Using a sulfur denitrator and adding/dosing sulfate

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Jon_W79

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If someone is using a sulfur denitrator, and they are adding sulfate,(because they use a calcium reactor or dose two part)should they reduce or stop adding sulfate since the sulfur denitrator is adding sulfate to the reef tank? Can someone at least answer this question in a general way?

A sentence from part of a paper I posted below says "Based on the stoichiometric equation for autotrophic denitrification (Batechlor and Lawrence, 1978a, 1978b) for reduction of every 1mg/l of NO3--N, approximately 7.1mg/l SO42- should be produced."
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Jon_W79

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@Belgian Anthias made a post on RC that said for every mol of nitrate removed by a sulphur denitrator 1.1 mol of sulphate is produced. Belgian Anthias can you tell me where you got that information?
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Belgian Anthias

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Everything about BADES is available in our knowledge base, the Makazi Baharini Wiki . The wiki is written in Dutch and the articles are very well documented. Most references can be consulted and most of them are in English. Some of the articles are translated into English but are not updated. Use your preferred translation aid if needed. The info available in Makazi Baharini may contain by law protected content and is consultable for personal use only. To make full use of the wiki one has to register. On the bottom of each page, one has the possibility to make comments and remarks concerning the content of the page.
About the sulfate cycle using BADES.
 
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Randy Holmes-Farley

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Sulfate addition is a very minor concern because sulfate is naturally very high (2700 ppm) so a little added makes no difference, unless you are doing no water changes for a very long time . Exact sulfate values are totally unimportant. A bigger concern that needs to be dealt with somehow is alkalinity consumption by sulfur denitrators.

Many folks have the opposite issue: they dose calcium chloride without offsetting sulfate and sulfate gets depleted over time. In my DIY 2/3 part, I add the sulfate via magnesium sulfate.
 
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Jon_W79

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Sulfate addition is a very minor concern because sulfate is naturally very high (2700 ppm) so a little added makes no difference, unless you are doing no water changes for a very long time . Exact sulfate values are totally unimportant. A bigger concern that needs to be dealt with somehow is alkalinity consumption by sulfur denitrators.

Many folks have the opposite issue: they dose calcium chloride without offsetting sulfate and sulfate gets depleted over time. In my DIY 2/3 part, I add the sulfate via magnesium sulfate.
I think you may have misunderstood what I was saying(it's probably my fault). I'm not concerned about exact sulfate values. I'm wondering why I'm dosing magnesium sulfate if my sulfur denitrator is adding a significant amount of sulfate, especially since my tank has a low alkalinity and calcium demand. Would dosing magnesium sulfate only be useful if the alkalinity and calcium demand reaches a certain level(maybe a high to very high level)?
 
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Belgian Anthias

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I think you may have misunderstood what I was saying(it's probably my fault). I'm not concerned about exact sulfate values. I'm wondering why I'm dosing magnesium sulfate if my sulfur denitrator is adding a significant amount of sulfate, especially since my tank has a low alkalinity and calcium demand. Would dosing magnesium sulfate only be useful if the alkalinity and calcium demand reaches a certain level(maybe a high to very high level)?
Is not because the BADES proces produces sulfate and consumes alkalinity this also must influence the water quality of the system. Not only that specific process takes place. If managed and used correctly most effects of BADES may be neutralized before the treated water is added to the system water. Using BADES in a reactor that is big enough in combination with enough lime is all that is needed.
Using BADES, mixing some dolomite to the used substrate will provide calcium and magnesium and limit the need for dosing magnesium sulfate. Magnesium sulfate may be produced? Mg + H2SO4

If enough calcium carbonate is used most sulfate will settle on the lime and can be removed when refreshing the lime.
In the MAAO several samples were taken of used maerl and it was found that the maerl in use behind a sulfur column contains on average up to twice as much sulfate than fresh maerl and used as maerl in the aquarium. Fresh maerl contains 219 mg sulphate / gram, maerl in the aquarium 220mg / gram, maerl in the lime columns after the sulfur column an average of 421mg per gram of maerl. (Hignette2001) Per gram of maerl - 200mg of sulfate can therefore be stored! (ref: MB CMF de Haes 2017)
 

Randy Holmes-Farley

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I think you may have misunderstood what I was saying(it's probably my fault). I'm not concerned about exact sulfate values. I'm wondering why I'm dosing magnesium sulfate if my sulfur denitrator is adding a significant amount of sulfate, especially since my tank has a low alkalinity and calcium demand. Would dosing magnesium sulfate only be useful if the alkalinity and calcium demand reaches a certain level(maybe a high to very high level)?

Well, if you use different products or methods that add the same thing, then yes, it can become an issue to determine how much is needed or undesirable.

If you like and want to keep using a sulfur denitrator, I'd probably consider using only magnesium chloride. Only an ICP test will tell you whether that is still too much sulfate, or not enough, or just right. :)
 
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Jon_W79

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Well, if you use different products or methods that add the same thing, then yes, it can become an issue to determine how much is needed or undesirable.

If you like and want to keep using a sulfur denitrator, I'd probably consider using only magnesium chloride. Only an ICP test will tell you whether that is still too much sulfate, or not enough, or just right. :)
Thank you for the general recommendation. I can't really put this in perspective at all. I know you can.
 

Randy Holmes-Farley

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Thank you for the general recommendation. I can't really put this in perspective at all. I know you can.

In the scheme of things to worry about in a reef tank, this seems near the bottom of the list. :)
 

Belgian Anthias

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Although the ICP-OES is currently the highest quality analysis method available for marine aquarists, it has certain problems that can impact the accuracy and precision of the seawater results especially with smaller ranges of trace elements. For macroelements, a single flow process (single pass) gives you fairly good results of 3-5% accuracy. Sending the same samples to different labs the difference between laps was sometimes up to 10% (ref: https://reefhub.pl/test-of-marine-salts/)
About ingredients of salt mixes, the difference between different batches of the same mix may be up to 3% ( fabrication tolerance ) About the sulfate ( sulfur) content in fresh-made seawater the difference between different salt-mixes is 20%, but can go up to 50%.
Older versions of Balling’s methods have suggested the use of magnesium sulfate (MgSO4), that this could lead to sulfate accumulation in a system where its consumption is very low is something one may read in many publications.
In many cases, sulfate consumption is about the production of HS and other sulfur compounds and precipitation. Usable sulfur compounds are very important. If used, sulfate is produced.
As far as I know, the level of sulfate will not affect natural processes exempt if there is not enough.
This does not mean a high sulfate level is innocent, it means problems are not reported, could not be linked ( yet).
For this reason, trying to have control over the sulfate production in a closed system may be part of good management.
 
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