Does live rock remove nitrates?

[sphelps]

Anywhere where dissolved oxygen is depleted (anaerobic) bacteria can use nitrates instead of oxygen to respire. However in order for the process to work you need some kind of electron donor or carbon source such as methanol or ethanol. Or something like that, basically if you rock houses these anaerobic zones then denitrification could occur but not to an effective level without constant addition of a carbon source. This is why some people does vodka (ethanol).

All this theory about denitrification in the aquarium with the use of live rock and deep sand beds IMO is over rated, and I don't think much of any denitrification processes are occurring in our aquariums, in the ocean yes, but it's just not feasible in the aquarium.

[reptile guy]

Out of curiosty how do you dose vodka?

Originally Posted by sphelps

Anywhere where dissolved oxygen is depleted (anaerobic) bacteria can use nitrates instead of oxygen to respire. However in order for the process to work you need some kind of electron donor or carbon source such as methanol or ethanol. Or something like that, basically if you rock houses these anaerobic zones then denitrification could occur but not to an effective level without constant addition of a carbon source. This is why some people does vodka (ethanol).

All this theory about denitrification in the aquarium with the use of live rock and deep sand beds IMO is over rated, and I don't think much of any denitrification processes are occurring in our aquariums, in the ocean yes, but it's just not feasible in the aquarium.

[sphelps]

Originally Posted by reptile guy

Out of curiosty how do you dose vodka?

I believe the rule of thumb is 1ml per 100 gallons.

[reptile guy]

And how often would you dose that and is that what you do with your tank? Would be an interesting experiment even though my nitrates so far have always been low

Originally Posted by sphelps

I believe the rule of thumb is 1ml per 100 gallons.

[sphelps]

Originally Posted by reptile guy

And how often would you dose that and is that what you do with your tank? Would be an interesting experiment even though my nitrates so far have always been low

Daily, it would be better if you could find pure ethanol, but vodka is probably the next best thing. I've never heard of any problems using this method, just watch for new bacteria films, if a film begins to form somewhere is it's a sing of overdosing so cut the dosage down.

It's also better if you can create a low oxygen zone and dose directly into it. A coil dinitrifier can work well for this, these have a bad reputation but they do work but you have to dose the carbon source into them and you need to achieve the proper flowrate.

[mark]

Well LR must do something as I'm BB and test usually 0.0 or 0.2 NO3 (or got a bum Salifert testkit).

[Aquattro]

Originally Posted by mark

Well LR must do something as I'm BB and test usually 0.0 or 0.2 NO3 (or got a bum Salifert testkit).

And I believe this is typical of many (most?) tanks. Isn't it?

[Delphinus]

I beleive it is fairly typical... except for perhaps in more heavily fed tanks at least...

Yeah, I'm wondering about porosity. It's funny that you started this thread because I was basically wondering the same things and the thought had occured to me just today about the rock density.

[Aquattro]

Originally Posted by Delphinus

I beleive it is fairly typical... except for perhaps in more heavily fed tanks at least...

Yeah, I'm wondering about porosity. It's funny that you started this thread because I was basically wondering the same things and the thought had occured to me just today about the rock density.

Well, I've gone through bouts where I've fed really heavy, no change in NO3. Maybe I'm just lucky?

I guess I bring this up now after that comment I saw, and the fact I need to buy new rock in th enext few weeks.

[Aquattro]

Originally Posted by sphelps

I don't think much of any denitrification processes are occurring in our aquariums, in the ocean yes, but it's just not feasible in the aquarium.

So following along this thought, where did my nitrate go? I'm talking about long running systems never showing detectable NO3, even feeding "well" with PE mysis, daily nori, etc.

I like to believe the rock is doing it, but how does the water reach the anaerobic areas within the rock at sufficient turnover to process the entire tank?
And I'm not certain you need a carbon source with these bacteria, now you're gonna make me have to hit the books again.