Sulfur denitrator experiment

[Delphinus]

I've decided to try a sulfur denitrator. I feed my fish generously, so although I do the water changes, do heavy skimming; I tend to run with nitrates.

I had at least two functioning calcium reactors, only one of which I'm running, so I picked up some Caribsea LSM (elemental sulfur beads) and filled the smaller of the two I had (leaving the midsize unit to still run as a calcium reactor).

I guess technically this isn't so much an experiment to see whether a sulfur denitrator will "work" per se (there are enough testimonials to show the theory is sound), in my case it's more an experiment to see if I could use my smaller reactor as an effective remover of nitrate. It's a very small reactor and only holds approx 1/3 of a container of ARM (or sulfur, in this case).

I used the second stage of my midsize calcium reactor, filled with ARM, to buffer the low pH output of the sulfur reactor.

Unit is recirculated with a Mag2 pump, fed by a minijet powerhead in the sump. The output of the first stage is a John Guest style ball valve for 1/4" tubing and that is closed most of the way, in order to produce an effluent drip rate of 1 drop per second.

I put the unit online on Monday evening.

First challenge was trying to find the valve position to create a steady driprate. I find after 24 hours it tends to have slowed, so I might need to adjust the feed pump situation (I'm currently looking for an Aqualifter pump to see if I can produce a more consistent drip rate with that.).

I'm running the unit on my ritteri tank, which, after a recent skimmer problem that I only fixed about a week ago, has rampant nitrates at 75ppm (the anemone can handle it, it's lived in as high as 80ppm in the past .. there are no corals in this tank .. if there were, they wouldn't be for long at that kind of level!! ).

pH in the tank runs about 8.2.

After 24 hours, pH of the effluent had not dropped significantly (8.1).

After 48 hours, pH of the effluent had dropped to 7.8. Tank still at 8.2, so a 0.4 pH reduction already.

After 72 hours, pH of the effluent has dropped to 7.5. Tank still at 8.2.

There is no sulfurous scent to the effluent whatsoever at this point.

My next plans are to, at the one week point, test the nitrate level of the effluent and compare to tank water, to see if there is indeed a reduction.

I also want to test pH before the second stage and compare to the pH after the second stage, to determine how effective the volume of ARM I'm using is at buffering the output of the first stage.

My main concern is to see whether the small volume of media is enough to create the anoxic zone required for the anaerobic bacteria to take hold. Even with a flowrate as slow as 1 drop per second (roughly 10ml/min), I'm concerned this could introduce too much oxygen into the first chamber. Time will tell.

To convert the calcium reactor into a sulfur reactor ... the main difference is you don't inject CO2 into the sulfur reactor. So you need to close off or remove the CO2 injection port. In my reactor it's a T fitting on the pump intake. I decided to leave the "T" in place because I may go back to using it as a calcium reactor and this way I won't lose the T fitting. Instead I just inserted a small piece of tubing with an irrigation dripline plug to cap it off.


Here are some pics:

First stage filled with LSM beads, recirculating; feeding into single-pass second stage filled with ARM.
(The braided hose and green tubing are not related to this reactor. Same for the red tubing, which is my FW topup line...)



A closeup of the feed line into the T, which is capped off on the unused direction (which is ordinarily used for the CO2 feed):

[Psyire]

Nice, I'm in the process of gettings something similar together. (but on a larger scale) Keep us posted!

[christyf5]

Looks good Tony. I'm interested to hear how this pans out

[Joe Reefer]

Cool, what are your initial nitrate readings?

[Delphinus]

The tank I would like to move it to, and keep it on permanently, has 25ppm NO3.

The tank it is currently on, has 75ppm. It shouldn't have gotten that high but ... I guess I've been more or less neglecting that tank lately. Ooops, well anyhow I've fixed it's skimmer, I'll kick off a nice big water change soon, but thought I would take advantage of the high nitrates to see if my little experiment here will work. If it knocks the number down from that high a starting point then we know that this is working.

[Farrmanchu]

Don't you need to "seed" the new sulphur media? Thought there was a special bacteria envolved.

[Delphinus]

There is, but my assumption here is that you create the anoxic zone and the culture will develop on its own, much like any other biological filter, or DSB. "If you build it they will come." That's why there is a "cycling" stage to these things.

[reeferaddict]

Originally Posted by Delphinus

There is, but my assumption here is that you create the anoxic zone and the culture will develop on its own, much like any other biological filter, or DSB. "If you build it they will come." That's why there is a "cycling" stage to these things.

Yes there IS a cycling time Tony... I bought one in the summer and have been running it ever since with great results... I bought a Korralin 1501 with sulfur media and it took about a month before my nitrates started to drop, but once they did, I have had them at ZERO for over 3 months now. I too feed my overstocked tank generously and best of all... no more $100 a month in salt!

[Skimmerking]

Tony sounds good. I hope that i can get one if I can figure out this kalk reactor that i have I may have to fix it into a sulphur reactor too. here is a picture of the kalk reactor.. the one on the right what ya think TOny is it workable.

[Delphinus]

Potentially .. you might end up needing to modify it quite a bit though. The kalk reactor mix path is from the bottom to about partway up, whereas you'd want to fill as much of the chamber as possible with the media, so the mix path needs to go from the bottom to right to the top. The pump may also need to be upped from a maxijet to something stronger.

I'm by no means an expert on the subject though, I'm just trying this out for the first time just to try to figure it all out too!