Sulfur denitrator experiment
 

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!! :eek:).

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...)

http://members.shaw.ca/hobiesailor/a...enitrator1.jpg

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):
http://members.shaw.ca/hobiesailor/a...enitrator2.jpg

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

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

Cool, what are your initial nitrate readings?

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.

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

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! :mrgreen:

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.
http://i38.photobucket.com/albums/e1...erfield009.jpg

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!

Day 6 Readings:

Tank pH - 8.2
Tank NO3 - 75ppm (Salifert)

Stage 1 effluent pH - 7.3
Stage 2 effluent pH - 7.6

Stage 2 effluent NO3 - 50ppm (Salifert)

Just to eliminate "testing error" (since I only did one sample for each reading above) I'll test NO3 again tomorrow using a different test kit. The original readings I took, were done with an Elos NO3 test kit, so that's what I'll use again tomorrow to see if I can confirm the apparent reduction already at this point.

Anyhow this is interesting stuff. Just under a week and the effluent coming out of the reactor appears to have a lower nitrate value than the inflow. The second stage, for buffering the low pH output of stage 1, does appear to have some function although not as profound as one might like (0.3 difference? better than nothing I suppose). Really is there a difference between dumping 7.3 into your tank versus 7.6? The drip rate is about 1 drop per 1-to-2 seconds so it is a very slow throughput.

Nice results so far!

I would think the 2nd stg will work better once the bacteria is established in the sulphur stage... The difference in pH should grow as more and more CO2 is produced by the denitrifying bacteria.

Day 10 Readings (Thursday, forgot to post right away)

Tank pH - 8.2
Stage 2 effluent pH - 7.5 (didn't measure stage 1 effluent)
Tank NO3 - 75ppm? 60ppm? Had a REALLY hard time guessing how pink the reading was.
Stage 2 effluent NO3 - Hopelessly unreadable. Seemed like less but cannot be sure.

I hate test kits. :( Going to try again in a few days.

And I broke my vial for the Elos test kit so these were done with Salifert. Did I mention I hate test kits???

Unfortunately it's too late and too expensive to ask Santa for one of these, but how cool is THIS thing?
http://www.jlaquatics.com/phpstore/s...uct_ID=pp-mno3

Um .. eh heheh, anyone got one they'd care to lend me for a couple days??? :D

Guess I know what I'm saving up for now .. next toy :)

Interesting. Our LFS, SWC, has had good success with denitrators.

FWIW I have a BB tank and a good skimmer and 23 fish including 5 tangs, and I feed two tablespoons worth a day and can never even get detectible nitrate readings in it.

I do get about 10 ppm in my coral QT though.:sad:

10ppm isn't too bad. I don't know if it's my ritteri or if it's something else. On this 115g I also have my Calfo-recommended-DSB-in-a-bucket (which is a joke BTW, don't ever bother trying one of these). Both were in a 90g previously ("both" as in "the ritteri was in the 90g and the RDSB was run on the 90g) and that tank too, also had chronic nitrate problems. (And when I say "chronic nitrate problems" I mean "readings very consistently above 30ppm". I'm not sure how I managed to let this tank get to 75ppm, I really let things slide apparently :( ) Whether it's the ritteri that puts an incredible bioload on a system, or the RDSB is itself a source of nitrate due to something or other bound to the sand itself, I can't say .. both theories seem equally plausible to me at this point. I would have to check my tank logs because this goes back quite a few years now, but I think that there is a pattern of whatever tank I keep my ritteri in, tends to have higher nitrates than my other tanks. But this could be coincidence, it could also be due to the fact that these have always been secondary tanks and as such, not running as high-dollar-value equipment as the primary tanks usually get.

My next tank will be BB altogether. I'm happy to hear the positive results with BB, very encouraging.

BB is just soooooo much easier and cheaper and easier and cheaper and you get the point.:wink:

Yeah, I get the point. :D

I had wanted to have "one tank with a little bit of a sandbed" so I could keep things like my open-brain and plate coral properly (I feel these guys do better on sand). Although at the moment I guess it's a moot point. I lost my plate coral when I was in Hawaii because the Tunzes buried it in sand and my tank-sitter didn't notice and it never recovered, and the xanthid crabs totally went nuts on my brain one day and it too never recovered. Now I have a cube tank with a bunch of rocks, a 20" anemone, and a dozen crabs. I can't keep nothing but the anemone in there and it .. sucks. :( I would like for it to be a softey tank one day but I have to figure out how to de-crabbify the tank, I can't *beleive* how many of them came in. The thing that really gets me is that I inspected *each* rock closely before putting them in the tank.

Guess this is turning into a bit of an off-topic rant now.. oops.

Anyhow I'm curious about things like sulfur denitrators and Zeovit. For me, to try this was $25 in ARM sulfur beads versus $300ish to get started on Zeo. Seemed like a no-brainer but I would still like to consider Zeo or Ultralith one day, but maybe in a few months once I get a couple other things settled first.

Day 14

An interesting and potentially discouraging development. :(

Tank NO3 - still @ 75ppm (guessing, the colour pink does not match any on the chart, going on a guessed intensity)

Reactor effluent NO3 -- instantly off the chart. The colour readings only go up to 100ppm and you're supposed to wait a few minutes for the colour to develop, but the colour was well past the 100ppm right away when the drops of the second reagent were added.

I'm not sure what the next step is. Is this the reactor just cycling? Or is it a failure? :( I don't know how much faith to put into this thing to guess how long I should wait before taking it off.

Feeling mighty discouraged ... :(

If I could make up 120g of SW I'd just do a 100% water change at this point. I don't know what to do.

Check your reactor effluent for Nitrite, if it's still cycling then you should have a reading I would think.

Good idea, thanks .. I'll have to see if I have a testkit that can tell me nitrite. I think I had one at one point but I think it might have been my Seachem testkit and I've finished that one a long time ago. :( Hate to buy ANOTHER test kit (have I ever mentioned I hate test kits?) but that may be what I have to do..

I'm guessing your still cycling the reactor. Exactly 2 weeks would be about the time Nitrate spikes. (give or take 1/2 week)

I wouldn't do anything rash except maybe slow down the flow through the reactor if it's faster than a drip/second.

If you are still showing such high nitrate a week from now, then I would start to worry.

Double check to make sure your recirc. pump is running properly.

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I might be coming into this a bit late Tony, but I have a pintpoint monitor that you can borrow if it will help.

I'm curious about something. This sulpher denitrater media, isn't it supposed to absorb NO3 kind of like a PO4 sponge? If so, why would there even be a cycle at all. I understand that it acts as a biological bed so technically there should be a cycle, but in removing NO3 from the equation shouldn't you eliminate the cycling process? Or, is it merily a substrate for concentrated colonies of anerobic bacteria to denitrify the water?

It's the latter case Danny, i.e., it's a substrate for anaerobic bacteria to take hold. I expected it would take some time for the bacteria to take hold, but I didn't expect that it would take hold with the nitrate-producing bacteria (which I thought was aerobic) first. The pH in the reactor went down within 2 days so I thought that meant it was an anoxic zone at that point, meaning from that point forward it would be the anaerobic bacteria colonizing the sulfur beads. I guess it's going to progress through various spikes but now I wonder if I should move the reactor off my tank and instead run it off a bucket of old water change water just to make sure I'm not dumping NO3 and NO2- into my tank unnecessarily (which I assume is not so good for the tank inhabitants!)

I'll send you a PM about the monitor. Thanks!

http://deltecaquariumsolutions.com/d...actors_000.pdf

Deltec is indicating that you need 3 month to cycle the Denitrator!
Quote from manual.
"Note that the flow rates shown above maximum rates and are only achievable when the reactor has been fully
matured for over 3 months and is operated in full automatic mode with a water temperature of 20-30 C."

Wow 3 months. I was reading through the instructions for the Midwest Aquatic's version as my guide. If there's mention of a cycle time that long in there then I've overlooked it.

I guess it makes sense to take a long time for the right bacterias to colonize...

Wow though, that's a long time to wait .. Guess I'll stop posting my updates every few days that's just not gonna work out as an interesting thread.

"Day 300 reading ... everything is the same as before"

It has been very interesting, hope to see this project going.!
keep us up dated.
thx

Midwest Aquatic's Sulphur comes with bacteria pre-installed. 'so to speak'

I should have my new unit soon, and I plan to just add some bacteria from my 'Polyplab Reef-resh' kit directly to my reactor in order to speed things up a bit.

3 months does seem excessive though...

Would it take this long for DSB anerobic bacteria to establish themselves?

I imagine it might.

3 months .. I had no idea. I thought reeferaddict saw results sooner than that, so I'm still hoping there's hope.

Seriously if I have to wait 3 months to see an effect, I'd be better off doing a 100% water change and taking this thing offline. 75ppm is WAY too high to live with. Tank looks like crap too .. I dunno. Feeling a bit bummed out about this.. :(

I didn't realize the Midwest unit came with bacteria seeded media. I missed that. I should have used that stuff instead of the LSM then. :(

My results took about a month to develop and have been very consistent since. Before I did the denitrator I battled hair algae and the sort for a year and a half. The tank now runs a tidy ZERO and that even with not getting to a water change in 6 weeks now.

The sulfur does need to colonize denitrifying bacteria in an anoxic environment. To do this I ran mine on a rubbermaid of 80 ppm tank water with a slow drip rate to begin with to promote the anoxic zone and gradually ramped it up to around the 5X media volume turnover per hour as stated in Delbeek and Sprung Vol 3 and waited to see my test water nitrates drop. I noticed a drop after about 3 weeks and after a month there was no nitrates left in the test water. During that time I had gotten the main system down to a reasonable 20 - 30 ppm. It took about 6 weeks on the main tank before my nitrates really dropped, but after 2 months there were ZERO which is where it's been ever since.

You need to keep an eye on the effluent rate, as I've had mine clog a couple of times and when you start up you get that wonderful rotten egg hydrogen sulfide stench, but even restarting it in the system doesn't release enough to be of concern to the inhabitants. I've seen nothing to compare to the nitrate elimination potential of this system. For the most part it's set and forget when implemented with a little research and common sense. Be patient - about all I can say is you may want to try increasing your effluent rate and see from there. I was dauted by mine at first - but it works beautifully! :mrgreen:

Reefkeeping rule #7234 - Nothing good happens fast. :mrgreen:

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**Insert Bacteria Here** :lol:

Tony, why dont you do a nice sized water change, and then run the unit out of a rubbermaid. Sounds like a good idea to me.

and more so when your married

Have you checked the calcium level out of the 2nd stage? In theory, with the sulfer producing acid, this may be a replacement for the CO2 bottle in a calcium reactor, or a least be of some value for calcium replenishment even if the goal isn't NO3 reduction.

Not yet. Randy Holmes-Farley did this article about sulfur denitrators where he showed the chemical reactions happening and demonstrated how the calcium and alkalinity, although there will be some, won't really be a significant source for the tank. However I'm sure it's still better than having nothing.

How did you ramp it up? I'm still running about one drop per 2 to 3 seconds. Could I start opening it up at this point?

I don't have vol3 yet. I dropped a pretty big hint to Santa though.

So ...

5x media volume. I'm using a 4" reactor and my media height is approx. 8.5".

So roughly PI * 2^2 * 8.5 (Pi * r^2, where r=2 because diameter is 4") = ~107 cubic inches

1 cubic inch = 16.387064 millilitres

Therefore 107 * 16.387064 = approx. 1750ml

1750ml * 5 = 8750ml/hour

8750 / 60 = approx. 145 ml/min

That seems pretty fast to me. Am I overlooking anything or should it really be opened up that fast?

I guess that's only about 6 seconds to fill a 15ml measuring spoon. A little more than twice what I run my calcium reactors at (I run mine at 60ml/min) so I guess it's maybe not that far off. Hmmm ... interesting.

Ok so the real question is how much time do I give myself to open up the reactor to that speed?

Arggh math! My eyes!!!!! :razz:

I say damn the torpedoes! Full speed ahead!

Seriously though, that seems pretty fast, why not just try a fast drip for now, then ramp it up from there?

I don't think you want to be increasing your drip rate...

You want a slow drip rate until you have enough bacteria to use up all the nitrate at that rate. Then you start increasing your drip rate slowly until you find the right rate for your current bioload. As your nitrate in the tank comes down you will further increase your drip rate until it is balanced at Zero nitrate in the tank, and zero coming from the reactor.

2 weeks is too early to be jumping to conclusions and changing operation of your setup..

Be nice now. I'm not jumping to conclusions but I am questioning whether I should wait to see this thing help sort out an immediate situation I have right now.

3 months from now is practically March and that's a long way's away. Many things can happen in that timeframe.

As far as increasing the drip rate, I haven't. It doesn't make sense to me to start that until I see a NO3 reading on the output that's less than the input, because until then, there obviously isn't enough colonization to make the difference.