In reef and fish only aquariums a nitrate level is desired. One way to lower the nitrates is frequent water changes and following a feeding routine that leans toward the theory 'Less is better'. Many marine salt manufacturers endorse this method. One wonders... why? Salt!
Another way to reduce nitrates is to utilize nitrate as food for Natural Nitrate Reduction (NNR). This is accomplished by buying a commercial or DIY denitrator. Our coil denitrator is feed oxygen rich water via a pump. This O2 rich water enters the top of the unit and is then forced to spiral down through the coiled tubing, (usually 1/4'), until exiting within the bottom center of the chamber. As the water level increases within the body of the unit, the Bio-Balls soon become host to millions of colonies of bacteria that proceed to multiply. As the water reaches the top of the chamber, it exits through the output fitting, not internally fitted to the coiled tubing.
Basically, as the water makes it way down through the coiled tubing, the O2 (oxygen) is consumed by the AEROBIC (nitrosomonas & nitrobacter) bacteria, the same ones that are in your filter plumbing and walls of the tank. These bacteria convert ammonia into nitrite and then into nitrate. This process uses O2 and the levels of O2 diminishes.
Now what? Well, now the ANAEROBIC bacteria begin to flourish in this O2 deprived water. They consume nitrate, not O2. As the water continues to travel it encounters the main interior of the chamber. This is where all the round Bio-Balls provide a high surface area for the ANAEROBIC bacteria to colonize.
At this point there is one last detail... a proper drip rate. A proper drip rate is needed to maintain the dwell-time within the unit (basically the flow rate of the water and the time it stays within the chamber) so the bacteria can consume the nitrates. Too fast a flow or drip rate and your tests will show nitrates (as the bacteria have too much O2). Too slow a drip or flow rate and Hydrogen Sulfides are produced. Hydrogen Sulfide can be identified as that rotten-egg smell. Presence of Hydrogen Sulfide indicates trouble to the inhabitants of the reef or fish tank.
PLEASE NOTE: IT IS RECOMMENDED TO AERATE THE EFFLUENT (OUTPUT) WATER FROM THIS COIL DENITRATOR BEFORE REINTRODUCING THE WATER BACK TO THE AQUARIUM. AERATION OF THE WATER HELPS TO ELIMINATE HYDROGEN SULFIDE AND ALSO KILLS OFF ANY STRAY BACTERIA. A DIAGRAM FOR AN ADD-ON AERATION CHAMBER WILL BE PROVIDED SOON!
Following the plans below should give you a Coil Denitrator which you will not have to feed. Testing of nitrates and hydrogen sulfide is recommended. A drip rate of just under a steady-stream is best. A very fast drip, but a definite drip just the same. Use a small air valve to regulate this on the output tube running back to your aerator or sump.
Following the plans below should give you approximately 50 ft of 1/4 inch coiled tubing. This lowest recommended drip rate is 1 drop per second or 60 drops per minute. When adjusting the drip rate, only adjust 1 drop per minute.
When you have constructed the coil denitrator, first fill with aquarium water. Next shut off the system for 3 days. This step depletes the system of O2. Next place 5-6 grains of granular sugar in the input line. Clamp off the line so you don't have to many bubbles when you reconnect the line. Next start up the system at 30 drops per minutes for 2-3 weeks. After this time, readjust the drip rate to 60-90 drops per minute (DON'T FORGET THIS). Denitrators can take months to cycle so be patient. Continue to test for Nitrates in your aquarium.
This DIY Coil Denitrator is not intended to be disassembled. Once it is up and running the denitrator will last for many, many years without any adjustment. About the only area of attention is the drip valve, which may require cleaning due to salt spray.
Materials:
Canister material = acrylic cell-cast cylinder 1/8' wall thickness.
Canister diameter 4' Canister Height 22'
Buy scrap 1/2' acrylic for bottom plate
Buy scrap 1/4' acrylic for top lid
Buy 1/4' 75 ft. continuous. You may also purchase 1/4' poly-tubing from a hardware store in bulk. 2- Airline tubing connectors (connects 2 airline tubing together or extends the tubing).
Buy 1-2 boxes of mini-bio balls. 1 gal should fill the canister for a 4' dia. 22' tall canister while 1 to 1-1/4 gal should fill the canister for a 4' dia. 24' tall canister.
Buy 1/4' airline tubing
Buy Rio 1700 or similar pump/powerhead. Please don't use a valve on the pump output (run it wide open).
Buy a reducer (reduces 1/2' inch tubing to 1/4' tubing.
Buy a airline adjusting valve for output water drip system.
Buy Weld-On #16 thickened acrylic cement. This fills in any imperfections and sets within an hour.
Carbon cup or similar device to filter out the ozone from the output of this DIY Ozone Reactor.
Ok here is the diagram which will help you in understanding and construction..
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