Rcpilot
Has been struck by the ban stick
DSB = Deep Sand Bed
The DSB is typically 6" deep or MORE. 6" is the MINIMUM. There is no maximum.
The DSB is where nitrate reduction happens.
A quick lesson in bacterial filtation:
AEROBIC bacteria live on the top of the sand bed and on the surface of rocks. They require oxygen. Just like most other organisms on this planet. They break down waste into Ammonia. Then they break the ammonia down into NITRITES. They they break the nitrites down into NITRATES. But that is as far as they can go. They cannot process the NITRATES down into nitrogen gas.
This is where the DSB comes into play. Starting at about 2" deep, oxygen levels are beginning to get depleted. The AEROBIC bacteria on the surface and first 1.5" of sand are using the available oxygen to eat and reduce ammonia and nitrites. But after an inch or two--most of the available oxygen has been used up. This is where the sand bed starts to become ANOXIC -- no oxygen.
A totally different type of bacteria can grow and live down deep in the sand. They actually DIE in oxygen. They require no oxygen at all to live and grow. These are the ANAEROBIC bacteria.
Okay, so our AEROBIC bacteria live up on the surface and get plenty of oxygen. They break poop and waste down into Ammonia, then nitrites, and finally nitrates.
The final breakdown would be to break the NITRATES down into harmless nitrogen gas. The nitrogen gas can bubble out at the surface of the water. It's called gas exchange. This is how your tank gets rid of excess co2 and brings in fresh o2. Water movement on the surface is how good gas exchange is achieved
The ANAEROBIC bacteria that grow down in the bottom of the sand bed (no oxygen) will eat the nitrates.
They break the nitrates down into nitrogen gas. The nitrogen gas is harmless and will work it's way out of the sand bed. It will rise to the surface and gas out into the room. It's harmless to people too.
Thats total DENITRIFICATION. 0 nitrates!! 
Cheatomorpha and other macroalgae will also absorb nitrates. Plants (algea, cheato, culurpa, mangrove trees) just happen to rely on nitrates for food. You just toss a hunk of cheato in your sump and let it grow. As it grows, it will absorb nitrates AND phosphates.
A good DSB combined with cheato or other macroalgae will most likely handle all your nitrate problems.
Remember, some of our corals have zooanthelle algae in their bodies. Algae is a plant. Plants can use nitrates as a food source. It's okay to have 1ppm or 2ppm of nitrates in most tanks without SPS or anemones. The zoas and polyps will absorb the nitrates for food. But I'd just shoot for 0 nitrates if I was you. The corals will get enough food.
The DSB is typically 6" deep or MORE. 6" is the MINIMUM. There is no maximum.
The DSB is where nitrate reduction happens.
A quick lesson in bacterial filtation:
AEROBIC bacteria live on the top of the sand bed and on the surface of rocks. They require oxygen. Just like most other organisms on this planet. They break down waste into Ammonia. Then they break the ammonia down into NITRITES. They they break the nitrites down into NITRATES. But that is as far as they can go. They cannot process the NITRATES down into nitrogen gas.
This is where the DSB comes into play. Starting at about 2" deep, oxygen levels are beginning to get depleted. The AEROBIC bacteria on the surface and first 1.5" of sand are using the available oxygen to eat and reduce ammonia and nitrites. But after an inch or two--most of the available oxygen has been used up. This is where the sand bed starts to become ANOXIC -- no oxygen.
A totally different type of bacteria can grow and live down deep in the sand. They actually DIE in oxygen. They require no oxygen at all to live and grow. These are the ANAEROBIC bacteria.
Okay, so our AEROBIC bacteria live up on the surface and get plenty of oxygen. They break poop and waste down into Ammonia, then nitrites, and finally nitrates.
The final breakdown would be to break the NITRATES down into harmless nitrogen gas. The nitrogen gas can bubble out at the surface of the water. It's called gas exchange. This is how your tank gets rid of excess co2 and brings in fresh o2. Water movement on the surface is how good gas exchange is achieved
The ANAEROBIC bacteria that grow down in the bottom of the sand bed (no oxygen) will eat the nitrates.
They break the nitrates down into nitrogen gas. The nitrogen gas is harmless and will work it's way out of the sand bed. It will rise to the surface and gas out into the room. It's harmless to people too.Thats total DENITRIFICATION. 0 nitrates!!
Cheatomorpha and other macroalgae will also absorb nitrates. Plants (algea, cheato, culurpa, mangrove trees) just happen to rely on nitrates for food. You just toss a hunk of cheato in your sump and let it grow. As it grows, it will absorb nitrates AND phosphates.
A good DSB combined with cheato or other macroalgae will most likely handle all your nitrate problems.
Remember, some of our corals have zooanthelle algae in their bodies. Algae is a plant. Plants can use nitrates as a food source. It's okay to have 1ppm or 2ppm of nitrates in most tanks without SPS or anemones. The zoas and polyps will absorb the nitrates for food. But I'd just shoot for 0 nitrates if I was you. The corals will get enough food.
