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Unread 11/11/2012, 03:00 PM   #9
JohnV8r
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Join Date: Oct 2011
Location: El Dorado Hills, CA
Posts: 399
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.



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.


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Current Tank Info: 175g reef (48"L x 28"D x 30"H), 15g Refugium, 30g Sump w/ASM G3 (gate, mesh, & recirc mods), 10K GPH flow via 3 Tunze 7096 + return, ATO via Tunze Osmolater, 2x250W Radiums, GFO, Carbon, dosing vinegar/vodka, Alk, Ca, via 3 BRS dosers & Apex.

Last edited by JohnV8r; 11/11/2012 at 03:11 PM.
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