Limitations of DSB's

[Spanky]

>How come the success of some long term sandbed tanks?<

And plenums too! Mostly plenum systems that I know of. Because of all the different variables. what material is used and how they are maintained, what animals, what etc etc. Some people know what they are doing. DSB's will, again, hide a multitude of sins for a beginner though.

>If sandbeds are so good for ones tank, how come they stink so bad on removal, they make one regurgitate? <

For exactly the same reason that well water stinks when you first turn on the faucet.

Somehow you guys got back on metals again. I'm just trying to make you aware of detritus and bacteria. BUT, even if you're just worried about metals think about this.

Every surface in that tank is covered by bacteria, including any CaCo3. Any metals that are able to bind to the carbonate will be consumed and freed up by bacteria. Bacteria is the driving force for these systems on all levels. Much of nitrogen and phosphorous, and many heavy metals, are incorporated into the biomass of the new bacterial cells. (that's why so many corals farm their own, they are nutritious!! well that and the fact that most corals aren't good at actually catching live food at all)

So stop worrying about metals and replacing your rocks and sand beds. It's organics that are going to give you the hardest problems anyway.
Now think, what can you remove from your tank that will take care of organics and the bacteria that are happy to live in them? I'll give you a hint, it's what most corals feed on.

[Spanky]

>How come the success of some long term sandbed tanks?<

Because all tanks and tank owners are different! LOL

[mojoreef]

See that is going to be the toughest one for DSB users to grasp. They all believe that the DSB will process everything to a gasious state and they will not understand the concept of end product diterus. They believe that they have a one shot do it all filtration method, that takes the crap and turns it into benefical gas. That is they way it has been sold for years. You cant blame them.

Mike

[Green Chromis]

Jerel thanks, now it,s time for a beer and a Cabo Wabo shot.

[mojoreef]

Just to add to Spankies statement in regards to the bacteria and the compounds that they thrive in or use for bacterial action. Just think if you wanted to create an enviroment that is skewed for the the growth of bacteria, what would you make ??? a dsb. Now couple this with the fact that you have to feed your tanks inhabitants thus adding more metals/organics and such and you have created a cornacopia for this bacteria. So what happens to it. Well some enter the food chain, corals eating the bacteria, worms and such eating it and its biofilm, then they get eaten by a fish or a crab and so on and so on. As this stuff progresses up the food chain the things that eat it add all the nasties to thier biomass. So its not only the fact that the DSB is slowly filling with it, but so are your inhabitants.


mike

[Spanky]

Mike,

Maybe it's because people are familiar with organic detritus and not inorganic detritus. The purpose of any system of this type is the breakdown of these organics to their lowest common denominator (into utilisable nutrient), a process known as remineralisation.

This doesn't have to be studied in a reef tank or a DSB, the process is exactly the same in a estuary.

Most of what you guys are worried about your going to find locked up in detritus (either organic or inorganic) (directly or indirectly).

[cyberchef]

Originally posted by Spanky

Now think, what can you remove from your tank that will take care of organics and the bacteria that are happy to live in them? I'll give you a hint, it's what most corals feed on.

Bacterial cells and soluable nutrients

[cyberchef]

Originally posted by kestrel

As Don was saying, he is striving for a fully closed eco-system. If it is truly a closed system, then everything gets recycled. Nothing new is added. Others are saying, "well I am only adding blender mush, and I try to remove the same amount through skimming, water changes, harvesting macroalgae, etc, etc." Part of the problem that is being alluded to, but not clearly stated, it seems, is the inclusion of persistent bioaccumulated toxins (PBTs), such as mercury and lead (Easy examples, but there are lots of metals, and organics that fall into this category).

Actually I said

I've been striving to "develop" a self sustaining ecosystem. my whole reason for using refugiums in the first place. I don't use them for nutrient export, but for nutrient import instead in the form of the production of live food.

There is a big difference between a "self sustaining ecosystem" and a "Closed Ecosystem". I've tried to intentionally set up my system so that it has the capabilities to produce the majority of it's needed "food" (be self sustaining). I still do feed, just not often, and I still do water changes (albeit not as often as i should... ) but if everything is fine, water parameters and inhabitants, then I don't necessarily feel there is a need to do a water change.

Water changes are a good way to replace trace elements that our systems need without using additives, they are also a great way to remove excess nutrients (nitrates and ammonia) in the water column from over feeding. Since I try not to overfeed, I've found that I very rarely have a problem with high levels of nutrients in the water column.

I found this to be proven true about 2 months ago. I made the mistake of getting a small Blue Throat Trigger. Beautiful fish, but it was a pig, I had to start feeding every other day and even daily at one point. He lasted a week before he went back to the LFS, because I realized I had made a mistake for more reasons than 1. He was too big for the layout of my system, he needed to be fed a lot, and he liked to dig (this was the final straw) down into my DSB (that is over my plenum). I found my nutrient levels in the water column were rising (suddenly I was getting an actual reading for nitrates and I was getting algae blooms) so I found myself having to do more larger water changes, more frequently, in order to keep the nitrate levels at what I felt was acceptable (as close to 0 as I can get them).

This disturbance of the DSB aslo released "nutrients" that were trapped in it's layers causing more algae blooms. Of course the algaes were taking up the nutrients so even tho I was getting a 0 reading I still knew there was a problem. Having to tear the tank apart in order to get him out also showed me how much detritous and such was trapped in my LR and the top layers of my SB, despite all that I had done to physically remove it, ie: blowing it out of the LR and filtering it out with filter media in the sump). When I put it all back together I left about 1/4 of the LR out and placed it in another tank. I also had to add more substrate to replace what had been shifted and to fill in the ravines the trigger had created. Guess what, disturbed SB coupled with excessive feeding, coupled with new substrate equals high nutrient levels in the water column which equals CYCLE and more algae blooms. My shrooms and polyps have loved it, they've taken off (need to be fragged).

Despite all of the attempts at removal of the detritous, it's amazing how much is still able to remain trapped in the LR and SB. I'm planning on getting a hang on canister filter (magnum 350) just so that once or twice a months I can set it up and see just how much detritous I can stir up and then filter out. Even with a very lite feeding regimen, there is still far more excess nutrients in my system than the "ecosystem" can process. Which is why my system is still able to produce plenty of micro/macro fauna to "feed" the system.

It's this detritous and the bacteria that it feeds that is the greatest problem.

Any time ANY food from outside the system is added to the "closed" system, very low levels of these PBTs are added to the system.

As other animals consume the food, their bodies store these PBTs (thus bioaccumulating). Then when that organism dies or is eaten by another, it returns ALL of the PBTs to the food chain, but this time in slightly higher levels than anything that the now-dead organism had consumed. Repeat. Repeat. Repeat...

Now you have PBTs working through the system at levels that are approaching toxic affects. Check the history of Peregrine falcons and ohter birds of prey and the use of DDT.

The reason the closed system that Don is advocating would be an improvement is that no PBTs would be added. Although it also stands to reason that as the PBTs move up the food chain, when a large organism (fish) dies (including all of its accumulated toxins) we remove it from the system, so that it doesn't create a "spike."

Until the biomass is decomposed to it's most basic form and then consumed and freed by bacteria, it's still not a problem.

[i] originally posted by Spanky [i]
The purpose of any system of this type is the breakdown of these organics to their lowest common denominator (into utilisable nutrient), a process known as remineralisation.

It's the soluable nutrients created by the remineralisation that goes back to fueling the growth of bacteria that feeds on the detritous.

Ok Jerel, correct me please if I've totally screwed this up.

[SPC]

Originally posted by Spanky
Most of what you guys are worried about your going to find locked up in detritus (either organic or inorganic) (directly or indirectly).

Good morning Jerel,
So your ascertain is that the majority of the inorganic detrius (I presume our heavy metals are included in this) are removed through the process of skimming?
Steve

[SPC]

Originally posted by Spanky
Every surface in that tank is covered by bacteria, including any CaCo3. Any metals that are able to bind to the carbonate will be consumed and freed up by bacteria. Bacteria is the driving force for these systems on all levels. Much of nitrogen and phosphorous, and many heavy metals, are incorporated into the biomass of the new bacterial cells. (that's why so many corals farm their own, they are nutritious!! well that and the fact that most corals aren't good at actually catching live food at all)

So stop worrying about metals and replacing your rocks and sand beds. It's organics that are going to give you the hardest problems anyway.
Now think, what can you remove from your tank that will take care of organics and the bacteria that are happy to live in them? I'll give you a hint, it's what most corals feed on.

Jerel,
Another question please sir , if the bacteria covers the sand grains, then how can this bacteria be removed without taking out the sand or replacing it with new sand? I mean, I wouldn't think you could just vacuum out this bacteria.
Steve

[Spanky]

Don

That's a good example of what Chris was referring to. Complete with algae bloom.

>>So your ascertain is that the majority of the inorganic detrius (I presume our heavy metals are included in this) are removed through the process of skimming?

You're going to loose a pretty good bit of it that way. At least it's going to remove it on a fairly consistent level. Problem is, in closed systems you don't have that much up in the water column.

>>Another question please sir , if the bacteria covers the sand grains, then how can this bacteria be removed without taking out the sand or replacing it with new sand? I mean, I wouldn't think you could just vacuum out this bacteria.

Bacteria will be on and in your sand grains. The bulk of it will be on detritus between the sand grains though. That you can vacuum out. Just like a system with no sand produces detritus just from the rocks. Difference is, that you can see. In this case, it's just in the DSB and you can't see it.

[Spanky]

With what time I've had today, I looked as best I could. This is all I was able to find on the internet. I know it's fresh water but it's close enough I guess.

http://www.esf.edu/efb/schulz/Limnology/bacteria.html

b) Bacteria and algae compete for phosphorus and inorganic nutrients (bacteria are usually better competitors),

c. UV light can help to break down DOC to more usable forms, but also directly inhibits bacterial growth

2. Bacteria can compete with algae for inorganic nutrients, and thus may actually be a 'sink' rather than a remineralization source

It's a shame there's not more available on the internet. Here's a favorite that's not available as far as I can tell.

Nixon, S.W. 1981. Remineralization and nutrient cycling in coastal marine ecosystems. Pp. 111-138 in B.J. Neilson & L.E. Cronin (eds.) Estuaries and Nutrients. Humana, NJ.

[Spanky]

I know everyone's worried about all that CaCo3 in your tanks, About coppers, zinc, metals in general, About having to replace your sand and LR because of metal binding and complexing to the CaCo3. Metals are not going to be your problem. Metals are going to be complexed by bacteria, plants, organics, etc. - mostly bacteria. Even if they find a way to get by the bacteria and get to the carbonate first, bacteria are going to get on them, incorporate them.

DSB's have a wonderful use, processing organics all the way through to to off-gas. I believe the big confusion comes from people thinking these eco / micro-eco systems somehow process metals and in-organics to this state also. Nitrogen off gassing is one thing; copper, lead, mercury, etc off gassing would be something else entirely. Fortunately, the easiest place to find these is in detritus. Either directly bound to organic compounds or complexed in bacteria associated with these organics in detritus.

Cliffs notes version:

DSB's process nitrogen all the way through to gas. Not metals. Metals are complexed by bacteria first, organics (usually in conjunction with bacteria again), then plants - usually in that order.
If people are worried about organics and metals, then remove detritus. That's where all their problems are going to be. Not locked up in CaCo3, but in organics and bacteria.

[mojoreef]

Spanky I just want to congradulate you. This is the first time since I have known you that you have spoken common English in a thread that I can actually understand, lol you da man.

I think we might be turning him into a hobbest. Chris your next.


Mike

[Minnreefer]

One word

Thanks