that occured to me while following this thread last night and today.

I have bio-wheels as a big part of my filtration system (no sump, all hob stufff). I also have a Nitrate issue. I also had asked roughly the same question as you about a month ago and received roughly the same answers.

However, I am now convinced that my issues are actually stemming from the use of crushed coaral as a substrate when I set up the tank a little more thatn a year ago. Are you using the CC? It is sold in just about every LFS, I can't possibly be the only person who ever bought it.

In about a week I'll be changing up to a larger tank and will not be using the CC this go around. After everything settles down after the move I truly suspect my Nitrate issue will go away. If it dosen't..... well then one more suspect eliminated

[tmz]

For a significant amount of gas exchange to occur there has to be continual movement of the water into and out of the rock.

.It's not the bioballs , sponges, ceramics, etc. ; it's where they are and the continous exposure to highly oxygenated water. This condition maximizes amonnia and nitrite oxidation leaving nitrate. However, nitrate reduction can occur in very shallow areas and on rock surfaces . Deep rock penetration via high flow isn't necessarily desirable.

If you remove bioballs or other filtration media from an aquarium with adequate surface areas for bacteria to colonize which are in areas of lower flow ,the nitrate levels in the water will go down,ime. Doesn't really matter if it's rock ,bioballs, ceramics, sand ,sponge, etc as long as there is enough surface area from it to support adequate bacteria for exports to match import levels(food in particular) in a particular tank.

Whether or not the term nitrate factory is used is semantics. In my opinion The use of the term nitrate factory is apt; these set ups do create nitrate from available fixed nitrogen and oxygen and the mechanics of flowing water. Factories make things from other things,so it's a factory. No one called it a nitrogen factory.
The effectivenes of nitrate reducing bacteria depends upon the oxygenation of the surface area. The heterotrophic bacteria that perform dentirification are facultative . These bacteria thrive in the presence of oxygen or without it it the presence of nitrate. They take free oxygen first and when that's exhausted ,they move on to the oxygen in ntirate (NO3). By removing the O from NO3 ,they free the N to join with another N and form N2 nitrogen gas which bubbles out of the tank. In high flow,high oxygen water , they don't get to the nitrate as high oxygen levels are replensihed faster than the nitrifying bacteria or denitrifying bacteria can use them. In areas of lesser flow and oxygenation they move on to anaerobic activity( ie start using the O from the nitrate).
Anaerobic bacterial activity occurs in very shallow areas even the bacterial mat itself; so it is not limited to the deep inside pores of a rock or deep sand .

[sporto0]

Wow, there seems to be quite a few different opinions on this subject, in my opinion, the term "Nitrate Factory" connotates a negative image which makes the reader think that the bio-media itself is responsible for high nitrates, yes, they act like a factory manufacturing something from something else, but this is their intended purpose, they need the suppliers, fish waste & uneaten food to perform this task & I have agreed all along that a balanced bio-load is all that is needed to achieve a proper balance no matter the implement used for biological filtration. The oceans have detectable nitrate & phosphate levels, sometimes I think we obsess on these nutrients instead of trying to achieve the correct balance in our closed systems & thus fingers are pointed at certain equiptment as the sole blame, when in fact it's due to an overloaded, overfed & sometimes poorly maintained tank. I am not convinced a home aquarium could ever acheive proper nitrate exportation through denitrification on it's own, thus water changes become imperative. I do appreciate the vast knowledge & explanations given here even though there is some contradiction & conjecture, after all there would be no science without theory & inquisitive minds.

[tmz]

It's a nitrate factory. Factories are good,they produce things but not if they make something you don't want. Nitrate isn't a bad thing either; it just is. Water changes don't do much for nitrate reduction long term though I think they are very improtant for many reasons. Many aquaists achieve nitrate lower than .2ppm( upper reef nsw levels) even with heavy feeding.
What contradiction? What conjecture?

[sporto0]

Nobody ever uses the term nitrate factory in a good way, it's always used to condemn a type of filtration, I think you would agree with me on this. There does seem to be some contradiction on how & where denitrification takes place, on the surface, in the shallows, deep inside porous rock, diffusion vs osmosis, is good flow through the rock good or bad, etc.
I am not challenging your statements or explanations, they are very apt & concise but this is rarely the case from nitrate factory posts. I still contend that problematic nitrate levels can't be solved by removing the bio-media, the drop in nitrates would not be that great to overcome truly undesirable levels. I also would like to know why you feel water changes do very little for long term nitrate reduction if done regularly, you are removing water with nitrates & replacing it with nitrate free water. This appears to contradict conventional wisdom & may also include some conjecture on your part, maybe not, I'm listening intently though.

[Triton_Z]

Originally Posted by tmz

Water changes don't do much for nitrate reduction long term though I think they are very improtant for many reasons.

I'm interested in hearing you expand on this opinion as well.

[Triton_Z]

Originally Posted by Palting

So, I have 2 giant biowheels in my system. Should I take them out? What for? The system is working perfectlly. OTOH, I see multiple posts everyday by multiple people in this forum talking about having nitrate issues and having algae problems. And they do not have bioballs/biohweels! So, it's up to you to get all thhe information you can and decide what to do. Simply taking out the biowheels is not a magic cure-all.

Palting,

Thanks for sharing your tank filtration details. I think multiple approaches to handling excessive nutrients and byproducts is the key. Water changes, refugium algae export, turf scrubbers, live rock denitrification, and aggressive mechanical filtration with protein skimmers, etc are all part of a well-rounded approach to water quality.

I have added a 30 gallon refugium recently to my large tank setup looking for another way to keep my nitrates manageable in my tank in addition to regular water changes. I've seen a measurable reduction in my nitrates and less red cyano after implementing this change.

[tmz]

I think you would agree with me on this. There does seem to be some contradiction on how & where denitrification takes place, on the surface, in the shallows, deep inside porous rock, diffusion vs osmosis, is good flow through the rock good or bad, etc

Unfortunately ,I don't agree there is "contradiction" except perhaps by some who don't account for the nature of bacterial activity involved. Denitriying bacteria are facultative heterotrophs. There are many studies that demonstrate depth means little and dentrification occurs even in the mulm. You can search them under denitrifying bacteria,heterotrophic bacteria or facultative bacteria and go from there . It's important to understand the nature of the bacterial activity as it relates to surface area, necessary nutrients( organic carbon, phosphate and nitrate and oxygen) before making assumptions about where and with what optimal water movement denitrification can be encouraged or diminsihed. Denitrifying bacteria make their own hypoxic areaswhere they can function anaerobicaly after aerobically removing the fee oxygen in the a colonized area. That's not contradiction ; it's pretty straightforward.

Never heard of osmosis playing any role ;what do you mean by that? Did you read something about osmosis and denitrification,somewhere?

I still contend that problematic nitrate levels can't be solved by removing the bio-media, the drop in nitrates would not be that great to overcome truly undesirable levels.

How do you know that? Have you measured it?
When the ammonia is oxidized to nitrate on a biowheel ,trickle filter with bioballs or ceramic media in a canisiter filter , the nitrate goes into the water column. If that ammonia is instead oxidized to nitrate on surfaces with less free oxygen flowing around more anaerobic activity by denitrifiers occurs.
Removing the nitrate factory will reduce nitrate in the water column . How much depends on how much nitrate is in the tank , the overall condition of the aquarium and available surface area in it. It also depends on available organic carbon and phosphate which the denitrifying bacteria also need
.FWIW, in addition to my main system I run an independent 65 gallon tank with leathers and mushrooms and a bunch of fish with just a canister filter. When I removed the ceramic media continuous nitrate levels fell from 60ppm to 30ppm with no other changes. That is still high but significantly more tolerable particularly for those corals than it was.

I also would like to know why you feel water changes do very little for long term nitrate reduction if done regularly, you are removing water with nitrates & replacing it with nitrate free water. This appears to contradict conventional wisdom & may also include some conjecture on your part, maybe not, I'm listening intently though.

It's just the practical math. A 15 % water change would drop nitrare form 80ppm to about 70ppm. That would go back up after a few feedings. Nitrate accumulates from food and waste and ammonia respired from fish and some other additives or the water added if it's not ro/di . The accumulation happens when export via denitrifying bacteria or other export mechanisms don't match the amount being added primarily from feeding. I don't like to starve fish btw.. Water changes reduce it but not longterm unless the imbalance is corrected by increasin export or decreasing imports or very large and frequent water changes are done routinely.
If you keep feeding it will just rise up again between water changes.

One step to correct an imbalnce in nitrate addition vs removal would be removal of the nitrate factory.Others include: increased surface area in the tank, skimming, granulated activated carbon, macroalgae refugia, crytpic refugia, organic carbon dosing , sulfur dentirators ,etc.
Frequent smaller water changes are very important for adding depleted major, minor and trace elements and maintaing elemental ratios . They put a small temporary dent in nutrient accumulation too but won't solve a high nitrate problem long term without other adjustments.

So, I have 2 giant biowheels in my system. Should I take them out? What for? The system is working perfectlly.

I wouldn't even think about it if nitrate levels were acceptable for the tank's purpose.

Biowheels, trickle filters and ceramic media in canisters and other devices that provide large surface areas with high exposure to oxygenated water are fine devices. They are very good at what they do which is to support ammonia oxidizing bacteria. These bacteria convert the toxic ammonia(NH3) ammonium(NH4) and Nitrate(NO2) to nitrate(NO3) I use them on quarantine tanks with good results in ammonia control.

Unfortunately, they do not support anaerobic denitrification where the facultative heterotrophs take the oxygen from nitrate leaving nitrogen gas since there is always enough oxygen around in these devices by design to preclude anaerobic activity. There is just too much of a continuous supply of oxygen. But again if nitrate levels are at levels you want for the type oftank you are running there would be no need to change.

Nobody ever uses the term nitrate factory in a good way, it's always used to condemn a type of filtration,

Some folks with reef tanks do dose nitrate; some even set up nitrate factories on an iterim basis to help with measured NO3 deficiencies proportionate to phoshate to assist in the removal of the later. There are a number of nitrate dosing threads on the reef chemistry forum. Any pejorative connotation to the term nitrate factory is by the reader's inference. I didn't see anyone implying that in this thread.For anyone thinking about removing a nitrate factory, doing so incrementally with ammonia monitoring as with media and bioballs,say 25% per week is better than all at once,since you will be effecting ammonia reduction initially and want to give the ammonia oxidizing bacteria in other areas a chance to catch up.

[Randy Holmes-Farley]

Originally Posted by Triton_Z

I'm interested in hearing you expand on this opinion as well.

As folks have mentioned, I too do not think nutrient reduction is the most important reason to do water changes. Almost never does that keep them adequately low, and there are much better ways (organic carbon dosing including pellets and soluble organics, macroalgae, turf algae, deep sand, live rock, skimming denitrators of various sorts, GFO and other phosphate binders, etc)

I show exactly what can be accomplished via water changes and what not, as well as the other reasons to do water changes here:

Water Changes in Reef Aquaria
http://reefkeeping.com/issues/2005-10/rhf/index.php

[Randy Holmes-Farley]

Folks should understand that even if something is a "nitrate factory" in the sense that it produces more nitrate than another method might, that does not mean that one could not have a perfectly wonderful reef aquarium using that method. All you need is sufficient export, and nitrate reduction is really fairly easy these days.

So one definitely cannot use the converse to prove that bioballs and such are not nitrate factories. The fact that great tanks might have them proves nothing about whether they might be nitrate factories or not. The only time the nitrate factory even could come into being a concern is if you DO have a nitrate problem, in which case they may be a contributing factor.