Denitrification Reactors vs Vodka Dosing
 

I have a quick question about using denitrification reactors versus vodka dosing an entire system.

I currently vodka dose 3.3 ml per day via a doser that delivers .825 ml every six hours.

Throughout my vodka dosing experience I have learned little nuances like where in your system you dose impacts potential cyano outbreaks and dosing via a doser vs single dosing by hand allows better control of the overall result.

I have always wondered what impact vodka dosing may or may not actually be having on coral coloration. For example, most of my chalices turn purple (e.g. when I put green mummy eye chalices in my tank, they will turn purple with peach to red colored eyes). I also have some of the proverbial burned tips on my acros.

I recently saw a video of a DelTec Denitrication Reactor that was using vodka as it's food source for the bacteria colonies in the reactor. That prompted these questions:

1. Is a denitrification reactor that uses vodka as its food source a suitable way to contain any potential side effects from vodka dosing an entire display tank?

2. Would you lose the beneficial impact on phosphates that vodka dosing an entire system has if you limited the introduction of vodka to a denitrification reactor? It is my understanding that some phosphates bind with certain materials...does that mean you have to take the phosphate eating bacteria to the phosphate or would vodka dosing a denitrication reactor simply concentrate the benefit in the reactor the same way a GFO reactor does?

Thanks in advance.

Great question about the PO4 impact. Looking forward to seeing some replies.

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I haven't seen that product. Can you provide a link? The only product my search turns up is a sulfur reactor.

I am thinking he is talking about the deltec nfp509 reactor

Jonathan,

Here is the video that discusses the DelTec Denitrator. Check at about 3:28 on the video for the denitrator discussion.

http://www.youtube.com/watch?v=aXSL0MZAdiM

The thing that caught my eye is that the vodka is dosed into the denitrator instead of the entire system. I can't help but wonder if that doesn't keep any of the potential negative side effects of vodka dosing contained in the denitrator much in the same way that Randy told me dosing into my overflow would move the biological process from vodka dosing "upstream" of my display tank. Since the denitrator has a very slow intake, it would seem logical that the biological process from introducing vodka might be entirely contained in the denitrator, thereby providing the benefit of vodka dosing while reducing the likelihood of potential negative side effects.

As many things in this hobby can be counterintuitive, I was just looking for some feedback to see if the prevailing thought was that a denitrator would contain the biological process from vodka dosing.

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Sorry, I've been busy. I'll take a look at the video if I have some time later on. I'm not sure anoxic the reactor might get, and what the goal of the carbon source is. Personally, I'd just stick with regular vinegar or vodka dosing to limit complexity. Whether the side effects would be better or worse might vary from tank to tank. I would be cautious about assuming that the denitrator is safer. Denitrator coils, which probably operate similarly, can be touchy, for example.

Jonathan,

IME carbon dosing has been second only to live rock in what has advanced my enjoyment of this hobby in the 25 years I have been involved.

I began vodka dosing a little over a year ago in an attempt to better control my nitrates and phosphates. I have been AMAZED at the results. At 3.3 ml of vodka per day now dosed with dosers at .825 ml every six hours, I have nitrates per my Elos test kit of 1 or <1. I have had very few regular negative side effects, EXCEPT ONE. Swings in alkalinity have created burnt tips or RTN'd some of my more sensitive SPS corals. I attribute the burnt tips or RTN'd corals to sensitivity to alkalinity changes that are amplified by vodka dosing.

I dose kalk in my ATO.

Living in the Sacramento metropolitan area means I generally have less humidity than in the Bay Area, but the humidity is relatively stable. I don't use a chiller. Instead, I have my Apex Controller set up to turn on a group of computer fans mounted in my display top that blow air across the top of my display tank when my system temperature goes above 78.5. I fight my metal halide lights daily to control temperature. Generally, my temp swings from 78.0 to 80.0 daily. On the off occasion that my system temp goes above 81.0 degrees, my Apex turns my lights off.

Where I think I run into trouble is when either the humidity goes lower than usual (North wind) or the ambient temperature in my house goes up and I end up evaporating more than my average 2 or so gallons a day. That means I end up putting more kalk in my tank and my alkalinity can creep up over 8.0 dkH. I try to keep my dkH at 8.0 or below all the time now since learning that dkH above 8.0 while dosing vodka can cause burnt tips in SPS corals. My recorded chemistry over the last year is as follows:

Date NO3 Ca dKH Phos PH Mg
10/22/2011 2.5 550 10 0.5 8.3 1250
10/24/2011 1 550 10 0 8.3 1400
10/28/2011 2.5 550 9 0 8.3 1300
11/1/2011 10 500 8 0.5 8.3 1450
11/4/2011 10 550 8 0.5 8.3 1550
11/16/2011 0 500 7 0 8.3 1350
12/3/2011 0 450 10.5 0 8.3 1250
12/18/2011 0 450 9.5 0 8.3 1450
12/30/2011 0 500 9 0 8.3 1400
2/6/2012 0 450 7.5 0 8.3 1550
2/25/2012 0 450 9 0 8.3 1450
3/17/2012 0 500 10 0 8.1 1450
4/25/2012 0 450 8 0 8.3 1500
7/9/2012 1 450 8 0 8.3 1450
8/16/2012 1 400 7.5 0 8.1 1550
10/10/2012 1 400 8.5 0.04 8.1 1575
11/7/2012 1 400 8.5 0.07 8.2 1700

There are no recorded readings from September 2012 because that is when I had the powerhead blow my sand bed all over and create chemistry issues. Clearly the most volitile area of my reef chemistry is my alkalinity.

Additionally, my Ca is becoming harder to maintain with kalk alone. I have considered using vinegar to super saturate my kalk, but have been concerned that will likely make the alkalinity more difficult to maintain at 7.0 - 8.0.

So factoring the totality of the circumstances in my reef system (mostly my inability to consistently maintain stable alkalinity at 7.5-8.0 and the knowledge that I will need more Ca soon) and that my objective is low nitrates without burnt SPS tips, I began trying to figure out ways to reduce my dependence on vodka dosing to maintain low nitrates. That led me to essentially three reasonable conclusions:

1. More skimming/less vodka dosing,

2. Biopellets

3. An alternative nitrate reduction methodology.

I have used a modified ASM G3 skimmer since 2007 that has always done a solid job for me. That skimmer unmodified is stated to be for systems up to 250 gallons. I am just under 200 for a total system. My "more skimming/less vodka" solution was to replace my sump and ASM G3 with a sump and external skimmer like a SKIMZ SM 202 or DelTec TC 2060 External.

Here is a very old photo that shows my current sump/skimmer/refugium layout.

http://www.reefcentral.com/forums/pi...ictureid=36586

By getting a different sump with a refugium, I could move my external refugium out and put a larger external skimmer where the refugium is now. My current refugium receives input from a "T" and gate valve in the return line. By putting the refugium as an integral part of the sump, I would then be sending all flow through the chaeto in my refugium. Additionally, I was hoping a skimmer rated for 450+ gallons would allow me to "overskim" my system and achieve the same nitrate levels without the vodka.

I didn't really like the inability to control biopellets, so I eliminated that as an option.

Then I saw the video with the DelTec Nitrate Reductor. Looking at the system, the vodka is 1) dosed into the reactor, giving the ability to precisely control how much vodka is dosed, 2) the flow through the reactor is controlled by a drip counter meaning flow through the reactor is very slow (making me wonder if the biological process was able to be contained in the reactor), and 3) the flow through the reactor is controllable. A bonus with the DelTec Reductor was that an ORP probe and a solenoid could allow for the complete automation of the biological process in the reactor.

So there is the reason I have asked about Nitrate Reactors vs Vodka dosing. My objective is to determine if there is a reasonable alternative to vodka dosing that would allow me to be as successful in removing nitrates from my system as vodka dosing has.

I also understand that I would likely be able to stabilize my alkalinity swings by moving to two part dosing alk & Ca. That may be a necessary change at this point regardless of whether I can eliminate my dependence on vodka dosing.

Let me know if you have any questions.

I look forward to hearing your thoughts.

Thanks in advance.

I have a Deltec Vodka based Nitrate reactor there can be negative impacts on your tank I will try to post a picture of the bacterial blum I got from mine. I would suggest using a dosing pump that is easy to use so you can change easily. One of the difficulties is getting a pump that doses 32ml/min for my unit and 50ml/min for the one shown, I did my both of my peri pumps from deltec but the 32 ml pump failed instantly and was never resolved.

I don't see a connection between vinegar dosing and unstable alkalinity. I suspect that the variable evaporation rate is more important there.

Although the vodka most likely is contained in the nitrate reactor, I'm not sure why that should necessarily reduce the side effects. That would depend on what's causing the side effects, and we don't have an answer to that question.

Rather than pay for the reactor, I'd try a denitrator coil, possibly DIY, first. The risk level likely is lower, and it'd be simpler. Either of those approaches will have some risk.

Absolutely, the alkalinity issue is caused by the variable evaporation rates. I didn't mean to suggest that vodka dosing was causing unstable alkalinity.

However, based on what I've read, I am getting burnt tips and occasionally RTN'ing some of my SPS corals when my alkalinity goes above 8.0 dkH BECAUSE I am vodka dosing. I'm reading that if I were not vodka dosing, I would not suffer burnt tips/RTN when my alkalinity crept up above 8.0 dkH. That is why I was hoping the nitrate reductor would contain the effects of vodka dosing in the reactor itself.

I'll check out denitrator coils.

Is there any reason you can't maintain Alk at or below 8?

I think the problem is that I am dosing kalk through my ATO. When it is either warmer than usual or less humid than usual, I end up dosing more kalk through my ATO due to higher than normal evaporation.

Additionally, I believe the Seachem Reef Salt that I use has a dkH of 10. When you throw in weekly water changes with the kalk that is added, it has been difficult to keep my alkalinity between 7.0-8.0.

If you look at my dkH readings in the post above, you will see there have been only three occasions in the last 13 months where my alkalinity has been below 8.0.

Ethanol is miscible. it will diffuse in the water readily. Perhaps more bacterial activity will occur in a reactor and less in the tank; perhaps not. The bacterial involved are mostly benthic ;so, they colonize surface areas. They consume some nitrate for food and some in anearobic activity. They also consume organic carbon and PO4 for phospho lipids , no matter where they grow. For me dosing 1/2 upstream from a can full of live rock serving as a cryptic refugium and the rest into a high flow area of the sump works well to limit unwanted stringy bacteial mass in the display tanks.

Steady alkanity is important ,ime. Swings even within acceptable ranges seem to occasion stn. FWI I've been dosing vodka and vinegar for 4 years with alk very constant in teh 8.9 to 9.6 range without stn and with good color and growth.

Tom,

Thanks for that.

I think based on all the feedback I have received the bigger issue here for me is the lack of precise control of alkalinity as a result of using kalkwasser in my ATO. Your experience with no RTN or burnt tips on SPS with an alkalinity of 8.9 - 9.6 leads me to believe that I may be able to achieve my goals by using a more traditional 2-part dosing regimen of alk, Ca, and Mg that would allow me to tighten up the alkalinity variations. That certainly would be the most cost effective next step.

Also, I may build a denitrator coil as that seems like a simple DIY project that I was unaware of until Jonathan's suggestion prompted me to Google it.

Thanks for your input.

Well, I use kalk but not in an ato. I dose from a still reservoir 24/7 at preset dose which appoximates daily top off needs and is is broken up into 150 small increments throughout the day.

The thing about the coil is that it is designed to establish a low oxygen environment which encourages bacteria to use NO3 for oxygen.. In the presence of organic carbon like vinegar or vodka,etc, the bacterial activity could easily create anoxia, no oxygen/no nitrate, which leads to sulfate reducing bacteria taking over . That process produces elemental sulfur, sulfides and toxic hydrogen sulfide gas ; so, if you use one, monitor it closely.