Weekly Discussion - BB vs DSB

[Anonymous]

what i am getting from some of the threads is that the dsb will collect and release phosphorous over the long haul.

Sand will collect phosphates and if the sand is 'filled' it will re release them.

if you have a very effective and efficient fuge/algae filter...shouldn't it absorb whatever phosporous/nitrate/algae fertilizer is thrown off?

Maybe. IIRC the problem is that the phosphate is pretty deadly to corals. The question is how much and how long is dangerous. Galleon?

Then you gotta figure out how to test for it.

 

[Anonymous]

so has there been any more discussion regarding coral species kept in each type of system?
i can't keep up with all these darned threads and i know it came up more than once.
has there been any agreement between the thread participants that inverts like Goniopora and alveopora do better in a DSB tank? or the increased success with Xenia?
pardon me if i am wrong, but it seemed as though few could successfully keep these corals until DSBs became widely used.
maybe there are species of soft corals that are necessary for the long term success DSB?

 

[Mouse]

Thanks for the replys Galleon, Seems Macro's arn't the cure all i thought theu were. So what about this for a solution to the DSB Nutrient Sinking problem.

A twin compartmented Phlenum DSB sump. Basically there would be a tap into the void portion of the phlenum allowing you to drain water through it. In this instance with there being two compartments you could drain one, whilst still preserving the oxyegen free dentrifying proerties of the other compartment. Would this be sufficient at removing all of the sunk nutrients? or am i just gettiing too complicated for the sake of the denitrifying properties of a DSB, when infact LR would do it.

It would be nice if we could cullminate this conversation into a solution that both camps would be happy with. Im sure we can discuss this through.

 

[Anonymous]

Pod, there has been some discussion of animals needing sand needing sand. IIRC, it wasn't a very exhustive discussion. From the pics I have seen of the vocal BB proponents, they are almost all sps tanks.

 

[Jolieve]

Podman makes a very valid point. How do the bare bottom users answer to that?

J.

 

[Anonymous]

Podman makes a very valid point. How do the bare bottom users answer to that?

J.

IIRC the answer is use sand for animals that need it. SPS do not.

 

[Anonymous]

Maybe. IIRC the problem is that the phosphate is pretty deadly to corals. The question is how much and how long is dangerous. Galleon?

Good question, with several variables. Organic phosphorous toxicity all depends on the actual compound, the coral being affected, and the concentration

As a baseline, at concentrations of under 1 micromolar dissolved phosphorous, gonad development shuts down and fertilization fails.

or am i just gettiing too complicated for the sake of the denitrifying properties of a DSB, when infact LR would do it.

Pod, there has been some discussion of animals needing sand needing sand. IIRC, it wasn't a very exhustive discussion. From the pics I have seen of the vocal BB proponents, they are almost all sps tanks.

Initially, almost any Zoantharian (hexacorallian) or Alcyonarian (octocorallian) that does well in a typical forereef, backreef, or reef flat scenario can and is cultured with very good success (no mortality, growth rates comparable to what is seen in the wild) in the bare bottom systems I described. I can tell you that from a great deal of first hand experience. Secondly, this highlights the issue that many aquarists try to keep corals in the same systems that are not compatible in such small volumes, usually due to production of secondary metabolites, like terpenoids. It’s well known that secondary compounds from many Alcyonaria shut down settlement in and can kill many species of hermatypic corals directly downstream

pardon me if i am wrong, but it seemed as though few could successfully keep these corals until DSBs became widely used.
maybe there are species of soft corals that are necessary for the long term success DSB?

Pod, it’s me you’ll have to pardon on this one, because I dunno.

 

[middletonmark]

Yep, it's partially at least about the creatures/corals you want to keep. Not that DSB's make Gonipora and some others that much easier to keep - at least from my anecdotal experience it doesn't seem like there's that much better success than there used to be. Maybe incrementally, but not widespread from what I know. [but I don't know everything, not even close]

In my mind, some corals `like' things a little dirtier [or nutrient rich] ... where many of the `barebottom crowd' are looking for SPS tanks, which react more adversely to nutrients and phosphorus, IMO. They also can handle the major flow, aiding the heavy wet skimming that's required in a BB system.

I think a major point to all this is that no method is completely `plug and play' like the Dr. DSB method was considered to be. All require the `right' ingredients/setup to last and work well.

I think only recently has it been stressed that setting up a DSB [or any tank] is not as Ron said once `as easy as falling off a log'. Provided you're aware of problems ... at least you're ahead of the game a little bit. Sadly, nothing is simple ...

Personally, I'm not convinced wholesale by either end of the argument. I'm skeptical enough to realize that most likely, all systems have some sort of problems. These are closed systems - meaning we can only get somewhat like a `real reef' before the closed system is a major factor.

Anyway ... Thanks to Galleon, for jumping in here. It's good to have someone who knows the literature helping us along in this discussion.

 

[Anonymous]

My impression about the Goniopora is that more hardy species have been imported lately, and the species that caused the difficulty before is still considered difficult.

 

[liquid]

I know one thing I'd like to hear about is the difference in what UV and ozone would do to phosphates. UV, according to what I've read, will break down orthophosphates (?) and make them easier to skim out. However, injecting ozone also increases skimmer efficiency. I'm wondering if you could use either technology since ozone is very reactive. I would think that it should also break down orthophosphates, but I haven't read up on it yet.

Shane

 

[Anonymous]

Shane

UV will break the organic bonds on organic phosphates, releasing ortho-phosphates which can be off-gassed with pressure skimmers. Like a becket.

A lot has changed since people were not able to keep corals. DSB's just allowed people to keep them without understanding their husbandry. Then in turn created a entirely new husbandry based on myth.

 

[Anonymous]

A lot has changed since people were not able to keep corals. DSB's just allowed people to keep them without understanding their husbandry. Then in turn created a entirely new husbandry based on myth.

Lest we fall into polarization, I think it is important to note that there are many who didn't fall into the myth expressed above, but still like sand in their tanks.

 

[RustySnail]

Here are some things that I feel are important to think about. I have no scientific evidence to prove any of these theories; they are only hypotheses. But also let me say that lots of what has been brought to the table by others are strictly hypothetical as well (keep that in mind when you read the various debates).

First, if you look at a system with a DSB, you notice that there is much more 'life' in there than a non-DSB tank. With the abundance of micro-organisms creates a much broader food 'web', and should therefore add stability to a system. When pods and other critters reproduce they provide plankton that is vital to corals, particularly SPS.

You might think of a DSB as a nutrient 'sink'; but I think of it more as a habitat for sandbed oganisms to grow/reproduce. The steady increase in population of organisms in the sandbed is what 'sinks' the free nutrients in your system. The added benefit is the reduction of nitrate via anaerobic conditions. If your sandbed becomes a stable population (fully populated), the uptake of minerals then becomes limited to what the existing creatures can digest and utilize. This would point to the need for 'harvesting' sandbed infauna from time to time via a predator or through direct harvesting (vacuuming) to re-set the population and allow for additional growth and nutrient uptake.
I also have a feeling that a DSB works kinda like your backyard compost heap. In the end everything is reduced to dirt. But that 'dirt' is very fertile. When a DSB 'releases' nutrients it is simply the leaking of nutrients out of nutritive silts. It is not a 'crash' of the system, nor is it a sign that something is wrong. It's just what happens when the garden fertilizer starts to dissolve a bit. So maybe the solution is to stir up the sandbed every year or so and collect out a big portion of the silt. Please note that I am NOT calling this stuff detritus, it is further reduced than that already. Maybe doing portions of the sandbed every few months is the best approach; keeps the likelyhood of the entire sandbed crashing to a minimum. Or maybe addition of a phosphate reduction system would be the way to go (planted fuge, sponge fuge, or the UV breakdown method?). What about using corals that are thought to uptake phosphate directly (some LPS) to achieve this?


But in any case; I don't prescribe to the thought that once a DSB is 'full' it should be removed. Nor do I think that BB is 'better'; it's just a different method (formerly known as a 'true Berlin' system). I feel that a system with a DSB is more 'natural'; by virtue of an established food web foundation.

 

[Anonymous]

Why are you guys always so concerned with fish load and never give a second thought to all this "life" in a DSB?
Why bother with a "so many inches of fish" per gallon rule and not give a second thought to "so many inches of worms" per gallon, "so many inches of pods" per gallon.

Are you convinced that this food web is adding stability?

Then in turn created a entirely new husbandry based on myth.

 

[discocarp]

I think the problem with trying to use other methods (fuge, skimming, etc) to try and handle phosphates that are leaching out of a "full" dsb is that algaes and cyano are very adept at using these phosphates. I think they get to a lot of them before they enter the water column. Even if you could handle them in the water column, you'll still have problems with algae on the sandbed (the "source" of the phosphates in this scenario).

Why not try to deal with the phosphates all along? If all this sinking info is correct, you're basically just putting off dealing with phosphates for awhile. But sooner or later their time will come.

Siphoning and repalcing parts of the DSB on some sort of "regular" basis seems to be the best approach for long term sandbed maintenence rather than just the usually recomended restocking of fauna. The problem is, what is regular? It would depend on so many factors such as feeding that I doubt there's any blanket advice anyone can give on this. Maybe this is why some dsbs fail and others don't. Depending on other husbandry habits, the sinking ability's capacity is reached much quicker in some aquarists tanks than others.

This is all just speculation on my part, take it with a grain of your favorite salt mix.

Peter

 

[Anonymous]

Lest we fall into polarization, I think it is important to note that there are many who didn't fall into the myth expressed above, but still like sand in their tanks.

Righty, most certainly. And at risk of polarizing, unfortunately, Rustysnail’s post is a perfect example of that perpetuated husbandry based on myth.

But also let me say that lots of what has been brought to the table by others are strictly hypothetical as well (keep that in mind when you read the various debates).

If you cared to look, many of the hypotheses you speak of have been supported by peer reviewed, experimental data.

First, if you look at a system with a DSB, you notice that there is much more 'life' in there than a non-DSB tank. With the abundance of micro-organisms creates a much broader food 'web', and should therefore add stability to a system.

Please read my other posts in this thread.

When pods and other critters reproduce they provide plankton that is vital to corals, particularly SPS.

Most of the corals hobbyists label as “SPS” are farmers. They can rely wholly on what their zooxanthellae produce and take up trace amounts of nitrogen and phosphorous from both their symbiont’s metabolism and the water column to translate and transcribe proteins. They also culture bacteria by trapping suspended particulates. None of these “SPS” are adept at capturing the kinds of plankton that spawning and DSB infauna or epifauna would hypothetically be producing.

You might think of a DSB as a nutrient 'sink'; but I think of it more as a habitat for sandbed oganisms to grow/reproduce.

…and regenerate nutrients. There’s just no getting around this.

The steady increase in population of organisms in the sandbed is what 'sinks' the free nutrients in your system.

And what regenerates them into your system.
Also, bacteria would be the only truly efficient biological sinks. They are the only organisms that can get to the necessary populations and they are the bottom of the ladder.

When a DSB 'releases' nutrients it is simply the leaking of nutrients out of nutritive silts.

And you like that idea? In a system where succession to algae who thrive when those nutrient concentrations are present in the slightest could happen, and whose target organisms are poisoned and stunted by them?

Please note that I am NOT calling this stuff detritus, it is further reduced than that already.

No, it’s not. It has nutrients, it has bacterial flock, it’s detritus.

Or maybe addition of a phosphate reduction system would be the way to go (planted fuge, sponge fuge, or the UV breakdown method?)

Regarding the planted fuge idea, again, read my other posts in this thread. UV and offgas are only effective on what they actually contact. Most phosphate exchange takes place in a very localized scenario and involves metabolically expensive enzymes, it’s highly coveted stuff. If it’s fluxing at sand/water interface, you aren’t going to beat the algae. They have a lot of evolution and strategy going for them on this, and they won’t miss a chance to take up any free phosphate. Cyanobacteria and diatoms are the best at this, and all we have to do (and have done) is look at a phytoplankton profile in oligotrophic waters to know this. Although, many hobby tanks have served to support this

What about using corals that are thought to uptake phosphate directly (some LPS) to achieve this?

All scleractinians are capable of this. Based on phosphate uptake kinetics in experiments, most of them rely on it pretty heavily in a closed system. But they only do at concentrations that are limiting. Uptake actually slows to a stop as concentrations rise. And they still regenerate it.

(formerly known as a 'true Berlin' system).

The system I described has never been called that. We call them equal export systems.

 

[discocarp]

One other thought. What is the capacity of "sunk" phosphates to move within the DSB as its mixed by the infauna or other processes? If it moves about, replacing pieces of the dsb may not be super effective. Its like doing constant small water changes to bring nitrate down. Multiple small changes are not very effective when compared with less frequent but larger changes. Would a similar thing apply to phosphates in DSBs with occasional small changes?

Peter

 

[Anonymous]

Detritus decomposes and releases phosphates.

If you leave detritus in your tank to rot it will release phosphates.

You can deal with it after the fact by hooking up algae filters, refugia, any assortment of hamster habitats and monkey pods - or just keep a clean tank and remove it before it rots.

Up to you.

 

[liquid]

UV will break the organic bonds on organic phosphates, releasing ortho-phosphates which can be off-gassed with pressure skimmers. Like a becket.

Will ozone do this as well? I'd be interested in reading any papers you have on either of these aspects.

Shane

 

[Anonymous]

How fast does the UV break the bonds, and how quickly can a skimmer off gas the orthos?