|Topic Review (Newest First)|
|02-06-2013 09:03 PM|
I would think this would be the important part for it's purpose as biomedia. Even if it isn't exactly pumice, if it is similar enough, then people could probably get similar results using much cheaper horticultural pumice.
|02-06-2013 01:43 AM|
|VAtanks||Unfortunately I am not able to tell, both are silica based but since pumice has such a huge range between 78ish percent all the way to about 89 percent. I can not tell, at this point I couldnt even difinitively say my BBQ grill scrubbers are pumice. and am considering removing them. The only thing I can say for sure is the channels or pores under microscope are very similar. El cheapo microscope though so at this point my two samples are in the hands of a geologist adjunct professor. It was suggested I heat both samples to about 800 degrees and if they flow then they do belong to the glass family of compounds.....but that wouldn't answer is Matrix pumice....|
|02-05-2013 10:40 AM|
|02-04-2013 11:31 PM|
Some things that happen in test conditions, do not necessarily happen in nature, and vice versa. On top of that, since nature is not controllable, it makes things even more complicated.
As I mentioned, DNRA is much less common than denitrification. The amounts of ammonia/ammonium being produced would be much less than nitrites/nitrous oxides that would be produced through the denitrification pathway.
So, let's assume that nitrites are being produced; the amount of it being produced would be dependent on the number of facultative aerobic bacteria, which would be in turn based on the amount of anaerobic space there is in the Matrix biomedia (assuming it exists). This surface area would be greatly outmatched by the surface area that exists in aerobic conditions, so nitrification (production of nitrates) would be much more favoured.
With nitrates being produced, water changes will be required (assuming you do not have a planted aquarium whereby plants are uptaking nitrates...).
To my knowledge, in reef aquariums, the production of nitrates is slowed down through the addition/construction of a plenum.
|02-04-2013 11:23 PM|
|VAtanks||Seems its strictly bacterial related only and only in an anaerobic environment specifically pseudomonas and clostridium bacteria. which brings us back to the zero air zone in the matrix, but my follow on question would be, if this is naturally occuring in nature has it been established in a tank? would seem to me outside of trace elements needing to be refreshed would almost eliminate the need for water changes?|
|02-04-2013 11:13 PM|
|VAtanks||Physics major/Engineer...so chem baffles me. Is DNRA bacterial related or is it just a natural chemical reaction based on water conditions?|
|02-04-2013 11:03 PM|
Regarding your link to the article (not a textbook), it points out that "the importance of DNRA in freshwater sediments appears to be minor relative to DNF."
As I previously mentioned, DNRA is probably rarer than denitrification.
|02-04-2013 10:14 PM|
So basically the end result would be N2 in a crystaline form at the soil/water contact point as a result of DNRA? I did find a few more articles one from a text book from 07, still relavant though
January 2008, Volume 87, Issue 1, pp 99-111
Good job Dark, I happen to have gotten into fish tanks not for their beauty but for the science...thanks for fanning the flame.
|02-04-2013 10:00 PM|
Those images show that the process referred to as denitrification reduces nitrates to nitrous oxide (through nitrite) and/or nitrogen gas.
Direct reduction of nitrates to ammonium (ammonia) is done by a process known as "Dissimilatory nitrate reduction to ammonium (DNRA)"
Here is some good reading for more information regarding DNRA.
|02-04-2013 09:25 PM|
|02-04-2013 09:24 PM|
Pictures easier than typing
|02-04-2013 08:16 PM|
Originally Posted by exv152 View Post
A quick search on Pubmed reveals that denitrification generally involves bacteria reducing nitrates to nitrogen through the nitrite intermediary. There are some bacteria that just leave it at the nitrite step (meaning it would be available for beneficial bacteria), while some take it all the way to nitrogen gas.
While direct reduction to ammonium from nitrates is possible, apparently it is rarer than going through the nitrite intermediate.
I still find it hard to believe that an anaerobic environment could exist in a canister filter with good flow and porous media. Now, if it were a plenum, I could see it happening.
|02-04-2013 05:59 PM|
Originally Posted by Darkblade48 View Post
|02-04-2013 05:07 PM|
|VAtanks||CrypticLifestyle, I will find that answer out for you tomorrow night in my Chemlab class, I will take one piece of Matrix and one BBq scrubber into lab class with me and examine it and hopefully photograph it adnd I will post the findings here, I might be able to get some grad students to chem analize it for us too.|
|02-04-2013 05:04 PM|
To further fuel this discussion currently in my FX5 from top to bottom I have filter floss (walmart quilt batting), ring two (Pumice- BBQ grill scrubbers broken into inch pieces) ring three same as ring two. This same set up I use on my fluval 205 for my 29 gallon. I run zero chem and when i clean the filters I rinse tray two one month then tray 3 the following. BBQ scrubbers are 100% pumice, little dusty but a whole box of them i believe was like 10 bucks and filled one whole tray in my FX5.
But to field the question about zero oxygen zones, I would say that since pumice and matrix has pores that pass completely through it, wouldn't it require collection of debris on both sides of the pore to creat this dead zone?
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