DSB in a bucket can possibly function as a Ca reactor

[Gary Majchrzak]

If using aragonite sand in a "DSB in a bucket" could it be possible that the contraption also delivers Ca and alkalinity to a system while it's lowering nitrates?
If the pH in the DSB bucket isn't low enough could CO2 be regulated to accomplish such an environment?
Has anybody played around with this idea?

 

[old salty]

It would probably become the most inefficient Ca reactor on the market.

I only say this, because I use lots of CO2 in my planted FW aquarium. Adding CO2 to your bucket (which should have a lot of water going across the top), would only waste CO2. It would float to the top and dissipate. When CO2 is added to a reactor, the very spot where CO2 is introduced is critical and usually located where the incoming water can force the air bubbles to the bottom of the reactor, allowing more contact time; enough where the CO2 actually dissolves in the water.

In my FW tank, I am actually using a contraption which makes the CO2 bubbles remain in the water for a longer period (Hagen ladder). If I were to simply add CO2 to the tank, it would take a lot more to do a lot less.

 

[Gary Majchrzak]

good point.
More food for thought:
On a similar plane of thinking, could a large deep Ca reactor reduce nitrates?

 

[Qcks]

According to this thread, Yes, A remote DSB can remove nitrates.

It's been tried and tested by many people.

The concept makes sense since you're relying on the metabolic action of cryptic, anaerobic, chemotrophs to facilitate nitrate removal.

As detailed, the process seems to have some down sides, but i have some ideas for fixin' those problems. One of my favourite subjects (i'm kinda weird this way) is methanogenisis.

People who run methane generators, especially for prolonged periods of time, have similar problems to the ones described. I wonder if the solution might be the same.

In methane generators, Carbohydrate and Nitrate need to be kept in a specific balance. I think that the problems described in the remote DSB thread corespond to carohydrate deficiencies in the chemotroph's environment. This accounts for the variability in the success with the method, as well as for the cycling that seems to occur. People With a low TDS would see less results since the bacteria wouldn't have an adequate carbon receptor to facilitate the removal of nitrate from the environment. Chemotrophs are simply another form of hetereotroph, and many are capable of predating other microorganisms, or even cannabalization.

Also as a final note on the Remote DSB, i see alot of people wondering why a DSB would need to be unlit and not very well oxygenated for the method to work. From readings that i've done on anaerobic detrivores that live in the soil, they're one of the few organisms that can fix atmospheric nitrogen into nitrates (the organisms really do need nitrate that badly.). Allowing light and Atmospheric air to reach the substrate is only going to facilitate this an environment where the opposite of the desired effect occurs.

In regard to the Deep Calcium reactor....
It depends on how you ran it. Since you mentioned Dosing Carbon dioxide, i remember briefly skimming a thread a few months back that talked about Calcium acetate. It might be something worth looking into. If you're in the US you have to make it though, but since all you need to make it is powdered Lime and cold White Vinegar, it shouldn't be too much of a problem. I do have to warn ya though, this is effective carbon dosing, since acetate is a simple organic molecule, and it could result in a bacterial bloom.

 

[Gary Majchrzak]

thanx for that link. Looks like I need to do some reading!

 

[Gary Majchrzak]

I see that my old friend mr.wilson touched upon my question in that thread:

<a href=showthread.php?s=&postid=9056463#post9056463 target=_blank>Originally posted</a> by mr.wilson
Calcium reactors deliver a PH of 6.5 over a great area with a flow through for maximum exposure. The dissolution rate in a calcium reactor is about 50% of the media per year. The dissolution rate of media in a DSB is about 5% per year.

I don't know where he got those numbers, but if taken as fact it would seem to indicate that a large enough aragonite based DSB/RDSB can act as a significant source of Ca/alk.

 

[thriceanangel]

<a href=showthread.php?s=&postid=10299713#post10299713 target=_blank>Originally posted</a> by Gary Majchrzak
I see that my old friend mr.wilson touched upon my question in that thread:

I don't know where he got those numbers, but if taken as fact it would seem to indicate that a large enough aragonite based DSB/RDSB can act as a significant source of Ca/alk.

Who knows where mr.wilson ever gets his numbers from. But it seems to me Gary that your idea has merit. I have used about every type of nitrate reduction technique known at one point or another, and I think that you could certainly combine the two. It may take quite a bit of CO2, but who knows, it may be efficient enough to use in larger systems

 

[RichConley]

I would think that if you introduced CO2 underneath the sand, it would percolate up through, and be much more effective.

 

[Daemonfly]

I always see the "sand bed helps buffer/add Ca/etc.." argument debated, but not sure which side (or which info from each side) to believe just yet.


But as for the RDSB modifications listed here, I'd be careful, as CO2 moving through the bed might create enough flow to disturb the aerobic & anaerobic layers. I'd guess it would have to be a slow system.

Also, since it's the CO2 that lowers the pH enough to dissolve the aragonite, what happens during this process, and do those Oxygen molecules get released from the CO2, then ruining the denitrating process?

 

[scarter]

well you need the CO2 to lower the Ph so that the medium will dissolve correct? if that is the case can the bacteria live in the lowered Ph? I think you may run the risk making the whole bed sterile. any thoughts on this?

 

[cayars]

Why not just add sufur beeds/pellets to the RDSB? This will lower your pH like CO2 additions would.

In any event your not going to get the same performance from this as you would a full blown Calcium Reactor but every little bit helps.

Carlo

 

[Serioussnaps]

Search reefkeeping mag by author...Eric Borneman discusses Jaubert attempting this I believe. You probably have read that article already, but it does discuss using a sandbed for this and concludes it to be highly inefficient at adding CA/ALK. It would add some but I dont know what your expectations are. Certainly not enough to grow even a small load of skelatal building organisms FWIW. Of course it is going to reduce your nitrates quite efficiently.

 

[token]

If the DSB is used in conjunction with a plenum, then the result does actually provide some calcium and buffering. The big question is would it be enough for the system's occupants.

The "in a bucket" issue would be the problem for me. I maintain as much surface area in my DSB as I do in my tank. I have about 4" of sand above my 3" plenum. That volume of sand reduces over the course of a year but it is sufficient to maintain both my alkalinity and provide enough calcium that my LPS's grow, albeit slowly, my clams add shell, again, slowly, and my coralline production is chronic. I do add a 20# bag of fresh live sand as needed but I have not removed any of the sand in my oldest DSB in the five years it has been running.

The nature of the plenum is critical. Though its pH is not as low as a Ca reactor's, it is lower than the water in the tank and low enough to slowly erode the media above it. A Ca reactor's chamber is much lower and dissolves the media much faster, providing more available Ca reliably.