View Full Version : Sulfur denitrator question

02/28/2011, 11:22 PM

I have a recirculating sulfur denitrator that I am having some trouble with. I have several friends that have units quite a bit smaller than mine that are able to get a pretty good stream of nitrate free effluent out of the reactors after they have cycled. I have a unit that is aprox 8" diameter tube x 24" tall with a gallon of caribsea live sulfur media and some large calcium media on top of it. It recirculates with a maxijet 600 pump and is gravity fed from the tank in the room above the sump where the reactor sits. The reactor is running on a approx 500 gallon system with about 15ppm nitrate and very little phosphate (maybe 0.01-.02 measured with a hanna)

The problem with mine is that it has been running since September and I am still only able to get to 2-3 drops or so a second before the reactor is unable to keep up and allows nitrate to pass through. At first I thought that I just hadn't waited enough time for bacteria to build up but I have left it for over a month at a higher flow rate, maybe 4 drops/sec, but it still has nitrate left in the effluent albeit lower than the main tank.

I recently went to a friends house who is running the medium size korallin unit on is 350-400 gallon system and he has a steady stream of effluent coming out of the reactor with absolutely 0 nitrate... he even has to keep turning it up so he doesn't produce sulfuric acid. His yellow sulfur media has turned VERY dark w/ black patches everywhere. My sulfur looks relatively new still?

Any ideas what I need to do to get this thing running more efficiently? My initial thought is to add more sulfur but i'm not sure if the sulfur media is the what is limiting bacterial growth? All of the online articles I have read state that the almost 4 liters of media should be able to handle this much volume.

Any ideas on where to go next?

On a side note, I started carbon dosing (8 parts vinegar to 1 part vodka) about 2 months ago to see if I could bring the nitrates down. I have gradually increased to 200ml daily dosed with a litermeter pump (doses 150 times per day in very small increments). If I get over the 200ml mark I get a noted bacterial bloom that will/can be removed with heavy skimming (super reef octopus 5000 external skimmer) after only about 8 hours of ceasing dosing. I haven't seen my nitrates move a bit since I started dosing! I expected to see a marked decrease after the bacterial blooms but the tank is sitting at a constant 15 or so ppm.

Second side note... I also run a liter of BRS biopellets in a reactor that feeds into my skimmer (started in October but haven't noticed any improvement with them either, hence the liquid carbon dosing started in January)

And before anyone says bad test kit... I am using the lamotte low range kit and it is able to accurately read the nitrate reactor as having little to no nitrate when the effluent is turned way down (1-2 drops/sec)

02/28/2011, 11:58 PM
Back off on that Moon Shine there partner. Those big burly bacteria are competing for oxygen in your tank with the other critters.

Just adjust your unit for a slow flow and wait --- it will kick in if the oxygen content in the media is low enough.

03/01/2011, 04:18 AM
Well, you are doing too many things at the same time. You will have to decide what method you prefer: vodka addition or sulfur denitrator. I preferred the second and kept the first for myself :lmao:

I run a SD for almost a year. I've learned many things.
First and the most important; sulfur pellets can feed the bacterial population, but have poor properties (specific surface) to colonize. I have 2L of Seachem matrix inside mine as support for bacterial growth.
Second; You will need about 1/3 of total recommended sulfur since this will be used as food rather than substrate. Add some every 6 months but not much.
Third; get a dedicated feed. Gravity feed is prone to air mix ingestion (oxygen addition) and it makes SD difficult to control. Remember that it works well when there is no oxygen inside (anaerobe conditions).
Forth; get an ORP reader capable to read negative values. This is the best method to control.

hope it helps,

03/02/2011, 06:04 AM
I agree that the reactor might need more media. You could give it a shot. I don't understand yet why using both the reactor and dosing vodka should be a problem. That seems a reasonable option to consider. I suppose it's possible that the alcohol might interfere with the denitrator in some way, but I'm not sure how.

03/02/2011, 03:12 PM
I agree that the sulfur reactor and the vodka/vinegar shouldn't be a problem together...the more bacteria to uptake the nutrients the better right? I think I'll try to add some more media as well as add some porus media like the seachem matrix and try to get it to cycle through.

03/02/2011, 05:59 PM

a well tuned Sulfur denitrator will supersede in terms of Nitrate removal effectiveness any kind of chemical addition (my observation). To me the fact that Mike decided to go in parallel for vodka addition is a sign that, to some extent, his Sulfur denitrator was not tuned properly.
As I said in my previous post, I run one for almost a year and I do water changes just to replenish the trace elements. Tank Nitrates are undetectable by an Elos kit regardless the frequency of water changes and I do have a very heavy bio-load for a 60g cube.

The only serious watch out with Sulfur Denitrators is their negative influence on Alk. I dose Ca once a day and Alk twice (Randy's recipe).

hope it helps,

03/02/2011, 10:19 PM
So what do you suppose is leading to my reactor not being tuned? I have followed all of the guidlines about starting with only 1 drop per second/ test effluent after a few days to a week/ increase effluent rate/ test again in a week.... Every time I get up to about 3-4 drops/second it never cycles fully through to 0 nitrate, even after waiting several weeks...

03/02/2011, 10:44 PM
I would definitely heed MaLi's advice about ditching the gravity feed. Any air allowed to mix will negate the oxygen-depleted environment needed for its successful operation. Another note, IF you are measuring ANY nitrite, your Lamotte nitrate test kit will show a positive. I learned this from Randy Holmes Farley. So, get a nitrite test kit and see if you have nitrite in your effluent.

These things are a bit tempermental, but here is what I would do to get yours going again. First, I would remove the aragonite from the chamber and just use the sulphur pearls. Second, I would beef up the recirculating pump to something pressure rated, perhaps a small Mag 5 or Iwaki 15 or 20. After you get a slightly stronger pump, I would add some of the sulphur beads/pearls from Premium Aquatics. They tend to let water circulate through them better than the flakier sulphur.

Since things aren't working right now, it won't hurt to revamp things and start from scratch. Start it at a drip per second and measure nitrite. Once nitrite is gone, you can measure for nitrate. When you have NO nitrate, you can increase the rate of the flow. Just go slow with it.

I've had my share of issues and I think I can overcome these dang things finally. I have zero nitrate in my system and have to turn it up to keep a happy medium. It sounds like your friend's reactor is going the wrong way and that is why his media is turning black...hydrogen sulfide. He might want to take it offline and reduce the amount of media.

03/04/2011, 03:32 PM
Is there any truth to the rumor that the sulfur bacteria prefer higher (80 to 90 degrees F) to perform optimally? We added a heating pad on low wrapped around the unit and have had much better luck. We run the house at about 70 and do the drip feed through a 50 foot clear coil to allow for bacteria to work on the oxygen before it hits the reactor causing the tank water to drop to ambient house temp. Also we have the aragonite media above the sulfur in the same unit (Midwest Aquatics I notice they went under). Woudn't it be preferable to run a separate unit for this media to maintain a lower Ph for the sulfur bacteria. I notice the higher end units are set up this way.

03/04/2011, 03:37 PM
Hmmm... I do run my tank much cooler than alot of people do, in the 75-76 degree range. the reactor sits in my garage that stays pretty cool.

03/10/2011, 09:40 PM
The tank (the 125) is down from 40 to about 4or 5. It took about 3 weeks but once it got lined out it was smooth sailing. When they are working in my opinion there is nothing better. I might rig one up for the 58 but it is LPS and not as critical for low nitrate.

03/11/2011, 04:15 AM
The tank (the 125) is down from 40 to about 4or 5. It took about 3 weeks but once it got lined out it was smooth sailing. When they are working in my opinion there is nothing better. I might rig one up for the 58 but it is LPS and not as critical for low nitrate.

ha, ha ... like to say it " I told you so !" :p


03/11/2011, 09:00 AM
I used a diy sufur reactor alongside start up vodka dosing and it worked well.5 weeks to 0 nitrates from 80 plus ppm on a 550 g system. I did use a small power head on the feed line to boost the gravity feed.

Once the nitrates dropped the reactor produced hydrogen sulfide. Reducing flow and media to retune to lower nitrate levels should help this but I lost patience with it ;the vodka took over nitrate reduction tasks and has been doing very well without the sulfur reactor for over two years .

03/11/2011, 09:03 AM
TMZ, how long did your sulfur reactor run till you had sulfide production? Same media bed?

03/11/2011, 09:55 AM
The hydrogen sulfide started about a week after the tank nitrate reached a 0 reading on the api test. I did have some seachem matrix media mixed with the sulfur which may have contributed to it since it has many pores where anoxic conditions could persist perhaps more than on the pellet surfaces. Could be some of the low dose vodka got in there too. I removed it and tried new media, by half and it happened again after a week or so even with the reactor effluent t at max. I took it off line to modify it to allow greater effluent flow but never got back to it since the vodka/vinegar dosing was doing the job.

03/11/2011, 09:56 AM
BTW, running the effluent through some gfo can accelerate the hydrogen sulfide oxidation detox process.

03/11/2011, 12:17 PM
the vodka took over nitrate reduction tasks and has been doing very well without the sulfur reactor for over two years

I think this is where my system might settle out. For the first time in months the nitrate is down below 10ppm. I might just end up scrapping the sulfur and using the vinegar/vodka as it seems to be doing the job.