LR, LS and Old Tank Syndrome

[SquishyFish]

It was recently brought up on another thread (that I didnt want to hijack) That changing out the Lr as suggested by Dr. Ron stems from his research on OTS. Reefrunner stated that more and more people are pulling their DSB's and going back to bare bottom tanks.

I was under the impression that proper aeration and shifting by a thriving infauna population would sustain a DSB and keep it from suffering from OTS. Is this not the case?

I am moving in about 3 months and that would be the best time to pull the DBS if I am going to do so. (actually its not but about 2inches deep). How drastically would this effect the filtration of the tank?

I am also considering simply moving the DSB to the sump.

Squishy

 

[SquishyFish]

This is an excerpt from Dr. Ron's article.

Fortunately, prevention of sediment clumping and the simultaneous maintenance of optimal biological filter operation is easily done by the establishment of a healthy and diverse sediment dwelling fauna, or "infauna." The infauna, so-called as the FAUNA lives IN the sediments, is a very diverse array group of wonder-working organisms. Unfortunately, they are small, and are not particularly attractive. But they do most of the work in keeping any reef tank functional.

The infauna are "the clean-up crew" and the "reef-janitorial" staff, and the array found in a successful tank may be DIVERSE! More than 200 different species commonly are found living in a mature sand bed. These include many types of flatworms, round worms, dozens of species of bristle worms, small snails, brittle stars, small sea cucumbers, protozoans, and many types of small crustaceans. The total populations may be immense.

What does this diverse and abundant array of critters do for and in the sand bed? Well, some will eat excess food, detritus, or algae. In doing so, they utilize it, and excrete part of it as waste. In turn, bacteria utilize that, and thus the infauna help keep the biological filter going. Additionally, many infaunal animals burrow ingesting some sediments as they go. They digest the microorganisms off of them, opening space for bacteria to grow.

By moving through sediments, the animals jostle and move the particles. Not much, just a little tiny bit. It has been estimated that each day each small organism moves about 10 to 100 cubic millimeter of sediment. Multiplying this tiny average amount of jostling by the number of animals in the tank gives the total amount of disturbance. With this amount of jostling and sediment eating, sediment clumping the sediments will simply not occur.

 

[reefrunner69]

I'm copying my reply in the other thread over here.

I think the thinking now is that they are very big sinks. They will hold the heavy metals and phosphors for only so long and then they crash. I also don't see how aerating or sifting would remove heavy metals from sand or rock.

I am also not saying I subscribe to the heavy metals theory, simply pointing out that might be a reason why Fenner would recommend replacing some rock every so often. I do find logic in the DSB being a sink. All the detritus and waste processed by the sand has an end product, not all of that end product is nitrgen, this is sunk into the DSB, over time the sulfide layer creeps ever so slowly upwards until there are problems all over the place.

Here are a couple of threads where people explain, and understand the science much better than I do.

http://www.aquariumadvice.com/viewtopic.php?t=1494

and

http://www.reefsanctuary.com/forums/showthread.php?s=&threadid=482

 

[Guest]

So does this mean that in the long run DSB aren't really worth it then? I mean I never really heard of any of these problems in bare, shallow, or even cc. high nitrates vs. ots? which is better?

 

[reefrunner69]

IMO, a DSB's years are numbered, how long? Alot will depend on set up, bioload (I would not cycle rock in a new DSB), and maintenance. Rob Toonen had a DSB set up for over 15 years, that tank had a very low bioload and an expert in the field maintaining it, I don't think we can necessarily expect the same from ours. Things to look at when choosing a DSB...

1) Am I going to upgrade in the next 3-5 years (many people will upgrade or down grade in a short space of time)
2) Am I willing to rip that sucker out and start over with something else in the next 3-5 years
3) Am I willing to research everything I can on how to set up (properly) and maintain a DSB

I know people that are ripping theirs out, I know people that want to, but have huge established tanks and are putting it off simply cause of the nightmare it will present to pull it out. I know people that are riding the fence and I know people that are starting with DSB's right now even knowing the experiences of others. It is a decision you have to make for your tank, just make an informed decision, don't jump on any bandwagon.

 

[Biggen]

I am a believer is DSB's, but only IF (and this is a big IF) they are setup properly to begin with. From many of the problems with DSB's I have read about, people either used the wrong grain size sand, didn't have the SB deep enough, didn't seed the bed with infauna, housed livestock that ate the infauna living in the bed and/or housed livestock that disturbed the SB to the point of collapse, overstocked the tank, etc...

The list goes on and on. Dr. Ron has specifically stated many times that it is not possible for a DSB to "become a sink". The waste has to go somewhere...

As you can see, the views differ on the topic. I have a DSB and so far, have had zero problems with it. I have only had it running for 8 months and hope to have it for years to come. Only time will tell.

 

[SquishyFish]

That was a great read...as much as I could get through. My eyes started to cross after a while.

This is what I am gathering.

Food in...fish eat.

Fish use 10% and poop 90% out. This patter continues all the way down through the crabs and such to the bacteria.

Aerobic bacteria which are bacteria that have access to oxygen break down the Ammonia and nitrites.

The lower levels of the DSB break down the nitrates in a gas that is released back into the air.

The problem is that metals are not bound together untill you reach depths below 5inches minimum. That means that most of us have alot of metals going in and very little going out.

I'll finish this later...time to go home!

 

[steve-s]

I copied this from an earlier post. It's slightly out of context but I think you'll get the jist

A DSB is not the only way to complete the nitrogen cycle nor is an anaerobic set up the only way to do it. There is one type of bacteria that lives in both anaerobic as well as anoxic regions of the tank called facultative anaerobes. These facultative anaerobes can go back and forth between oxygen void (anaerobic) conditions as well as reduced O2 (anoxic) conditions. The anoxic areas are primarily the live rock and sand areas beneath the rock where water flow is not as easily accessed thereby feeding of O2 is much less available.

The bacteria in each case has a different feeding process. In an anoxic state, the bacteria feed primarily on available O2 and nitrates which are in turn converted to CO2 and nitrogen. In an anaerobic state these bacteria must consume other elements that that contain oxygen such as nitrates and sugars to survive. The conversion from nitrate is however not the same. The anaerobic bacteria instead produce the same CO2 and nitrogen but as well give off hydrogen sulphides and methane gas.

Providing there is sufficient amounts of live rock and animals specifically introduced to reduce waste matter, as little as 1" of sand can and will be enough to allow nitrogen to form.

If the tank is set up properly, not overcrowded and maintained regularly you can have a successful tank. It really comes down to how you plan the tank as a functioning ecosystem and how mindful you are of what goes into it.

Cheers
Steve