In the perfect aquarium, nitrate is naturally removed via anaerobic bacteria within live rock, or the sand bed. If there is still residual nitrate, it’s assimilated by macro-algae growing in the refugium. That’s a perfect scenario, and as aquarists, we rarely have things work perfectly. Residual nitrate often accumulates within our tanks. It may be the fault of a high fish load, or perhaps over-feeding. It could be that the aquarium cannot support a strong enough population of anaerobic bacteria, or something is leeching a constant stream of nitrate into the water. Whatever the culprit, nitrate is difficult to totally eradicate from the marine aquarium. To make matters worse, we all know the cost of nitrates, increased algae growth, potential for cyanobacteria, slowed coral growth, coral browning and possible rapid tissue narcosis. In any event, excessive nitrates are bad news for reef aquariums. While a nitrate level of three ppm or under is manageable, many reef aquariums drift into the territory of nitrate readings exceeding 10 ppm. It leads to a host of problems, and is often difficult to correct. Enter sulfur based nitrate reactors. Options to reduce nitrates:
Aquarists usually go through a lot of trouble trying to reduce nitrates. Some add more live rock, hoping to increase the surface area for anaerobic bacteria. Others form deep sand beds, or pack their refugiums full of macro-algae. Some reef keepers install a bio-pellet reactor, or traditional nitrate reactor. Bio-pellet reactors use a bacteria digestible carbon polymer (often called a bio-plastic) to increase the presence of anaerobic bacteria. The bacteria use carbon as a food source, and as they digest the bio-plastic, they also assimilate nitrate. While these reactors are known to work, they have been implicated in cyanobacteria break-outs, if the reactor’s output isn’t directed into a protein skimmer. Traditional nitrate reactors use slow flow rates over the appropriate media to cultivate anaerobic bacteria. A major downside to these reactors is the fact that they need fed a soluble carbon source (often daily). The amount fed is based on the existing nitrate level, and it can be tricky to dose the right amount, at the right time. They are also prone to de-cycling, a process in which the anaerobic bacteria within the filter dies down. This causes a nitrate build-up of organic matter within the reactor, often causing the water exiting the reactor to be laden with nitrate, sometimes in excess of 50 ppm.… More:
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