Biowheels Bad?

[Kynigos]

I just read a thread where someone brought up biowheels being bad because they're "nitrate factories". Now I've heard this before, but I've never really understood it. From what I understand biowheels are supposed to house beneficial bacteria that break down ammonia into nitrite and then nitrite into nitrate. In this way I'll concede that they do produce nitrate, but it's replacing more damaging chemicals in the tank, so wouldn't this be a good thing? I've heard this on freshwater and saltwater boards for a while now, and while I dont' understand why they would be bad in either type of system, I can see how there might be organisms in the live rock that would fix the nitrate instead of leaving it in the water? If anyone could clear this up for me I'd be very appreciative.


Thank you

 

[Fishbulb2]

The idea is that your live rock will serve the same function as the biowheel and it will also convert ammonia to nitrite to nitrate. This process requires oxygen and leaves the interior of the live rock pretty anaerobic. There, bacteria will grow and further process the nitrates to nitrogen gas. With a biowheel, the nitrates will have to diffuse throughout the entire water column and finally end up within the live rock to eventually process the nitrates. So this is basically disassociating the nitrate production from the nitrate reduction. With live rock both processes occur together and nitrates can be converted to nitrogen gas before entering the water column.
FB

 

[Gooli]

you dont need biowheels in a reef tank or any tank that has sufficient live rock.

 

[Fishbulb2]

Yes, but he wanted to know WHY.

 

[Kynigos]

Thanks for the quick replies! That's basically what I was thinking, but with the details filled in. It's nice knowing why to do something instead of just doing it The freshwater thing still confuses me, but I've pretty much chalked that up to misinformed/confused people, unless someone can give me a good reason to change my mind.

 

[Fishbulb2]

I've never heard it used in freshwater. I've always felt the biowheels were very cool but not necessary once a tank gets cycled. I rarely ever had ammonia or nitrites in my freshwater tanks. i think the way the theory evolved here is with an observation and then an attempt to explain it. So basically, everyone who removed their bioballs from their wetdry sumps started seeing their nitrates go down. So then the theories began and this is what we more or less now believe. I've never heard of the same thing happening with a freshwater tank. I'm not sure where the denitrification would even take place gravel instead of live rock. Basically we need a lot of people to try it in their freshwater tanks and if it works..... well i'm sure we can come up with an explanation. hehe

FB

 

[stdreb27]

I've seen it used alot in fresh water but I don't check my params to know if it really works or doesn't work. Or is a n03 factory or not.

 

[fsn77]

In fw, you want bio-wheels to be a nitrate factory. In sw, there are better methods (i.e. live rock, deep sand bed) to break down waste. Most fw fish are much more tolerant of elevated NO3 levels than the inhabitants of a typical reef tank.

In the vast majority of fw tanks, there is no conversion of NO3 to N2 gas. In a bed of coarse gravel (typical fw substrate), there are no anaerobic areas large enough for the proper bacteria to thrive in order to convert NO3 to N2. NO3 slowly and steadily builds up and is only controlled by a heavy stocking of live plants and/or frequent water changes.

That said, I use a bio-wheel on all of our fw tanks, but none on our reef tank.