Filtration - Sulfur Denitrator

Nitrates gradually rise in the marine aquarium, an end result of the filtration system. These nitrates can be removed by dilution (sea water changes) and/or by converting the nitrate to nitrogen gas using a denitrator..

SULFUR DENITRATOR PROCESS OVERVIEW 

Water slowly passes through the denitrator at approximately 1 drop per second, giving a low/no (anoxic, anaerobic) oxygen environment. This allows specific bacteria to develop, these bacteria convert nitrates to nitrogen gas which is released to the environment, a by product of the reaction that takes place is the production of sulphuric acid, this acid is then passed over some calcium carbonate/aragonite media which results in the dissolution of calcium that gets added to the tank to supplement calcium levels.

A sulfur denitrator is a simple filter based on the principle that if the correct environment is provided, natural bacteria will convert nitrates into nitrogen gas.

Reaction
2 H2O + 5 S + 6 NO3- ---> 3 N2 + 5 SO4-- + 4 H+ (extract from Randy)


EQUIPMENT

Sulfur denitrator diagram

1. The aquarium water enter an exits the equipment at approximately 1 drop per second.

2. The pump continuously recirculates the water inside the equipment, passing the water over the sulfur beads and carbonate.

3. Water exiting the denitrator will have less nitrate than water entering it.

Notes:-

1. If water flow through the denitrator is too slow or has stopped then sulfur dioxide gas (bad egg smell) is produced in small quantities. Increase start or increase the drop rate slowly.

2. It may take three months for the bateria to naturally develop in sufficient quantites to reduce aquarium nitrate.

3. The protein skimmer should be placed after the  denitirator. Help to remove any noxious gasses created.

The photo shows a sulfur denitrator.