Lorna said:
Also, think twice about rinsing the sand, some do but most say that the fine grit in the sand is beneficial and will settle to the bottom of the sand bed making it more effective at reducing nitrates as it has more area to harbor the good beneficial bacteria.
I do agree with this in a normal circumstance,
My train of though here though was that because the tank has inhabitant's.
Reducing the dust storm may be easier on there health.
As for nitrates, Under 20 should be fine for your fish and inverts.
Of course the less the better.
For future reference corals are more intolerant of nitrates.
DSB's are a bit of a controversy some claim they work great. Others including
Ronald L. Shimek, Ph. D. in marine biology say that are tanks are to small to reap any real benefits of a DSB.
The reason to remove the CC over time instead of all at once. Is that the bacteria that feeds off the nutrients in the tank live on the surface of the CC.
Removing to many at one time will unbalance the tank. So there is more nutrients being produced then the bacteria can eat. This can cause a "cycle" to occur.