Sulfur Denitrator depletes alkalinity

[Long Island Andy]

Hi

I have been running sulfur denitrator's for years and really like them. Unfortunately these is a limited amount of information I can seem to find.
I having an issue with calcium increasing and alkalinity diving in one of my systems

The tank is a 65 gallon soft coral heavily populated fish reef tank. The denitrator has been on the tank for over a year. I do not dose any kalk, alk or calcium to this tank and do 20 gallon bi-weekly water changes. My calcium level is currently over 600 and the dkh is 4. I have added as much as 12ozs of alk and the dkh moves to about 8 but drops by the next day. So I figured the calcium/alk ratio was so off i'd never be able to balance so I made up 70 gallons of new salt water and did 100% water change. Water going in had calcium of 420 and dkh was 7. Well within a week calcium was almost 580 and dkh 4
Sorry for being so long winded so my question is: Can the denitrator be causing this inbalance

Thanks

[scuzy]

Denitrator adds calcium to your water as you have calcium media in there right? At least that's what's in mine on top of the sulfur media. I never notice and alk depletion. Maybe your curls are consuming a lot of all or precipitating out?


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[Long Island Andy]

Originally Posted by scuzy

Denitrator adds calcium to your water as you have calcium media in there right? At least that's what's in mine on top of the sulfur media. I never notice and alk depletion. Maybe your curls are consuming a lot of all or precipitating out?


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It does run through aragonite media maybe that is where the calcium is coming from but I don't understand the constant depletion of the alk

[Greg 45]

I run a large sulfur denitrator with a calcium reactor . There is no aragonite on the top or bottom of the sulfur in the reactor . My calcium also reads high any where between 542 to 603 0n a triton test. Calcium seems to read higher on a hobby grade test kit. You might want to put this in the chemistry forum you might get more answers .

[bertoni]

The denitrator will consume alkalinity. See section 7 in this article:

http://www.advancedaquarist.com/2003/8/chemistry

A drop of 3 dKH in a week seems like a lot, but that might be what's happening. Is that 3 dKH number correct?

[Long Island Andy]

Originally Posted by bertoni

The denitrator will consume alkalinity. See section 7 in this article:

http://www.advancedaquarist.com/2003/8/chemistry

A drop of 3 dKH in a week seems like a lot, but that might be what's happening. Is that 3 dKH number correct?

Hi Jon, it is crazy. No matter how much alk I add it will only raise in for a day or 2. I am dosing 140ml of alk a day in a 65G tank and my dkh readings are around 4 or 5, The calcium increases daily . I hate to take the denitrator off line because it keeps my nitrates at zero in this heavily stocked heavily fed tank but I am going to just to see what happens. I run 2 other sulfur denitrators in tanks with calcium reactors and they don't have the alk problem. Maybe the high alk coming out of the calcium reactors offsets it
Thanks for the response
Andy

[Vinny Kreyling]

Andy, Mike has a mini-cal for cheap if you want another unit.

[tmz]

Yes it does depleteralkainity.The article cited explains it. The simplified reaction is : 2H2O(water) +5S (sulfur)+6NO3(nitrate )---->3N2(nitrogen gas) +5SO4(sulfate) + 4 H+ .The extra H+ depletes the alk .
I haven't used my DIY sulfur dentirator in quite a while but had no trouble with alk given kalk dosing and occasional supplementation with sodium carbonate(baked baking soda)

[Long Island Andy]

Originally Posted by tmz

Yes it does depleteralkainity.The article cited explains it. The simplified reaction is : 2H2O(water) +5S (sulfur)+6NO3(nitrate )---->3N2(nitrogen gas) +5SO4(sulfate) + 4 H+ .The extra H+ depletes the alk .
I haven't used my DIY sulfur dentirator in quite a while but had no trouble with alk given kalk dosing and occasional supplementation with sodium carbonate(baked baking soda)

Thanks for the response, I don't have any problems with the other tanks where I run the denitrators. They both have calcium reactors on them where the effluent coming out of the C/R at about 35dkh which is normal for me. I really believe the tank where it is depleting the alk has all soft corals and needs no supplementation other then water changes. The crazy thing is by depleting the alk the calcium goes through the roof without me adding it. I am going to take the sulfur reactor off line but have to wait for the wife to be out of the house lol

[bertoni]

It'll be interesting to see what effecting taking the reactor off line will have. Please keep us posted! I'm not sure exactly what's happening here.

[josephxsxn]

Maybe you have a Magnesium imbalance? It does appear there is a relationship to Magnesium and its ability to slow down precipitation.

http://www.advancedaquarist.com/2003/10/chemistry

In Captive Seawater Fishes there is an extensive discussion of the impact of magnesium on the calcium/carbonate system, including a set of data that indicates the magnitude of the impact that magnesium can have.25 In this experiment, batches of artificial seawater were made up with varying magnesium and carbonate levels. The scientists then measured how long it took for calcium carbonate to precipitate from each solution. Not surprisingly, the higher the carbonate was raised, the more rapid was the precipitation of calcium carbonate.

More interestingly, the magnesium levels were found to have a very large impact on the rate of precipitation. In batches with no magnesium, and at natural calcium and elevated carbonate levels, calcium carbonate was found to precipitate in minutes. With a natural seawater level of magnesium added to that mix, the precipitation was delayed to 13 to 20 hours. With double the natural magnesium concentration, the precipitation was delayed to 22 to 29 hours.

[bertoni]

To Reef Central

Magnesium acts to foul crystal surfaces and thus reduce abiotic precipitation. That's one of the reasons that the surface waters of the ocean can run at supersaturation with respect to calcium carbonate. The equations for a sulfur reactor are different, though, and the cause is not precipitation.

[ianmoede]

What was the outcome of your experience?

[coralcruze2020]

interesting. does the denitrator reactor use up alk or does the depletion of n03 somehoe use it up? I am interested to know if there is an effect on alk with change in no3 levels. anyone know?

[bertoni]

The denitrator will consume some alkalinity due to the production of sulfuric acid. Converting nitrate to nitrogen gas actually releases alkalinity.

https://www.advancedaquarist.com/200...try#section-12
http://reefkeeping.com/issues/2004-12/rhf/index.htm

[ianmoede]

I don’t think that’s correct. The downside to sulfur denitrification is that it consumes alkalinity. I can see this right now in my own take with no coral but an alkalinity demand as monitored by a kh guardian.


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[coralcruze2020]

very very interesting... anyone have a quantifiable amount of alk being used here?

[bertoni]

The formula given was 4 H⁺ per 6 NO₃^-. It's a very small amount. If the reactor is removing 10 ppm nitrate per week, I think the change in dKH would be about 0.6 dKH per week. I need to check another equation and double-check my math, though.