Bare Bottom vs. Sand

[jaredloo]

<a href=showthread.php?s=&postid=9683142#post9683142 target=_blank>Originally posted</a> by cpagego
Baja,

How do pistol shrimp reduce ammonia in the water column? Are you saying that they scavenge detrius which leads to a reduction in NH3?

I think he is saying that he keeps the rock up off the sand bed so that crud doesnt collect under them, and the pistols build burrows under the rock keeping it clear of buildup underneath the rock. As far as I know, pistols don't actually eat detritus.

Is that right baja?

When I had my set up I always had these thick clumps of rock on the ground and it just made a mess underneath. Then I got a couple engineers and they kept it open under the rock.

Next time, I'm going to keep the rock off the bottom as much as possible and have as much of the sand as I can exposed so that I can clean it good.

All in all, DSB I think has the potential of getting bad if not properly cared for, but if it is properly cared for, I think the extra work it requires is worth the benefits it provides. Nothing against BB tanks though. I think it is a great idea, but it lacks some of the characteristics that I desire in a reef tank. A place for sand stars, gobies, pistols, wrasses, nassarius, ceriths, little inverts, etc.

I agree with Aaron, I don't think one way is right or wrong, it just depends on what you want, and what work you are willing to do. And, how much $ you can put in to it. lol.

 

[bajabum]

That is right. They move the sand out from under the rocks were it goes septic. Brittle stars will also do it. You have to provide support under the rock so they won't sink. Water must be able to circulate through the bed. Otherwise you develope pockets of H2SO4 which when disturbed, dump your ph along with a good dose of ammonia or nitrite.
IMO: DSB need life that is not available at the LFS to be succesful without some cleaning. Some of my worms are a foot long. I have clams, welks, brittle stars and other borrowing creatures that allow water to penetrate the sand. Can't till the soil without plows. I have played with sand for years. I avoid fine and very course sand. Fine sand goes septic and can't be disturbed. It will hold a lot of nutrient.
I have all my DSB in seperate tanks that I can isolate from system for maintainance. I am currently changing my macro tanks to include a DSB. I seed my sand with about a gallon of sand from 30' down near rocks. I make sure I get some from a least 6" down and I treat it like a million dollar fish on the way to my tank.

 

[cpagego]

So, then the best way to handle this is to build a scaffold say out of egg crate that elevates the LR off the surface of your tank. The LS is then dispursed under the scaffolding. Treat you LS like a separate filtering entity- chalk full with criters for good turnover and release of H2S04.

Baja,

Are you saying that your main tanks are BB and the DSB is separate like in a fuge, or are you saying that occassionally you will remove sand from your main tank for maintenance such as washing it or tumbling it like lottery balls for cleaning (I thought that it would be a good idea to remove the sand every once in a while, clean it and then return it. Some say change it, but I am not totally certain why). I suppose the Argonite is mostly or partially CaC03 and it does get used up when it reacts with H2S04, but it likely takes years to completely consume the CaCO3 component stored within the Argonite. I likely need to read up more on Argonite and its properties unless you have any enlightening comments.

Curtis

 

[soni]

My next tank will have a remote DSB (9in or so) and a remote mangrove tank with mineral mud. I love the ease of a BB display when it comes to wanting high flow.

I think remote is the way to go.

 

[Elliott]

yeah, I agree soni, though I'm a novice at this. from what I have read with sand storms and trouble with clogging over time, I'm planning to have a remote sand bed tank

 

[jaredloo]

Hmm - remote DSB that's a good idea.

I'm curious too baja, is your display BB and the DSB is remote?

 

[E-A-G-L-E-S]

<a href=showthread.php?s=&postid=9684949#post9684949 target=_blank>Originally posted</a> by bajabum
Otherwise you develope pockets of H2SO4 which when disturbed, dump your ph along with a good dose of ammonia or nitrite.

Just had this happen not six weeks ago and i am just now coming out of it. With no fatalities, new illness, or stn from any my sps, but it was a pain to do that many w.c.'s(every two/three days ~5-10%) and go and buy even more snails for the algae that followed(which is now gone) and the worry about what to now do with my half dsb half ssb(left side) reef

And I have only 7 points of contact from live rock on my sand(although they've sunk down) and run ~61x in tank turnover.

 

[bajabum]

No, I use 1 1/2" to 2" sand in my big tanks, but I clean it for my water changes. BB takes a whole lot of money for machinery to blow the crab out and into a big protien skimmer. Capital cost, heat load and electricity usage would be prohibitive. I would have to scale down for BB. My goal is to come back after a 2 week trip and still have things running. There are no experts up here to fix things while I am gone. They wouldn't even know something is wrong. I am lucky to have a neighbor who understands the importance of not over feeding the few fish I keep.
DSB and sand in my big tanks buys time while I am gone doing my field research. BB is single point failure on tank water movement, protien skimmer and sump pump with no moderating capacity.

 

[E-A-G-L-E-S]

RE: downsize
Maybe not...tunze streams and vortechs are awefully efficient.

 

[bajabum]

To remove a DSB from a tank you can not isolate from lifestock is easy.
Syphon 1/2" to 1" out at a time for water changes. Go down slowly and the bad stuff will disappear as oxygen gets to it. It took me 6 months to pull my 90 down for reorginization. It had a DSP with a rubble reef up to water line on back side. I was even able to retrieve the worms and clams when I was down to the last 2". Everything kept moving down as I removed the top layer.

 

[cpagego]

I took this thread over to the New to the Hobby forum to see what others think. If your interested check it out.

 

[bajabum]

I have about 700 gallons between my two systems of active growing area. A 15 watt pump pumps out of my sump through my protien skimmer. A single rio 300 pumps out of main tank into first support tank which gravity drains to others. Small watt pumps provide water movement in support tanks were needed. In running these systems it has become appearent that problems are more substrate based, not water based.
I cringe at the thought of how much skimmers, and pumps would cost to support 700 gallons.

 

[bajabum]

I added this at the Newbie forum:
I have been running a 700 gallon system with 5 tanks hooked into it. I have determined that substrate controls each tank, not water in the system. I have DSB, SSB and BB (only one) in the system. The BB tank accumulated waste from micro organisims only(amphipods, copepods, shrimp snail, etc). This tank has no fish and has never had food added. Water turn over is about 6x per hour from the system directly to the sump. This tank has developed a massive slime algae and red cyno bloom. All coral frags had to be removed to other tanks in the same system at the onset of the bloom.
All other tanks in the system have some form of sand bed. None of the other tanks show any decline in quality.
The tanks population in micro life is rapidly declining as forms of inedible plant growth out compete there food.
Based on my observations, a BB limits the diversity of life needed to maintain a balanced system capable of absorbing excess nutrients.

 

[cpagego]

Pretty good evidence that DSB is the way to go unless you are going to really pump up the cirrculation and skimming. That is something we can all learn from.

Thanks Baja.

 

[cpagego]

Turns out this issue has a great 50 plus page spread on Advanced Topics. Lots of people are advocating Remote DSB. I will read more, but i wanted to share the link with anyone interested: http://www.reefcentral.com/forums/showthread.php?s=&threadid=595109

 

[ADA33]

^ Thanks great thread.

 

[bajabum]

Took a look at the thread. I found it interesting that they were discussing reaction time to systems in terms of months. If a DSB is going to work, it needs to have a reaction time in hours. Anybody really interested in knowing how to build one that really works just needs to sit down with me for a 10 minitue regurgitation of my masters thesis. The first step is to define what you want the DSB to do. I want mine to procces oranics before they become ammonia/nitrite. I also want it to process phospates. I have always assumed that nitrates/phosphates required conversion to biomass to remove or dilution through water changes.
Is there an organic chemical process I have forgotten that converts nitrates directly to gas that does not store nitrates as biomass?

 

[cpagego]

For our purposes there is only one way to remove Nitrates and that is through conversion to biomass (algael growth) or physical removal. Here is a link to a recent technology that uses catalysts for conversion of nitrates to gas; http://www.sciencedaily.com/releases/1999/01/990105075435.htm

One of these days, we can replace our refugiums with catalysts! Food for thought.

I will have to educate myself more on how a DSB works. I am not sure how a DSB breaks down organic matter without conversion to nitrate. As far as I know, bacteria breaks down the organic material to nitrates and phospates, which then need to be cleared from the system typically through photosynthesis. Nitrates can only be lowered with water changes, removal of organic material (cleaning filters, removing detrious and reducing dead organic material (food and dead animals) and with micro (unfortunate) or macroalgae growth (me likey). I am not sure what else the DSB does. I am not sure how the DSB removes organic material. Perhaps I can read or you can enlighten me.

 

[bajabum]

Well at least we are on the same page. I thought maybe I had forgotten something. A DSB relies on bateria/animals rather than plants/light for removal. Bacteria replace plants as primary food source. They are eaten and up the food chain we go. The advantage to DSB is that it can be in my macro tank with life rock/crushed shell. Also bacteria will react to an increase in nutrients much faster than plants who need a light/dark cycle for optimium growth. A DSB processes 24 hours a day.
The point most often missed is that it is neccesary to remove the nutrients we put in the tank. We skim to much, some plants/animals can not thrive.
A slime algae/cyno tank like I had going yesterday is a great waste procesor. Looks bad though. I added 3" of sand from my DSB tank yesterday to a 1/4 of the tank and the slime is disappearing.
I am currently modifing my big system by adding 4" to 6" sand in the two tanks that grow macro. I add areas of crushed shell to help elavate the amphipod/copepod population. The difference in pest algae/slime production was almost immediate. The first tank was done 2 days ago because I could not keep macro growing in it. The bugs moved from the water column to the sand bed. The macro is growing now.
I am contimplating adding sand to my sumps so I have no areas in the system BB.
For me sand is free, PS are expensive.
Because of my work with flow through porus media, I dont use real fine sand. I want it fine enough food can't fall through the cracks, but porus enough water flows through it. The reaction time of the bed is determined by its porosity. The perfect place for it is in our tanks (all of them). Extras can be added on, but I like the looks of a 4"-6" sand bed with liverock suspended a 1/2" above it and macro growing on it. For kicks, I added a frag rack in the top 2" to start small SPS.
For a dark system, I would do a fluidized bed, but that takes a pump and you have no nutrient export in the bed. My bugs export to my fish reducing how much I have to feed. My 100 gal cube may see food once a week that is not live.

 

[jaredloo]

Yes, you can denitrify, or convert nitrate to gaseous nitrogen in a marine aquarium. My tank does it all the time. The key is a deep, undisturbed bed. The high flow you all are describing through the sand bed stops this from happening because that provides oxygen to the DSB and denitrification only occurs where oxygen is depleted. Read the following discourse on denitrification.

I always get nitrogen bubbles forming in the DSB that creep out and leave the tank via evap.

Denitrification is the process of reducing nitrate and nitrite, highly oxidised forms of nitrogen available for consumption by a many groups of organisms, into gaseous nitrogen, which is far less accessible to life forms but makes up the bulk of our atmosphere. It can be thought of as the opposite of nitrogen fixation, which converts gaseous nitrogen into a more biologically available form. The process is performed by heterotrophic bacteria (such as Paracoccus denitrificans, Thiobacillus denitrificans, and various pseudomonads) from all main proteolytic groups. Denitrification and nitrification are parts of the nitrogen cycle.

Denitrification takes place under special conditions in both terrestrial and marine ecosystems. In general, it occurs when oxygen (which is a more favourable electron acceptor) is depleted, and bacteria turn to nitrate in order to respire organic matter. Because our atmosphere is rich with oxygen, denitrification only takes place in some soils and groundwater, wetlands, poorly ventilated corners of the ocean, and in seafloor sediments.

Denitrification proceeds through some combination of the following steps:

nitrate ¨ nitrite ¨ nitric oxide ¨ nitrous oxide ¨ dinitrogen gas
Or expressed as a redox reaction:

2NO3- + 10e- + 12H+ ¨ N2 + 6H2O
Denitrification is the second step in the nitrification-denitrification process, the conventional way to remove nitrogen from sewage and municipal wastewater. It is also an instrumental process in riparian zones for the removal of excess nitrate from groundwater contaminated by fertiliser use.

Direct reduction from nitrate to ammonium (a process known as dissimilatory nitrate reduction to ammonium or DNRA) is also possible for organisms that have the nrf-gene. This is less common than denitrification in most ecosystems as a means of nitrate reduction.

Reduction under anoxic conditions can also occur through process called anaerobic ammonia oxidation (Anammox), this reaction is expressed as the following:

NH4+ + 2NO3- ¨ N2 + 2H2O
In some wastewater treatment plants, small amounts of methanol is added to the wastewater to provide a carbon source for the denitrification bacteria.