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Old 12/04/2017, 08:04 AM   #1
EnderG60
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Vodka dosing and alkalinity questions

So I started Vodka dosing in an effort to reduce my phosphates without needing so much GFO.

I remember reading that alkalinity over 9 was not recommended as people were seeing SPS with burned tips.

Prior to vodka I had always kept my alk pretty high (in the 10-12 range) since my LPS seemed to like it and the SPS didnt mind. When I tried to do the same while dosing vodka I started seeing some burned tips and tissue loss.

So why the difference with the vodka?


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Old 12/04/2017, 08:19 PM   #2
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No one has any particularly credible theory as to what's happening. Some people think that the faster growth is causing some sort of problem, as higher alkalinity makes calcification easier. I think I remember other theories as well, but I don't think any of them have much in the way of data to support them.


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Old 12/05/2017, 12:00 PM   #3
EnderG60
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I have heard of regular SPS tanks having that issue, but Im more curious why I only started having the issue when I began vodka dosing.


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Old 12/05/2017, 12:15 PM   #4
tmz
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Hard to say. Vodka is ethanol and water. The ethanol goes to acetate which feeds heterotrophic bacteria that use it as a carbon source ;they also deplete other elements particularly PO4 and NO3. Both are used by corals in their growth process including their control of the growth of the skeletal matrix ; depleting them requires the coral to adjust. If deficiencies in nitrogen or phosphate occur it can throw the balance for controlled growth off; more so it seems when higher alk encourages faster calcification.

FWIW I have been dosing vodka and vinegar for over 8 years in a a heavily fed mixed reef system with a majority of sps. PO4 holds between .02 to .04 ppm with NO3 under 1ppm. alk in the 8 to 10 dkh range doesn't occasion burnt tips or other stn in my case.

Once in a while a very small of sodium nitrate offsets any potential nitrogen deficiency.


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Old 12/05/2017, 12:20 PM   #5
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Quote:
Originally Posted by EnderG60 View Post
I have heard of regular SPS tanks having that issue, but Im more curious why I only started having the issue when I began vodka dosing.
It just seems that with lower nutrient levels corals cannot "adapt (or tolerate)" to the higher alkalinity levels..

Now you didn't mention any specific nutrient levels of neither nitrates nor phosphates but I'd bet that the vodka is causing your nutrient levels to be lower (as it should) thus the corals cannot tolerate the higher alk without getting burnt..

I'm sure there is likely a scientific answer where one plots zooxanthellae growth rates against coral calcification rates and shows an imbalance that forms in your situation and thus the zoox cannot keep up with calcification or whatever..


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Old 12/05/2017, 07:36 PM   #6
JustAClownFish
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Quote:
Originally Posted by EnderG60 View Post
So I started Vodka dosing in an effort to reduce my phosphates without needing so much GFO.

I remember reading that alkalinity over 9 was not recommended as people were seeing SPS with burned tips.

Prior to vodka I had always kept my alk pretty high (in the 10-12 range) since my LPS seemed to like it and the SPS didnt mind. When I tried to do the same while dosing vodka I started seeing some burned tips and tissue loss.

So why the difference with the vodka?

Do you know why you're seeing burned tips with higher alk? When you dose vodka you reduce nutrients such as phosphate, which is known to inhibit calcification, so your SPS can take up more alk/ca, thus grow faster. In other words, the skeleton outgrows the soft tissue. It's just a cosmetic thing. If you don't like it keep your alk at a NSW level of 7dkh.


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Old 12/05/2017, 10:46 PM   #7
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Keep your alk at 7-8dkh when dosing vodak or you will burn your sps. I did vodka for a while and it does work but bio pellets are easier and more forgiving ime.


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Old 12/05/2017, 11:48 PM   #8
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Originally Posted by JustAClownFish View Post
Do you know why you're seeing burned tips with higher alk? When you dose vodka you reduce nutrients such as phosphate, which is known to inhibit calcification, so your SPS can take up more alk/ca, thus grow faster. In other words, the skeleton outgrows the soft tissue. It's just a cosmetic thing. If you don't like it keep your alk at a NSW level of 7dkh.
Will increased food for the reef and fish help the soft tissue "keep up"


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Old 12/06/2017, 08:50 AM   #9
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Dosing carbohydrates produces protein, biomass. A part of this protein will be removed by a skimmer ( max +- 30%, http://www.baharini.eu/baharini/doku...iwitafschuimer ) most of it will be consumed by other organisms and become part of the food chain. Consumption is formation of biomass and ammonia. This ammonia will be nitrified to nitrate. Nitrification does consume alkalinity. To remove the nitrate produced carbohydrates must be dosed. A cycle is introduced from NO3 to NO3 , this cycle includes nitrification consuming alk.

At a high C:N ratio ( biopellets reactor?) no nitrate is formed as ammonia will be assimilated to produce protein. The assimilation of ammonia NH4 consumes alkalinity but only +- half of alk consumption if the same amount of ammonia was nitrified. At the downsite the very high biomass production which is +- 40 x the amount produced during nitrification of the same amount of ammonia. The cycle introduced this way is from NH4 to NH4. including the formation of a lot of biomass.
What to do with the produced biomass?
Carbon dosing is common practice in aquaculture systems. In these systems the biomass will be harvested after a period of time.


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Old 12/06/2017, 12:52 PM   #10
EnderG60
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Originally Posted by JustAClownFish View Post
Do you know why you're seeing burned tips with higher alk? When you dose vodka you reduce nutrients such as phosphate, which is known to inhibit calcification, so your SPS can take up more alk/ca, thus grow faster. In other words, the skeleton outgrows the soft tissue. It's just a cosmetic thing. If you don't like it keep your alk at a NSW level of 7dkh.
Exactly what I was asking about, thanks!

Im finding the new balance of parameters with the vodka dosing now. My original goal was to reduce my phosphate to inhibit the algea growth. I started with my nitrates at 2-4, and phosphate at 0.3-1.2. I got to a point where my nitrates zeroed out and my phosphate was still in the 0.3-0.5 range, so I started dosing sodium nitrate.

Im now holding steady with nitrates of 2-4, and phosphate of 0.01-0.03, while dosing a 450g system with 21 ml a day of vodka which I think should be a good happy spot for a mixed reef.

So now I just need to find a new dosing balance now that I have the vodka dosing figured out. My alk intake has gone up quite a bit but never seems to go above 8. If I dose it manually it jumps for a day, I get burned tips and then its back down to 8.

I just want to make sure I understand whats happening so I dont start chasing old numbers that wont work anymore.


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Old 12/06/2017, 01:28 PM   #11
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To be very precise, the skeleton can't outgrow all the tissue of the coral, because the tissue forms the skeleton:

http://www.advancedaquarist.com/2002/4/chemistry

The "burnt tips" might be places where the tissue is very thin, in some cases, at least. Other people seem to see tissue recession and similar signs of poor coral health.


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Old 12/06/2017, 08:17 PM   #12
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Will increased food for the reef and fish help the soft tissue "keep up"
If your no3 and po4 is super low yes it will. Corals need light and food for their photosynthetic algae to thrive, a major nutrient source for algae is nitrogen and phosphate. You want to keep levels low but detectable. If you system already has controlled low nutrients carbon dosing will not help any and can cause major issues.


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Old 12/07/2017, 04:35 PM   #13
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Ok part 2. Why has the vodka dosing caused my alk dosing to nearly double?


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Old 12/07/2017, 05:45 PM   #14
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I nature corals grow in very low soluble nitrate and phosphate levels (almost in trace amounts) and the alkalinity of natural sea water is around 7.5dKH.

In a tank if you try to replicate the low nutrient levels (through carbon dosing and subsequent consumption of nitrate and phosphate), you need to lower alk as well.

The reason for this is not very clear. But from a very simplistic point of view. corals need Ca and Alk to built their skeletons. More alk allows more skeleton to be built. But this also requires the coral soft tissue to grow larger and produce more calcium carbonate. So in higher alk coral cells themselves need more phosphate and nitrate to grow and built CaCO3 skeleton, but they also need N and P to feed their symbiotic algae. And in lower alk, the case is the opposite.

Phosphate is also known to be a substrate that protects corals from bleaching. Now its important to consider that whitening happens first around the tips, than the parts of the coral that receive more light and eventually the whole coral will turn pale.

Tips of the corals normally receive the most light and they are the parts that grow the most. So I think what happening is a nutrient imbalance between the symbiotic algae and the coral cells. Corals and zooxanthellae form a synbiotic relationship where corals provide the nitrate and phosphate and in turn algae share some of the carbon dioxide it fixes into organic compounds with the coral. When you have high alk but low N and P, it creates a large nutrient imbalance around the tips. When N and P drops but the alk is high, both zooxanthellae and the coral cells require N and P. Since there is not enough N and P for the both, coral expels some of the zooxanthellae to reduce the demand, hence they turn pale. This is followed by the paling of the parts of the coral that receive more light. In these tissues, coral growth is slow (but there still is growth as branches get thicker over time), but since they get good light algae still need N and P. If N and P are low, coral expels them to reduce the population. Otherwise they will drain the coral cell of N and P. The last parts to get pale are the shaded regions since the N and P demand of the algae living there are the lowest.

Now the actual tip burning (tissue necrosis) happens becouse of rapid N and P drops. In this case N and P become limiting so fast that coral doesn't have time to expel the zooxanthellae. THis cause an extreme N and P starvation. This cause generation of reactive oxygen (ROS) species that kill the cells.

So why does ROS form? It is because the mechanism how photosynthesis operate. This is true for zooxanthellae, cynaboacteria or higher plants. Photosynthesis is simply a process that cannot be turned off. Higher plants have the most complex regulation over this (and regulation corals have is no where near to what higher plants have) and they try to control it by moving their leaves or moving their chloroplast, etc to achieve shading, but even then they have a tolerance limit. Chlorophyll will simply continue to harvest light energy, if there is not enough N and P to produce the enzymes (require N) and ATP (require P) to harvest and distribute this energy, that energy will be dissipated by transferring it to oxygen and water molecules. This forms the highly reactive oxygen intermediates that simply burn the cell from inside out. And this results in tissue necrosis.

So long story short; low N and P require alk to be low as well, because high alk put more demand on N and P from the corals as well. When there isnt enough N and P for both the coral and the zooxanthellae. Zooxanthellae gets kicked out.



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Old 12/07/2017, 07:11 PM   #15
bertoni
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Ok part 2. Why has the vodka dosing caused my alk dosing to nearly double?
That increase in consumption might be due to increased coral and coralline growth. That'd be my first guess.


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Old 12/07/2017, 07:15 PM   #16
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I nature corals grow in very low soluble nitrate and phosphate levels (almost in trace amounts) and the alkalinity of natural sea water is around 7.5dKH.

In a tank if you try to replicate the low nutrient levels (through carbon dosing and subsequent consumption of nitrate and phosphate), you need to lower alk as well.

The reason for this is not very clear. But from a very simplistic point of view
...
That's an interesting hypothesis. I hadn't thought much about ROS being an issue, but that's possible. We'd also need to know how corals control the calcification process to begin to validate this theory.


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