Deep Sand Bed -- Anatomy & Terminology

[tmz]

<a href=showthread.php?s=&postid=15299773#post15299773 target=_blank>Originally posted</a> by WaterKeeper
Ryan,

There are a wealth of nitrogen fixing organism in the sea and many on land, ie lichens. Also, lighting fixes nitrogen as well as your own lawn a legume. The process is endless and tends to stay in balance but in our tanks nitrogen fixation is something to be discouraged as it is a closed system.

That is my understanding as well but those nitrogen fixing organisms all contain cyanobactera or related diazotrophps which actually do the N2 fixing . Most nitrogen fixing bacteria grow in in anerobic conditions such as in soils and roots and are symbiotic within host organisms not marine environments. Cyanobacteria is the most ubiquitous free living form although it may also be symbiotic. It forms heterocysts which are internal anoxic zones where nitrogenase which needs an oxygen free enviromnment to catalyze N2( nitrogen gas ) does so by breaking the N2 triple bond and then single nitrogen atoms are fixed to hydrogen protons froming Ammonia NH3 and ammonium NH4.

 

[tmz]

<a href=showthread.php?s=&postid=15299884#post15299884 target=_blank>Originally posted</a> by Whys
What would happen if nitrogen fixing were encouraged in our tanks?

Also, can you give me a definition for "fixes" within this context?

I don't know how you would encourage nitrogen fixing in a reef tank. Some rice farmers use cyanobacteria ponds to encourage it and produce ammonia/ammonium to fertilize rice paddies..

Nirtogen is N2, a gas formed by fusion in the stars. It is believed to be the 7th most abundant element in the universe. It makes up over 75% of the earths atmosphere. Its needed by all living things( comprising 3 to 4 % of body weight ) to create proteins, amino acids and dna .But living organisms can't use it as a gas N2. They use it as single N atoms bound to hydrogen. In order for it to bind to other atoms the two nitrogen atoms must be separated. Due to the number and nature of particles orbiting the nuclei ,two nitrogen atoms bind easily, but the the bond known as a triple bound is the strongest in nature making separation energy dependent.

Fixing N2 involves breaking the bond and attaching hydrogen protons.N2 is broken into two N atoms and hydrogen is attached forming NH3/4 (ammonia/ammonium).Nitrogenase is an enzyme which catalyzes the breaking of the triple bound and sets the stage for hydrogen binding to the single N atoms. Nitrogenase is a substance unique to certain bacteria the most ubiquitous of which particularly in a marine environment is cyanobactera.

So more fixed nitrogen equals more ammonia/ammonium. This brings the nitrification/denitrification cycle full circle . Not to be too philosophical , nitrogen fixing is ,as I think of it, a fascinating link in the circle of life in a way.

 

[tmz]

<a href=showthread.php?s=&postid=15299526#post15299526 target=_blank>Originally posted</a> by Whys
I can't argue with you on the facts. They're a bit over my head. But given nitrogen's significant role in biology, I have trouble believing life wouldn't take some advantage of it.

What happens to all the free nitrogen on the planet? Surely it's not all eaten by cyano.

Nothing happens to it . It recycles. Something dies and decays producing ammonia(NH3/4) which is nitrified and denitrified sending off free N atoms which readily bind with another forming N2, nitrogen gas(free nitrogen) which equilbrates with the air around the tank.. An enzyme called nitrogenase unique to the ubiquitous cyanobacteria and related diazotrohps change it back to single nitrogen atoms allowing it to bind to hydrogen and become biologicaly useful in support of life.. There is a reason cyanobacteria is sometimes called primordial slime and credited with enabling life on this planet, in light of it's oxygen producing capabilities and nitrogen fixing ability.

 

[Whys]

Thank you for that, Tom. Very informative and has definitely changed my assumptions on the matter. Still, it wouldn't surprise me if it turned out that N2 is a bit more useful than we realize. I also don't mean to be too philosophical, but how could life overlook something so abundant?

Just musing, not asking.

So to be absolutely clear, to the extent of human knowledge, cyanobacteria is the only life on earth that uses N2? Does this also mean that all otherwise usable nitrogen atoms ultimately works their way up the food chain/web directly from cyanobacteria? Which is to ask, if all cyanobacteria on the planet died, there would be no usable nitrogen?

 

[tmz]

The diazotrohps which include cyanobacteria(or the other way around; not sure of the taxonomy) are the only organisms with nitrogenase as far as I know.

(I am certain human knowlege can offer more than I can and would welcome comments from those who posses and wish to share it. My understanding of microbioology is at the very amatuer level and I hope growing)).

If they all vanished, what would catalyze nitrogen fixation in nature?Or for that matter what would drive photosynthesis and oxygen production and carbohydrate productuion . where they also play a central role?These bacteria are literally almost everywhere in free living and symbiotic states. For example here's a link to a report from 2004 announcing the discovery of symbiont cyanobacteria in corals which was shared by Tatuvaaj in another thread:

http://www.sciencemag.org/cgi/content/abstract/305/5686/997

It is also beleived that even chloroplasts eveloved from cyanobacteria.

Your qusetion referriing to N2:"...how can life overlook something so abundant?"

It doesn't overlook it. Life found away to break the trivalent(triple) bond of nitrogen( quite a feat) via bacterial activity and make it useable for the creation of proteins, dna etc.

 

[Aquarist007]

Thank you Tom --you really deserve the title Mr. Science and should be granted a doctorate in marine biology.

 

[Paul B]

It is also beleived that even chloroplasts eveloved from cyanobacteria.

It is also believed that Waterkeeper evolved from cyanobacteria

 

[Aquarist007]

<a href=showthread.php?s=&postid=15325699#post15325699 target=_blank>Originally posted</a> by Paul B
It is also believed that Waterkeeper evolved from cyanobacteria

I believe you are right as usual Paul:lol:

 

[Paul B]

I knew it :lol:

 

[newtank]

This thread is awesome. Thanks guys!

 

[newtank]

For my 465g build I'm thinking of plumbing each of the two 600gph overflows to it's own 100g rubbermaid sump, filtering through live rock, under a baffel, over a 5" sand bed (roughly 1 square yard. This seems like signifigant surface area and the baffel will encourage good flow (nutrient transfer?) The sand will be very fine and well established as it is coming out of my 125 that has been up for years. No substrate in the DT, all in sump. The over flow from each 100g sump will spill into a 55g containing skimmer, heater, return... I will research macro algea next to determine what to place over the sand beds but just want to gauge opinion regarding two somewhat large sand beds and +/-'s of such a setup.

 

[tmz]

The more surface area the better.

1200 gph exchange is a bit low for a 500 g system around 5x volume is about right.

Fast flow over the sand bed via baffles may help but without some obstructions to encourgae advection or life in the bed to help the nutrients get down into the hypoxic areas it wont do much denitrification , in my opinion.

Putting macro over a bed can create a mess very quickly via algal exudate and the detritus the algae might trap.

Personaly, I would use those 9 sq ft of lighted surface area for bare bottom relatively shallow( 12 inches or so) chaetomorpha refugia. The algae will remove phosphate and nitrogen and the bottom will be easy to clean out from time to time. Pruning the algae back is a snap. The algae will also absorb CO2 and add oxygen during periods of photosynthesis.

If you are set on a remote deep sand bed with green on top you might want to consider sea grasses as the rhizomes will push down into the sand channeling the bed and will absorb some nutrients as well. This option requires high lighting , however.

 

[PRDubois]

Whys,
I just bought a used tank 40b with a 20l sump.
Tank had some hair & bubble Algae so I took all the rock and bleached it. It is now drying and then I am going to let it cycle in a tub before it goes into the clean tank where I will seed it with some of my good Live Rock from my 72gal.

Question is:
I also have a 5 gal bucket of sand that was in the tank. Sand has been in the bucket covered with water for 4 days.
Since I do not know how long the sand has been in the old tank my plan is to.
Take a 2 quarts of the sand off the top of the bucket and save it to reseed the sandbed.
Take the rest of the sand and rinse it out well with tap water and then drain off all the tap water.
Put 4" of sand into the sump (Ref side) and put the rest into the tank to get about 1-2" coverage in the tank.

Put one qt of the sand I saved into the sump and the other qt into the tank to seed the rinsed sand.

I will let the tank cycle and add the live rock from the tub after about 3 weeks.

Does this sound like a sound plan to you?

 

[Whys]

I would like to take this opportunity to highlight the fact that I have been in this hobby for just over a year now. Thus it is entirely fair to say, I'm still a nooby with very limited first hand experience. I learn what I can from others here and do what I can to pass that knowledge on. While my efforts may be of some help, any advice I give may also be incomplete.

That said, your plan sounds good to me, but I don't actually know what constitutes sufficient cleansing of used sand. Simply rinsing in tap may not be good enough. I frequently see others suggest throwing old sand out entirely. That strikes me as wasteful, but I'm really not one to be giving advice on reusing sand.

Anyone else?

 

[PRDubois]

Good disclaimer!

:bounce1: :bounce2: :bounce3::bounce3: :bounce2: :bounce1:

Lets just say I wanted to BOUNCE it off you!

 

[tmz]

The rock may be holding phosphates or precipitated metals . The bleach sanitizes but doesn't remove precipitants. An overnight soak in vinegar and ro water and a good rinse will help.

Personally, I would not use the old sand;not even for seeding. There are just too many unknowns potentially in there such as parasitic cysts ,and spores , metals and decaying organic matter.

 

[tmz]

<a href=showthread.php?s=&postid=15326196#post15326196 target=_blank>Originally posted</a> by Paul B
I knew it :lol:

:lol: :lol: That made my day. I knew there was something uncanny about Waterkeeper's deep understanding of microbes.

Tom, Thanks for posting the link to the Down the Drain article.

 

[WaterKeeper]

I think he has it wrong however. That is a Coliform in Scott's graphic not a cyano. I do shave once in awhile so I am not often fimbriated.

 

[tmz]

I inadvertantly sip the vodka my bacteria need from time to time so I'm not fmebrtiated either.

 

[Paul B]

I usually let the bacteria have the Vodka, then I eat the bacteria. I figure the bacteria in yogurt is good for me so "Inibriated" bacteria would be better