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Originariamente inviata da buddha
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Perché nessun batterio lo utilizza in quel senso.. Il fosfato tal quale PO4---, viene utilizzato come merce di scambio tra ATP e ADP per fornire l'energia necessaria per processi di accumulo di PHB o di sua demolizione a seconda della presenza
O meno di substrato organico disponibile.. Se serve produrre ATP il PO4--- e' catturato dall'ambiente se no rilasciato.. E' la presenza
O meno di carbonio organico che fa la differenza..se c'è carbonio il fosfato viene rilasciato..
L'energia deriva dalla rottura del legame tra il fosfato e l'adenosina come nelle nostre Cell mentre per la respirazione vera e propria l'accettore di elettroni finali e' L'ossigeno in fase aerobica e il nitrato in anaerobica.. Quindi abbiamo sbagliato il presupposto.. Non e' l'anossia e L'ossigeno che intervengono sul fosfato ma solo la presenza o meno di carbonio da organicare..
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e quindi la cosa va vista in accoppiamento con il ciclo di carbonio...qui viene illustrato in generale come si sviluppano i vari cicli...la conclusione è un pò sconfortante, se ne dedurrebbe che la sabbia fine serve solo ad evitare circolazione di acqua che farebbe andare il fosfato in acqua visto che viene detto che il dsb è fonte di rilascio di po4 .... boh...
How deep sand beds work
The concept of a deep sand bed is to create an environment skewed to the population and growth of various bacterias. These bacterias will reduce and or cycle various elements of food/detritus/waste.
There are numerous cycles which occur in a deep sand bed, i.e.: nitrogen/phosphate/carbon/sulfur/iron and methane cycles. The cycles utilize most environmental types created by a deep sand bed. The deep sand bed can be broken down into zones. The first so is the aerobic zone (oxygenated) in the second zone is the anaerobic (depleted oxygen) and the final zone is the anoxic (devoid of oxygen).
The first zone of a deep sand bed is called the aerobic zone (oxygenated). In this zone a variety of creatures live, snails, pods, various worms and so on. But the most important critter is bacteria. In this zone bacteria will reduce ammonia to nitrite and nitrite to nitrate. This process is called nitrification and is done by the stealing of a proton or electron from nitrogen based products.
From here through the migration of worms and so on nitrate is passed down to faculative bacteria(batceria that can fix both oxygen and nitrate). As oxygen levels deplete these bacterias change from fixing oxygen to fixing nitrate. Nitrate is reduced nitrate oxide then reduced to nitrous oxide and finally reduced to dinitrogen gas. This gas is then off gassed back up through the bed and into the water column. However if there is the presence of ammonia anywhere in this is all been expectation will not occur, instead nitrate will be converted to ammonium which will then migrate up to the aerobic so and once more will be reduced to nitrite and then back through the cycle once again.
The carbon cycle basically boils down to respiration. Carbon dioxide is reduced via certain cycles to for glucose which is used as energy. This will provide a certain amount of exportation, usually about five to 10% of whatever the input is.
The sulfur cycle occurs in both the aerobic and anaerobic zones. Here the sulfate portions of food/detritus/waste our reduced to sulfur and then to sulfide. Sulfide can be reduced further to sulfide gas in the anaerobic zone. All sulfur products will not be exported but will be continuously cycled with in the sand bed.
In the phosphate cycle the phosphate portion of food/detritus/waste enters the sand bed. It is immediately attacked by bacteria trying to reduce it. With this influx of food the bacteria population will bloom. As the food begins to be reduced and is no longer available the bacteria will begin to die off, once they do this the phosphate that they had fixed is released back into solution. Here usually algae is the first organism to take advantage of this. Cyanobactor and hair algae are usually the first on-the-job, they utilize the available soluble phosphates and begin to bloom themselves, this will continue until they use up all the available food stock. Then once again they begin to die off, at this point bacteria begin to reduce the rotting algae and once again bloom. What you will see is small blooms of hair algae and or cyano appear on your sand or adjoining surfaces, it will then disappear as it is reduced. As you continue to add more and more phosphate to your tank these blooms will get larger and larger until they will not disappear.
The balance of the cycles that occur in the sand bed usually do not have an impact on its health.
The deep sand bed is usually set up by using four to 6 inches of oothlic sand. Oothlic sand is very fine and allows more surface area for the growth of more bacteria. Detrovior kits must also be added to the sand bed. These kits consist of bacteria, worms, snails, pods and so on. These critters are essential to keep the sand bed stared and allow for the migration of food products to various levels in the sand bed. Creatures such as sand stirring stars, gobies, qukes should not be used in a deep sand bed system as they will eat and deplete the smaller above-mentioned critters. Natural selection will also deplete the stock of those smaller critters over time, so these kits should be added to the sand bed every eight to 12 months.
Pros:
if set up correctly and maintained correctly the deep sand bed system will allow for good nitrification and denitrification.
A deep sand bed environment will create a good refuge for smaller organisms such as bacteria, plankton, nekton and larva. Which can be a food source for higher life forms in the immediate area.
A DSB is aesthetically pleasing to many people.
A DSB will add more microscopic diversity to your reef tank.
A DSB will facilitate the harvesting of hair algae and cyanobactor on the sand substrate and adjoining areas. If this algae is harvested it can be a source of exportation.
Cons:
Since a DSB will only export nitrogen based products if set up correctly all other products that enter it will be sunk and stored. This will put a time limit on the functional ability of the sand bed as time goes by.
Since the sand used in setting up a DSB is already saturated with phosphates in the lower regions of the bed with a pH is very low the sand will begin to melt and release these bound up phosphates back into solution. This will also occur through bacterial action. So it will become a source of phosphates as it matures.
With the use of small fine sand, the amount of water flow will be restricted to whatever will not allow the sand to stir up into the water column.
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