View Full Version : Downside risks of Sulfur Denitrator
serpentman
10/06/2009, 09:44 PM
I am considering using a sulfur denitrator to keep my nitrates in check. However, I wanted to better understand any potential risks involved. Any thoughts?
Billybeau1
10/06/2009, 11:25 PM
I've never used one so I'm not much of an expert on that. Have you exhausted all other nitrate reduction options ?
Haksar
10/07/2009, 04:58 AM
Low ph/alk due to sulfur will be an issue.
serpentman
10/07/2009, 06:18 AM
I am currently considering other options as well. I am doing 10% PWC every week at the moment. I am not running a fuge so may incorporate one if I can find a good place to plumb it in.
Unfortunately I travel too much for work to be able to dose vodka, etc. or I would probably explore that option.
Current nitrate levels appear to be 2.5ppm, which I believe is ideal for SPS. However, I am concerned that it may go up so want to have a plan in place if I start to trend in that direction.
arredondojason
10/07/2009, 11:44 AM
look into a coil denitrator a lot less maintenance and easy to build.
BradR
10/07/2009, 02:02 PM
At the mid west site they say their sulfur denitrator increases ca and alk?
Okayamapiper
10/08/2009, 02:50 AM
Increasing Alk and pH would require a huge buffering column. The sulfur using bacteria require low oxygen, so a slow flow rate is necessary, but too slow and the denitrator goes anaerobic and will smell like rotten eggs and not work properly. Too fast and you dump low pH into the sump, consuming Alk and lowering pH.
The ratio is 1:3 for sulfur:aragonite. The sulfur should be about 1% of the water volume. You need to play with the flow rate so that you get zero nitrate and nitrite. Too fast and the bacteria cannot strip all of the oxygen from the nitrate creating deadly nitrite. Too slow and you get hydrogen sulfide, poisoning your tank as well. Once set up they work great though.
A coil denitrator is less dangerous but requires a carbon source to feed the bacteria. Dosing vodka or sugar is common.
I've used a coil denitrator with sulfur and aragonite, but since I made my second column too small I lack buffer and the effluent is pH 8 with the main tank at 8.2, it is robbing my tank of Alk to try to reach equilibrium. Now I dose Kalk in the denitrator effluent to correct this problem. Once I get time, I will make a bigger second column.
Sulfur require a little more care in set up but long term they are less work as the bacteria needs no external food source.
Randy Holmes-Farley
10/08/2009, 05:34 AM
The ratio is 1:3 for sulfur:aragonite.
Why do you say that?
Assuming one wants to use aragonite (an imperfect solution, IMO, but maybe useful), wouldn't it depend critically on the surface area of each?
BradR
10/08/2009, 06:41 PM
I just found it very interesting that guys w/ 5000+ posts are switching from bacteria driven systems to denitrator equipment...
Randy Holmes-Farley
10/09/2009, 04:38 AM
Tank treatments come and go, and sulfur denitrators are currently chic to many. :D
Mr Reefer 1690
10/09/2009, 05:30 AM
I've had a coil denitrator running on a F/O tank for years. It maintains the nitrates at 0. I've never fed it anything, all you need is a slow drip thru it.
Is there anything in the effluent that could affect water chemistry or harm corals?
I'm curious as to why more people don't run them on reef tanks?
Randy Holmes-Farley
10/09/2009, 05:55 AM
Most people who have used them find them tricky to run long term. Too fast of flow accomplishes nothing. Too slow risks delivering toxic hydrogen sulfide to the tank.
Most coil denitrators use an organic carbon source of some sort (methanol or maybe a solid material). You add nothing to it? Maybe you just have farily high organic levels in the water.
I discuss them a bit here:
Nitrate in the Reef Aquarium
http://www.advancedaquarist.com/issues/august2003/chem.htm
serpentman
10/09/2009, 06:43 AM
Personally, I travel a lot for work which means I am gone for at least 3 days at a time so dosing carbon isn't a good option. I am trying to find a reasonably automated system. Granted they have to be tweaked, I figured "tuning" a denitrifier would probably be akin to a Ca Reactor.
I have run a fuge in the past with great success. However, I have had several occasions where chaeto simply falls apart and dies. I don't want to use caulerpa because I don't wish to light it 24/7.
serpentman
10/09/2009, 06:44 AM
Personally, I travel a lot for work which means I am gone for at least 3 days at a time so dosing carbon isn't a good option. I am trying to find a reasonably automated system. Granted they have to be tweaked, I figured "tuning" a denitrifier would probably be akin to a Ca Reactor.
I have run a fuge in the past with great success. However, I have had several occasions where chaeto simply falls apart and dies. I don't want to use caulerpa because I don't wish to light it 24/7.
Randy Holmes-Farley
10/09/2009, 07:06 AM
Granted they have to be tweaked, I figured "tuning" a denitrifier would probably be akin to a Ca Reactor.
Coil denitrators have traditionally been much less "set and forget" than are CaCO3/CO2 reactors. Sulfur denitrators have been used for a shorter period of time, but they may be more forgiving.
serpentman
10/09/2009, 07:13 AM
That's definitely the way I am leaning. In addition, I think I would need a mile of coiled tubing to address my volume.
Rocco8
10/09/2009, 08:15 AM
I am using aquaripure with great success. You must inject vodka (ethanol) once a week.
See http://www.aquaripure.com It is a denitrater that converts nitrates and ethanol to Carbon dioxide and nitrogen. Not a sulfur denitrater with alk and pH issues.
Randy I never heard of anyone injecting methanol which as you know is very toxic to humans in an aquarium.
Randy Holmes-Farley
10/09/2009, 09:07 AM
Randy I never heard of anyone injecting methanol which as you know is very toxic to humans in an aquarium.
Methanol was a pretty common carbon source for coil denitrators. It is not added directly to the tank, just the coil. :)
But many other solids and liquids have been used.
Mr Reefer 1690
10/09/2009, 10:19 AM
Randy
The denitrator has been running for 5+ years. I've never added anything to "feed it". Drip rate is maintained around 1 drop /sec.
It took around 5-6 weeks of operation before I noticed any decrease in nitrates. But they've been 0 ever since the unit cycled.
I've never been able to find a good article on coil denitrators
thanks
I have used the diy sulfur denitrator several times.. It's very good for reducing high nitrates in a relatively short time , in my experience . However, it's not set and forget. Establishing a flow rate for effluent with a reduced NO3 output without hydrogen sulfide is tedious and requires frequent monitoring and adjustment . Once it gets going and nitrates drop to near zero it will go to hydrogen sulfide very quickly even at full flow, i.e.,about 5x the amount of sulfur per hour. So I intend to use it only in high nitrate situations for a short period of time. Running a course of aragonite won't produce much additional alkalinity or calcium. Hardly worth the effort . I tried it and still needed to dose some baking soda. Randy did a summary on this minimal effect.
I dose vodka and vinegar mixed in my lime water(kalkwasser) for top off via a dosing pump enabling dosing the reservoir once a week or so instead of the tank daily.As I understand it the ethanol is miscible insuring an even distribution and the high alkalinity in the lime water prevents bacterial consumption of the ethanol or acetic acid in the reservoir.
NexDog
10/10/2009, 08:27 AM
I've had a midwest unit running for 3 years now. It was running great, I played with it and now I can't get it dialled in correctly and have to bleed out air almost daily. It never got my nitrates to zero but it helped a lot. Nitrates currentlt at 4, maybe due to the reactor not being efficient. Also the media is black - does it need to be changed out?
I'm currently trying vodka. Am up to 6ml per day. No nitrate decrease yet but I'm finding I have to clean the front more often.
I would guess the black stuff could be sulfides and would clean it out. Do you get a sewer gas smell when you bleed it?
NexDog
10/10/2009, 06:55 PM
Yah, smells like rotten eggs.
Randy Holmes-Farley
10/11/2009, 09:11 AM
The denitrator has been running for 5+ years. I've never added anything to "feed it".
And this is a carbon denitrator, right, with no sulfur in it? Odd that you add nothing. That is not the normal use.
Young Frankenstein
10/11/2009, 09:43 AM
I agree with Randy (always :) ) and Mr Reefer, I did a DIY denitrator and is set and forget basically, happy with it.
Maybe some day bio balls will come into play again, in a different way :)
Its a 18 gal bio blalls denitrator with a filter in front feeding it, its the box with the flowers on top, it runs normal now for about 1 month or 2 with ORP swings from +60 to -250 at one time it reched a -600mv
http://i497.photobucket.com/albums/rr339/frankensteinsk/DSCN2328.jpg
http://i497.photobucket.com/albums/rr339/frankensteinsk/DSCN2324.jpg
http://i497.photobucket.com/albums/rr339/frankensteinsk/DSCN2329.jpg
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