Quote Originally Posted by Flobex
another Q....

ive been told thaht using bio-balls causes high nnitrAte in a SW setup... is this true? if so, what should i use for filter media instead of bio-balls?
Yes and no. Are nitrates created by bacterial action in the bioballs? Yes. Is it supposed to be formed by bacterial action in the bioballs? Yes again. Is the source of high nitrates in an aquarium due to bioballs? No! That's pretty much the reefer version of an old wive's tale.

Bacteria form what is called biofilms on the bioballs where organics, ammonia and nitrite are converted into nitrates. Those same biofilms are formed on live rock, live sand, plumbing, inside skimmers, on the glass, etc. Basically anywhere there is a suitable substrate. I've never seen anyone suggest taking out LR as a solution for high nitrates, but the same logic would apply.

The reason for high nitrates is not the biofilms producing nitrates. Rather it's the lack of a suitable environment for the bacteria that process nitrate in the final step of the nitrogen cycle into nitrogen gas (denitrification). Denitrification takes place in low oxygen areas such as in a deep sand bed and to a lesser extent in the deep pores of live rock. Now we have the sulfur reactor that provides another technology for processing of nitrates but that still relies on providing a low oxygen environment for these type of bacteria to grow.

The folks that are advocates of running bare bottom or thin sand bed rely on another strategy. They try to remove the organic waste in a very efficient skimmer before it enters the nitrogen cycle as ammonia. I'm not sure what happens to the ammonia being excreted directly by the fish in a BB system. No one has ever been able to explain that part of it to me.

HTH