Steve,

Think of a calcium reactor that instead of had calcium based media, but sulfur based media. Get a slow enough flow through the media, the anoxic zone will host the bacteria responsible for reducing nitrates, and viola, a denitrator for your system.

Here's a blurb Delbeek wrote up on sulfur based denitrators a while ago for AFM:
http://www.aquariumfish.com/aquarium...id=3802&search

There are also several threads on them over at RC of course, if you wanted to poke around over there.

Greg, I'm not familiar enough with Zeovit to comment whether it's a similar process or not. My gut instinct tells me it's different though, because I thought Zeovit was supposed to be a fairly expensive (as in, ongoing expenses) methodology, including dosing several things, whereas a sulfur denitrator is in the same "set and forget" category as a calcium reactor -- i.e., a perhaps hefty one-time/initial cost, but the ongoing costs are minimal. But again, I'm basing this on ignorance of the Zeovit philosophy so maybe someone who knows the details can comment on whether it's similar or not.

Steve,

As you can see by Tony's response and Christy's link, (which is an excerpt from Sprung & Delbeek's Vol 3.), their use has been being studied since 1991. They require a break in period while the anoxic bacteria colonize and feed on the sulfur during which nitrites are actually produced. After the initial break in period, they will produce effluent low in nitrates, but rich in sulfate and acidic. This effluent is then run through a calcerous substrate which binds some of the sulfate and consumes some of the acid finally returning to the tank with slightly higher calcium & alkalinity values.

That this system works to consume nitrates isn't in dispute, but there are arguments over how much calcium and alkalinity are replenished. Sulfate is also a byproduct of this system, but I have not been able to find anyone who has noticed this to be a problem. Most people offset sulfate buildup with 20% or so monthly water changes which would be a hell of a lot cheaper than the 25% weekly I have been going through to keep my nitrates down. Most people report that the need for water changes is much less and that the significant nitrate reduction does nothing but promote better system health.

The units themselves are ridiculously expensive for what you get. I was going to DIY until I ran across this one on eBay, but if I was going to need a bigger one I would definitely build one myself. It's simply a reverse flow Calcium reactor you feed from the bottom, the effluent coming out the top. Sulfur beads can be had at a winemaking store for under $5/kg and the calcerous material can be any pebble sized calcium carbonate.

I'm doing another water change tonight to get some nitrate laden water from my tank and get this thing fired up... hopefully when I get back from holidays it will be reading zero and I can put it in the system. I will keep everyone posted. :mrgreen:

Oh ya... from what I've read, ZEOvit kinda works on the same principle but sans sulfur and you have to supply a regular carbon based food source... the pros of ZEOvit are that some trace elements are supplied using this method, but I didn't go too far in depth... I think Ruth was using ZEOvit so she may be able to tell us more.....

Hey! *I* provided the link first! Now my feelings are hurt. :p And it's a Q&A from his moonlighting at Aquarium Fish Magazine, September 2004 issue (I have the printed article). He may have talked about them in Vol 3 as well, but I doubt it's in a Q&A format there.

I stand corrected Tony - That Q&A actually formed the basis for what is written in Vol 3, which goes into much greater detail than anything I was able to find online.

Oh, my apologies for not giving credit where due...

THANKS FOR THE LINK TONY!

:mrgreen: :mrgreen: :mrgreen:

They have a couple articles on the subject in FAMA (just can't find it right now)

Also check out this article:
http://mars.reefkeepers.net/USHomePa...Denitrator.htm

Cheers,
Vic [veng68]

ok I kinda figured thats how it worked but don't you need darkness for anoxic bacteria? or just low O2?

Steve

Allrighty then! I promised updates as soon as I had any...

I did a water change last weekend and tank nitrates were at 20+ ppm ...

I took 20g of old water to seed the reactor outside the system, and set it at a steady drip rate, actual volume not determined as of yet...

Hooked up the reactor Tuesday and so far in 5 days nitrates are already down to <10ppm... I wasn't expecting any change so quickly... Gotta get a nitrite test kit to see if there are any... if not, I'll be plumbing this little godsend into the main system! :mrgreen: Maybe I CAN keep my fish and corals after all! :biggrin:

Steve - ANoxic = sans oxygen... light plays no part in that.

ya I figured that out but it is used wrong..

anoxic is water with no dissolved O2, not to be used for a description of a organism. when talking about bacteria (or an organism) that lives in low or no O2 levels we should use Anaerobic, which means without oxygen. More specifically, it refers to occurring or living without oxygen present.

thats why it has always confused me when people use the anoxic bacteria term as it is not quite right and throws me off.

Steve

Allrighty folks... checked the test water today and it reads ZERO... much quicker than I had even hoped... this puppy is getting plumbed in to the main system tonight, I'm going to run the effluent through my calcium reactor that I haven't been using as well. One bonus is that I have 20g of water that I removed 2 weeks ago from the main system that I can now use again! Woohoo for the salt bill! :biggrin: