Filtration type and Nitrates

[MarkD40]

I am a new member to RC and have learned a tremendous amount in the last 2 weeks. I have read several times that certain types of filters tend to elevate nitrate levels. Undergravel and wet-dry filters specifically. I don't undeerstand. For a given amount of ammonia released into the tank, you will get a corresponding amount of nitrate. While a wet/dry may not facilitate the anaerobic conversion of nitrate into nitrogen gas, it does not cause an increase in nitrate production. If you have a DSB and live rock you will still get breakdown of nitrate. What is wrong with a wet/dry to quickly "remove" ammonia and nitrite?

Help me understand please.

 

[Travis L. Stevens]

That is the same principal as biowheels, actually. And yet, they don't necessarily "elevate" them, but rather "concentrate and eventually leach them back out". You see, as time progresses in our closed system, anything that decomposes from corpses to uneaten food, to poop, and any other organic compound will eventually go through the cycle. You may never be able to test the cycle that goes on every day, day in, day out, forever. But no matter what happens, it eventually will break down to nitrates. And if there isn't a proper amount of anaerobic area then you will never break it down into nitrogen gas. Sure, a wet/dry, biowheels, and undergravel filters are great ways to break things down to nitrates, but regardless of however much anaeorbic area that you have, they will always stay in those aerobic areas. Effectively, you will be limited to how low you can get your nitrates down because they will always be in the system. You may never get them below X ppm theoretically. But if you completely eliminate the source (IE take off the biowheels, take out the bioballs, run your undergravel filter in reverse to make a plenum, switch your crushed coral bed out for a deep sand bed or bare bottom, etc), you take out the kink in the loop and will eventually break it down to 0 ppm of nitrates. :thumbsup:

Did that help? Or did I confuse you? I have a tendency to do that to people

 

[auker]

I'm confused

 

[reelfreak]

They become trapped in the wet/dry and are never converted, eventually releasing themselves back into the water elevating the levels.

Whether it seems sensible or not, it is true. I watched my sytems nitrates drop from 100ppm on bad days to 10-15ppm on bad days, after removing (slowly) my bioballs....HTH