BurnNSpy

q

Member
On your plenuim in your tank how far under the sand is it and why.
Thanks
 

burnnspy

Active Member
the plenum sit on the tank bottom, it is used to create a water void beneath the gravel. It removes nitrates more efficiently then any other method to date with DSB running a close second.
BurnNSpy
 

q

Member
I was asking how much sand sits on top of the plenium. Rather poorly too.
I have read that after an inch the sandbed starts starts to convert nitrates. So if I had a 4 inch bed would I want to create a 3 inch space under the sand or is the egg crate not stacked on it's self.
I was thinking of having a 4 inch bed with a couple of grids under the sandbed in my 75. Since I have heard pro's and con's of both I figured I would try the best of both worlds by having the plenium come incontact with a large portion of the bed while still maintaing the depth of the sandbed.
 

burnnspy

Active Member
A plenum need 4" of gravel above ot to work properly. Unlike a DSB a plenum denitrates all the way to the plenum because some O2 reaches the plenum in an Anxious(O2 low) state and not Anerobic(O2 free) as a DSB.
BurnNSpy
 

q

Member
Thanks for your patience but let me continue with my question.
Ironreef: It was my understanding that denitrification occurs in Anxious and Anerobic conditions. It is just a different chemical process. Gonna read up a bit more but don't have time until tomorrow. So if I am wrong go easy on me.
BurnNSpy: Let me make sure I understand what you are saying. The plenium is it Anxoius?
The reason I became interested in the plenium for my set up is because of the recent articles in FAMA. The benifits of reducing the Vibro (spelling) bacteria (which is linked to toxic tank syndrome) by a significant amount is worth having one aside form the other benifits. On the other hand there are those that are against the plenium because of nutrient build up inside the plenium. Granted I don't know exactly what the test procidures were for all tanks tested.
To me it looks as if a DSB and Plenium are similar but have some differences. This is why I am interested it trying to support both in my tank so that I have both chemical processes happening.
What do you think?
 

burnnspy

Active Member
Denitrification occurs in both Anxious and Anerobic conditions but it is believed that denitrification is less effecient in Anerobic conditions(DSB). If you want both I recommend a DSB, 4"+ gravel in the main tank and Plenum with 4" gravel in a sump that has a low flow rate to the main tank to maximize plenum denitrification.
BurnNSpy
 

q

Member
Yep, from what I have read it occurs in both areas and anerobic bacteria are less efficient which is why you need the plenium to increase the area for the bacteria.
Having the plenium will give me the desired affects of both chemical manipulations.
 

ironreef

Member
all the books I've read says denitrofication happens deep withing LR and deep within sandbeds = no o2. . Nitrogen cycle happens everywhere. denitrofication = nitrates to nitrogen gas. Nitrogen cycle stops at nitrate. pretty much every good reef book says the same. This is why bioballs aren't as good = to aerobic
 

q

Member
In the past two issues of FAMA they have been discussing the topic. Here is what I am understanding.
3 areas. High Oxygen. Converts Amm and Nitrite. Low oxygen. Converts nitrates to nitrogen gas. And no oxygen. Also dissasembles nitrates.(not sure to what form)
Not disputing what you have said. It is true. The nitrate conversion happens in the low oxygen portions of the LR and LS.
There is just another type of process that happens in no oxygen enviornments.
 

ironreef

Member
I suggest looking in a good book on denitrofication = there isn't much o2 in dsb or inside LR. This is the only place you can convert nitrates into nitrogen gas= you see it in a healthy sandbed the bubbles. Otherwise wouldn't there be bubbles everywhere? denitrification happens in o2 free areas.But whatever my point is plenums aren't better because denitrofication in areas under the bed because they get o2. Not debating plenums or dsb just that point. it happens in area where there is little to NO o2
[ November 10, 2001: Message edited by: Ironreef ]
 

q

Member
This is from the October issue of FAMA.
"Natural Nitrate Reduction can be thought of as the start of the new conceptual trends in aquarium systems. Basically all it involves is providing an environment for bacteria to metabolize nitrate to gain the oxygen it contains. This will happpen with natural substrates like sandbeds and rocks, or man-made materials. But to do so,the bacteria's environment fundamentally requires reduced oxygen, making free oxygen a limited commodity. Notice the introduction of the concept of "reduced oxygen." Denitrification using the oxygen boud to nitrate actually starts before getting into the anaerobic environment. In terms of energy flow in an ecological system, the anoxic environment is more productive than the anerobic."
As stated above by BurNSpy you need a 4 inch bed ontop of the plenium so that it is anerobic. The plenium in turn provides more space for the anerobic area.
So I don't understand how pleniums can get oxygen if they are in an anerobic environment.
 

ironreef

Member
one thing about fama I would concider the source= author. anyone can send an arctle. well maybe not anyone but i would refer to the authors background. I've read some really backworks info from there.Most of my books say nitrate is denitrified by facultative anaerobic bacteria that live in anerobic zones . these occupy the cores of live rock and bottom substrates. the best zone for denitrication is the sand on the bottom of the aquarium. Thats from The reef aquarium. modern corals reef say the same so do the rest. But foget about that IME dsb are easier than plenums and do the samething. Plenums many ppl who had them found dsb did the same and are easier. For a plenum to be done right they should be able to drain the bottom of the tank to rid the water after years of build up. This is why some ppl can claim plenums can crash = realease stuff back into the water or tank. I have no experiance with that just what ppl say. But many ppl have good luck with plenums. I've had them= dsb does the same and is easier. theres no advantage to having a plenum IME
 

kris walker

Active Member
I think some of these posts are resulting from confusion over the use of the words "denitrification" (BurnNSpy, Plato, FAMA, Ironreef), "denitrafication"(Ironreef), and "denitrofication" (Ironreef).
For example, BurnNSpy says (and is supported by Plato) that "denitrification" occurs in both anxious and anerobic conditions. However, Ironreef says that "denitrofication" happens in the same conditions. Ironreef also says that "denitrification happens in O2 free areas". But FAMA says that conversion of ammon. and nitrite happens in an aerobic env. And Ironreef subsequently replies that this information is questionable, and that we should look at a book on "denitrofication".
It seems to me from the other context clues that you all are saying the same thing, but getting hung up on the word being used for the NO3 to NO conversion process and the other processes (ammon. and nitrite conv.). I propose using simple phrases to avoid confusion: nitrate conv., nitrite conv., and ammon. conv.
As I understand, this line in Plato's post is right: "High Oxygen. Converts Amm and Nitrite. Low oxygen. Converts nitrates to nitrogen gas. And no oxygen. Also dissasembles nitrates.(not sure to what form)"
Bioballs should work for nitrite and ammon. conv. They should not work at all for nitrate conv., since they are in an aerobic env. Similarly, biowheels should work for ammon. and nitrite conv., not nitrate conv.
DSB and pleniums should work for nitrate conv. only, not ammon. or nitrite conv., since it is an anxious and/or anerobic env.
post on,
sam
 

ironreef

Member
Denitrofication is when nitrate is turned in to nitrogen gas. The nitrogen cylce convets it all and stop ate nitrate.But wahtever nothing to argue about. I'm just saying plenums doesn't give you an advatage and if the advantage is they have more o2 in the underneath the sand I don't see how? o2 isn't needed much when converting nitrate into nitrogen gas. But thats besides the point. I had plenum for years and saw no advantage over a dsb. I've had bareboton 1" sand plenums not dsb which i prefer.JME/JMO
 

burnnspy

Active Member
SurfinSam, A DSB or plenum system does conver ammonia and Nitrtie since the first 1" of gravel is aerobic and contains aerobic bacteria just like a bioball setup.
The plenum contains a low oxygen gradient, this cannot be mistaken for a DBS oxygen free zone.
There is usually no measurable difference between the plenum and DSB systems except is has been reported that if all conditions are exact the plenum system will support a higher bioload(more fish) before nitrates start building up.
BurnNSpy
 

q

Member
Ironreef: I appreciate your comments and am not trying to argue. I understand the topic better now as a result. The issue about the source=author is an issue that does require consideration and will conceede that I can't qualify the statments and am aware of some disputs as to the qualifications of the author. I also can't disqualify them.
One thing that I did find interisting is the reduction of Vibrios bacteria 20-130 times in a plenum syatem as compared to a DSB.
I will continue to look into the issue. If you could give me a book or two that deals with the subject I would appreciate it.
This topic was fun.
Matt
 
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