barny, mio padre mi diceva sempre che tutto poggia a terra... la piuma e la piramide.
...però con due pesi diversi!
Ti faccio tre domande secche, rispondendo alle quali credo troverai la falla del tuo discorso iniziale:
3 cm di sabbia denitrificano, e lì non ci piove... ma
QUANTO denitrificano?!?
un DSB confinato in così poco spazio riesce a sostenere una fauna bentonica sufficientemente numerosa e varia?
Ricorda che il dsb è una cosa, il secchiello di calfo è un'altra... non applicare le regole di uno all'altro altrimenti fai un macello.
Il DSB non è solo un filtro biologico, è molto di più.
La sabbia messa in quel punto (una conca, o meglio una grotta) rimarrà bella pulita, oppure si intaserà di sedimento una volta accese le pompe?
Posto uno stralcio di un articolo, riguardante la differenza fra DSB e il secchiello di Calfo:
The difference between normal DSB’s and BUCKET DSB’s…Do ‘NOT’ confuse the two, they are very different beasts. A bucket DSB is a ‘chemical’ filter that works solely on the principle of breaking down dissolved nutrients such as Ammonia, Nitrite and Nitrate to free nitrogen gas and extremely fine organic matter that is too small to be mechanically filtered from the incoming water column. It does not rely on a critter population to handle solid matter and keep the bed loose. In the case of bucket DSB’s, the bed is run remotely from the main sump system in a separate container or tank and is fed only pre-filtered water that has had the vast majority of solid particulates removed. Usually by way of a 5micron filter sock or other such fine filter material on the input side. The main aim here is to let the bed function at a bacterial level, allowing it to work chemically without the hindrance of dealing with solid matter breakdown. The filtering effectively stops particulates entering the area which would otherwise clog the bed over time without the presence of a critter population to deal with it. It has commonly been the case that people confuse these two methods and start applying the rules of one to the other. The simple fact is that you cant have your cake and eat it all the time. Suddenly cutting off the supply of solid food to an existing critter based DSB will probably herald disastrous results as the critter population starves and dies back leaving the bed clogged with dead or decaying matter and no way of dealing with it. whereas a Bucket DSB based system relies on diverting solid matter handling to alternate routes, such as the filter on the input, and more reliance on heavy skimming to take up the surplus. Neither method is wrong, nor right, They simply work in different ways and should be treated as such.
Occhio a trasporre le regole di un metodo alla realizzazione dell'altro!