well, not on an exam, but let's use this difference for this discussion...

Interesting article. One thing I take away from it is that the process of "cooking" rock may be a good thing to do every few years.

Sounds good. I'll read up tomorrow and be back :)

J

Dr. Rons article although a good read, when it comes to the denitrification it's all based on too many assumptions, how do you create the perfect velocity through live rock? Where do you find rock with a uniform porosity? Way too many things have to happen for this to work.

"it is possible that dissolved materials such as the various chemicals constituting the denitrification cycle do diffuse into and out of live rock; however, it is unlikely that such diffusion moves any significant amount of materials."

Seriously I think the algae growing on your rock is removing more nitrates than your rock along.
For those maintaining zero nitrates without a skimmer, what kind of tests kits are you using?

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.

Actually I believe the difference is anoxic simply means no oxygen as stated but anaerobic means without oxygen and refers more to organisms living without oxygen or replacing oxygen.

I would agree rock does de-nitrify but certainly not the most efficient like a dsb or plenum system. Or my turf scrubber. :smile:

I have seen pics of tanks with very old rock and doing fine. I get the same algae growth on newer expensive Fiji, as my 17yr. old Florida type rock.

How the heck does one take the rock from a full blown reef and cook it. I once also said in regards to rock being changed out after some time, that when I start throwing away rock thats $5 to $10 a pound, that the day I take up another hobby. :lol:

I've always thought that algae plays a more important roll in denitrification than it's given credit for. When I switched from PCs to T5s my nitrates went from 20 to 10, and when I took a DSB refugium with too low of a flow off line it went to near 0. I'm thinking the biomass of algae living inside live rock and sand would be equal to or greater that that of bacteria. Perhaps buying or making rock with an open porous structure is more important for the growth of algae rather than bacteria, allowing light to get farther into the rock.


For anyone considering carbon dosing to increase bacteria efficiency, sugar will work as well as any of the commercial probiotic systems, but the down side is it doesn't come with an instruction manual. If you're not willing to spend a couple of weeks researching it before you give it a try, it's far safer to stick with Zeovit, Polyp Lab etc. which has a dosing regimen already established for you.

sorry for the long read!

I read a non-reef oriented scientific paper once on denitrification and how they perform it in water treatment plants. It's very difficult because there are about 100 strains of bacteria that nitrify and denitrify. Some bacteria convert nitrates back to nitrites, some to nitrogen. The study found that finding the "right" bacteria was difficult and they managed to cultivate the "right" bacteria through collecting soil samples from around the world. (On a side note, that article was talking mainly about an interesting study of using organic cotton as a carbon source for denitrifying bacteria instead of traditional sulphur; they were early yet surprisingly positive results)

Now to our aquariums. Natural "filtration" methods are extremely complex. There was an advanced aquarist article on natural deep sand beds where they tested them with livestock and without. The tests with livestock were VERY unpredictable. I think that can correlate to everyone's experiences with denitrification in their tanks. Some people say it happens, some it doesn't, probably because of the great variance in our liverock and the animals (including microscopic) we have in our systems.

Now going to bacterial products like reef-fresh and zeovit:

I've noticed some interesting results very quickly with zeovit too. 2 days ago my tank was at 5ppm nitrate (salifert kit). I did a 10% water change that day. Tested today (2 days later) and it's at 2.5ppm. I know those are VERY short term results but it makes me VERY excited about the potential of the system.

I think that these bacterial products are doing a good job at taking the organic compounds (phosphate, ammonia, nitrate, nitrite, nitrate, etc etc) and converting them into less/non toxic chemicals that can be removed by the protein skimmer. And then there's zeovit where the mixture of zeolytes is doing something confusing in the mix too. Zeolytes are mostly carbon based which could possibly explain the efficiency of zeovit's bacteria. Zeolytes are being studied right now along with graphite for carbon-based nano-technology.

The results of bacteria products I think are more interesting to me than natrual nitrification/denitrification because of the results I've seen with my own eyes in tanks running a biological supplementation product. I think the real mystery of these bacterial products is that they're proprietary products that we can't really replicate on our own. These companies have already performed a lot of research and figured things out that work. It makes me wonder if any hobbyists will eventually figure out what's "in" zeovit and reef-fresh and the rest.

Oh the fun ones I miss when I am gone.

OF course liver rock removed nitrate, well that is if it is in good condition and the right type. it has to have enough porosity and they type of fissures that can create anoxic areas.

I know when I bought my tank I took 240lbs of established liver rock and put it into a cycling tank with 30ppm nitrates. in 24 hours my nitrates were never seen again.

now what makes bad rock or reduces the amount of nitrate reduction. Coraline algae. the more this covers the more it seals. That is why I think people who do racks for there rock to get by with less rock are just asking for trouble down the road. I personally thing you need to have a substantial amount of rock that doesn't get light that way Coraline can't seal it up.

when I had the stuck heater incident, I had a lot of coral dying in my tank in efforts to save them (was a heavily stocked coral tank and everything died overnight) and still not one nitrate measured as I had enough rock to handle the on slot of ammonia, nitrite, nitrate.

Steve