Couple different questions.

[Triggerjay]

First question:
Randy, how do you feel about anaerobic sulfur denitrification? After researching it I see that the effluent will have a lower ph than the display. I see this can be compensated by using crushed coral. The design I have seen commercially stack the suffer media, then a layer of crushed coral above it, and have a recirculating pump constantly moving water through the layers. How effective would this be to raise PH? Would it be more effective to have a seperate chamber for the crushed coral that only the effluent goes through vs recirculating while the suffer media continues to recirculate? And is there any drawbacks to a suffer denitrification system you can think of? Excess suffer buildup or unwanted elements introduced to the display?

Second question (not related):
I have a 65g SPS dominated tank. I dose esv two part. I have a couple large colonies and about 30 or so frags. Growth has been good, but the tank uses little alk. I dose 8ml of each part daily to maintain 8dkh, 420ca. I see people with similar setups to mine that have to dose much larger amounts of two part to maintain. Should I be questioning my low consumption? It should be noted I do a 15g water change bi-weekly.

Thank you!

 

[Oceansize]

I use the Korallin sulphur denitrator and it is my favorite piece of equipment. I will never build another tank without one.

The crushed coral doesn't raise pH in the effluent, it merely lessens the drop. The Korallin sulphur denitrator uses crushed aragonite on top of the sulphur pellets, and my tank's pH dropped only by a net 0.1. (was 8.4, dropped to 8.3). I took out the crushed aragonite recently and fully filled the chamber with sulphur and my pH is now 7.9. So the crushed coral in the denitrator in my case keeps the pH drop to only 0.1 instead of 0.6. Keeping in mind that I also use a calcium reactor which also tends to drop my pH so you might have even better results.

The benefit is I can now tweak my Nitrates anywhere from barely detectable to 5 or 6 ppm with relative ease and zero maintenance. I say zero maintenance only after the reactor is dialed in which can take a month or so. And maybe refreshing the sulphur every other year or so, lol. Since adding the denitrator, I change my water maybe twice a year.

The negative with these is the possibility of sulfate buildup, but as far as I'm aware that negative is pretty much theoretical at this point, as we're not aware of anybody reporting a tank crash due to sulfates where a denitrator is involved.

The sulfate buildup would be the result of too little recirculation (too slow of an effluent drip rate), since sulfate is created only after all the nitrates have been consumed, and is easily noticed due to the distinctive rotten egg smell coming from the effluent.

I've been using mine 1.5 years and only experienced this once while out of town because the effluent drip rate slowed. I merely increased the drip rate back to where it was supposed to be, did NOT do a water change, and everything was fine, no issues.

 

[Triggerjay]

I knew the aragonite raises ph, and depending on the ph lowered by the sulphur will also add calcium and alk (same principal as ca reactor) but I was wondering by separating and having only the effluent go through the aragonite if it will increase the ph raising ability vs recirculating through the sulphur media AND aragonite. I know what I'm thinking, just having a hard time explaining it in text. Lol

 

[Oceansize]

I see what you're saying: if the _recirculated_ effluent was only going through aragonite instead of sulphur AND aragonite after being denitrated, then shouldn't that mean the pH doesn't drop as much if at all, right? There would be more buffering effect as a result, right?

A second chamber with just aragonite in it would work for that purpose, however the chamber with sulphur in it would still need to be recirculated too, as the system will not achieve sufficient denitrification with only one pass through the sulphur.

So if both chambers need to be recirculated, then might as well just combine 'em, so no I don't see much benefit of separating the two processes.

Also, this was a big revelation for me: a calcium reactor does not consume alkalinity, but a sulphur reactor DOES consume alkalinity. Therefore, a calcium reactor delivers Alk and Calcium in exactly the same ratio as they are consumed by coral and therefore using a CA reactor does not create an imbalanced ratio between Alk and Ca. HOWEVER, since a sulphur denitrator does consume Alk, it does NOT deliver Alk and Ca in the exact same ratio as they are consumed by coral. If your denitrator's effluent is adjusted so that Alk remains stable, Calcium will slowly rise over time. If your denitrator's effluent is adjusted so that Calcium remains stable, Alkalinity will slowly decline.

Therefore, most of us adjust so that Alk remains as stable as possible, and as a result Calcium creeps up in our tanks, which fortunately isn't a very big deal until calcium REALLY gets high (800's?), at which point water changes can address. After 1.5 years, my calcium is now slightly above 500 while my Alk is between 8 and 9. No worries about high calcium yet.

 

[Triggerjay]

I use the Korallin sulphur denitrator and it is my favorite piece of equipment.

How often do you bleed off the nitrogen gas?

 

[Triggerjay]

I see what you're saying: if the _recirculated_ effluent was only going through aragonite instead of sulphur AND aragonite after being denitrated, then shouldn't that mean the pH doesn't drop as much if at all, right? There would be more buffering effect as a result, right?

A second chamber with just aragonite in it would work for that purpose, however the chamber with sulphur in it would still need to be recirculated too, as the system will not achieve sufficient denitrification with only one pass through the sulphur.

So if both chambers need to be recirculated, then might as well just combine 'em, so no I don't see much benefit of separating the two processes.

Also, this was a big revelation for me: a calcium reactor does not consume alkalinity, but a sulphur reactor DOES consume alkalinity. Therefore, a calcium reactor delivers Alk and Calcium in exactly the same ratio as they are consumed by coral and therefore using a CA reactor does not create an imbalanced ratio between Alk and Ca. HOWEVER, since a sulphur denitrator does consume Alk, it does NOT deliver Alk and Ca in the exact same ratio as they are consumed by coral. If your denitrator's effluent is adjusted so that Alk remains stable, Calcium will slowly rise over time. If your denitrator's effluent is adjusted so that Calcium remains stable, Alkalinity will slowly decline.

Therefore, most of us adjust so that Alk remains as stable as possible, and as a result Calcium creeps up in our tanks, which fortunately isn't a very big deal until calcium REALLY gets high (800's?), at which point water changes can address. After 1.5 years, my calcium is now slightly above 500 while my Alk is between 8 and 9. No worries about high calcium yet.

Yes, recirculate sulpher, but one pass the aragonite on the way back to the tank via a second chamber. That is what I am trying to say. [emoji12]

 

[Triggerjay]

Wow, I just noticed how bad my phone butchered "sulphur"

 

[Oceansize]

How often do you bleed off the nitrogen gas?

If you set it up right, you won't need to bleed off any gas. Most people who have gas buildup are not following hydraulic principles and have too much slack in their hoses. I avoided any gas buildup entirely, even during the break-in phase, by merely making sure that my hoses didn't have any downward dips in them as they exited the reactor. Seriously, I never once have had to use the valve on top to bleed excess gas. Keep in mind that the nitrogen gas that is SUPPOSED to be in the water escapes with the effluent and you never notice it because the bubble size is WAY too small. Any buildup at the top of the chamber is due to pressurization issues and indicates improper hose wrangling; it is not part of the normal functioning of the reactor.

 

[Oceansize]

Yes, recirculate sulpher, but one pass the aragonite on the way back to the tank via a second chamber. That is what I am trying to say. [emoji12]

One pass through the sulphur won't achieve enough denitrification, so that reactor should have a recirculating design/pump. And one pass through the aragonite won't achieve enough buffering, so that reactor should have a recirculating design/pump as well. So if you're trying to get more buffering effect, it seems to me the better thing to do would just play with the ratios of sulphur pellets to aragonite in the chamber. Following the instrux leaves you with about 2/3's sulphur pellets, 1/3 aragonite. Maybe reverse those ratios and see what happens? 1/3 sulphur and 2/3 aragonite would provide more buffering, but also less denitrification. So if you were to try it and were happy with where your tank pH settled but unhappy with the amount of denitrification, well then keep the ratios intact but use a bigger reaction chamber.

Or, just follow the instructions and be perfectly happy with what you get since it's already a great design, lol. We're talking a pH drop of 0.1, not really worth worrying about.

 

[Oceansize]

If I haven't already made it clear: the crushed coral in a sulphur denitrator, while it is enough to keep pH from dropping materially, it is NOT enough to keep the Alk at a consistent 9 dkh. You will still need a method for supplying Alk to the tank. That is why I use a calcium reactor as well.

 

[arman]

First question:
Randy, how do you feel about anaerobic sulfur denitrification? After researching it I see that the effluent will have a lower ph than the display. I see this can be compensated by using crushed coral. The design I have seen commercially stack the suffer media, then a layer of crushed coral above it, and have a recirculating pump constantly moving water through the layers. How effective would this be to raise PH? Would it be more effective to have a seperate chamber for the crushed coral that only the effluent goes through vs recirculating while the suffer media continues to recirculate? And is there any drawbacks to a suffer denitrification system you can think of? Excess suffer buildup or unwanted elements introduced to the display?

Second question (not related):
I have a 65g SPS dominated tank. I dose esv two part. I have a couple large colonies and about 30 or so frags. Growth has been good, but the tank uses little alk. I dose 8ml of each part daily to maintain 8dkh, 420ca. I see people with similar setups to mine that have to dose much larger amounts of two part to maintain. Should I be questioning my low consumption? It should be noted I do a 15g water change bi-weekly.

Thank you!

I have 10 lps and one sps recently and every 2 days the kh drops from 8 to 7.
Is it coral consuming or it preticipate?
I asked this cause yor second question was that u think they consume not much.

 

[Oceansize]

I have 10 lps and one sps recently and every 2 days the kh drops from 8 to 7.
Is it coral consuming or it preticipate?
I asked this cause yor second question was that u think they consume not much.

I think the reason the OP's consumption rate isn't very high is because he's doing frequent water changes. Every water change replenishes Alk and Ca, therefore the more water changes, the less need for dosing. Your Alk wouldn't be precipitating unless something else were really out of whack, therefore I would assume your coral is eating it.

 

[Triggerjay]

I have 10 lps and one sps recently and every 2 days the kh drops from 8 to 7.
Is it coral consuming or it preticipate?
I asked this cause yor second question was that u think they consume not much.

Yes, I question that I ONLY have to dose 8ml of ESV to maintain 8dkh. I see similar size tanks/similar inhabitants using far more 50-75ml to maintain. I get a 2dkh drop every two days without supplementation. If I increase ESV even 1ml/day I see an increase in alk in the display. It just seems as though my tanks consumption is far less than the "average" for similar sized tanks. I check alk 2 times weekly and it stays rock solid at 8dkh (where I want it) on 8ml of part 2. I'm not saying it is something to be concerned with as everything is looking great and growing like mad. I don't intend to change this as its working. Just curious as to why my consumption varies greatly from "average".

 

[Triggerjay]

I think the reason the OP's consumption rate isn't very high is because he's doing frequent water changes. Every water change replenishes Alk and Ca, therefore the more water changes, the less need for dosing. Your Alk wouldn't be precipitating unless something else were really out of whack, therefore I would assume your coral is eating it.

Yes, very possible. Those that I see running higher two part may not be doing frequent wc's. I also match alk to 8 in my new saltwater (usually have to lower with muratic acid).

 

[Randy Holmes-Farley]

I discuss this method, including issues with alk depletion/calcium elevation here:

Nitrate in the Reef Aquarium - REEFEDITION
http://www.reefedition.com/nitrate-in-the-reef-aquarium/

from it:

Sulfur Denitrators

In these systems, bacteria use elemental sulfur and produce N2 from the sulfur and nitrate according the following equation (or something similar):

2 H2O + 5 S + 6 NO3– → 3 N2 + 5 SO42- + 4 H+

The production of acid (H+) in this reactor can tend to reduce the aquarium alkalinity. It has also been suggested to pass the effluent of such a reactor through a bed of aragonite to use the acid (H+) produced to dissolve the calcium carbonate, and thereby provide calcium and alkalinity to the aquarium. While that is a fine idea, it doesn’t add much calcium and alkalinity to most aquaria.

To estimate the magnitude of the effect, we start with a liberal estimate of how much nitrate might be removed. Say 10 ppm of nitrate per week.

10 ppm nitrate = 0.16 mmole/L of nitrate

Since 4 moles of H+ are produced for every 6 moles of nitrate consumed, this will produce

0.107 mmoles/L of H+ per week

How much calcium this could produce?

Assume that it takes one proton to dissolve one calcium carbonate:

CaCO3 + H+ → Ca2+ + HCO3–

Clearly, this is a substantial overestimate because much of the acid will be used up driving the pH down to the point where CaCO3 can even begin to dissolve. Consequently, we have an upside limit of 0.107 mmoles of Ca2+per week. Since calcium weighs 40 mg/mmol, that’s 4.3 ppm Ca2+ per week.

For comparison, an aquarist adding 2% of the tank volume in saturated limewater daily is adding on the order of 16 ppm of calcium per day. Consequently, this method may not be especially useful for maintaining calcium. Additionally, the acid produced will have a long term lowering effect on the alkalinity. In fact, it is double dipping on the alkalinity depletion since alkalinity is consumed when the nitrate is produced, and again when it is removed in the denitrator. So if you use a sulfur denitrator, be sure to monitor the alkalinity in the aquarium.

 

[arman]

I use red sea powder for ca and kh both.
And one scoop every2 days.
I was worried that its too much,but now i think its not very much.