Pros vs Cons: Deep Sand Bed vs Shallow Sand Bed

[vlangel]

Goodness I'm getting so confused... First you hear that a DSB should be no less than 4" and no more than 6" now 12"?! Aarrgh :::pulls hair out::::

Don't sweat it too much. If you keep it at the 4-6" range you will be fine. My boss put a lot of them in, ( and he tragically died in '07 ) and most of those sand beds are still in operation.

 

[Akida17th]

Thanks! I haven't done a water change in 5 months... And you DO NOT touch the sand. You don't siphon it or stir it or anything.
Think of the sand bed as being made of several layers. It has to be deep Bc at the very bottom where there is very little oxygen is where the denitrifying bacteria live.
That is also why it's important to use only the super fine sugar fine sand. For the maximum density to block oxygen.
And the layers cannot be mixed, each inch has different micro organisms and bacteria. If you take a net handle and push it all the way to the bottom you will create a mass death in the layers and cause a hydrogen sulfate pocket.
Then if you disturb that, it will release that gas into the tank and kill everything.
But if left alone the bacteria will process the death over the course of a couple months and the gas will be gone and no longer a threat.
So don't mess with it!

You can't mix types of sand when creating a DSB? For example, if I wanted to use Caribsea Seaflor for the first 3" and then Oolite for the next 2" I would run into issues?

 

[jgraz]

There is no reason you can't mix. Though you would want the finest sand at the bottom and coarser at top

 

[Acro Man]

https://m.youtube.com/watch?v=h39VK-tNK30

Watch this video!! This has parts about DSB and it's well explained!!!
DSB is the way to go! Main reason keeps P04 and N03 undetectable, it's a filtration and is a home for micro organisms that are a huge benefit for filtration and food even trace of elements! One reason people don't go DSB is looks and scared of failures ! Now one mistake people do is disturb sand, worse mistake to do with any sand bed, maybe you been doing it but it's gonna catch you sooner or later. But with me I like to have someone that benefits my tank then not. Plus I think it looks better plus save money, buying media and etc!

 

[Frozn]

I feel a DSB offers a lot of benefits. However i would never keep one as part of the display or fuge. But feel a remote (bucket) sandbed is actually the best route if choosing to do so. Having that depth of sand is when it's beneficial qualities start to shine such as lowno oxygenated areas in the sand

 

[jzaso]

I,m a firm believer in dsb, the denitification and micro fauna the dsb provides are essential to long term tank health-what you do not want do is mix the stratified bed no big sandsifters or borrowing crust,fish- no mixing of anerobic and aerobic layers that is when problems start-also the finer the substrate the better no accumulation detritus- oolitic aragonite 4"/6" deep good flow across bed- all pro no cons-most public aquaria use a dsb as primary denitrification.
Anthony Calfo has some good reading on dsb-I have been running dsb,s for years my oldest bed is 11yrs and the substrate looks like I just put it in,

 

[Randy Holmes-Farley Verified Community Expert]

Watch this video!! This has parts about DSB and it's well explained!!!
DSB is the way to go! Main reason keeps P04 and N03 undetectable,

As Julian stated in the video, sand beds, deep or shallow, do not do much that is useful for phosphate. :)

 

[s2nhle]

Great thread. For me I have BB and minimal amount of lived rock to keep the total weight less.

 

[Akida17th]

Can you start a dsb with dry rock? I have a 93g cube I'm doing a dsb on but I want dry rock. Can I seed the dsb with dry rock or do you have no choice but to do live rock

 

[jzaso]

You need to seed the new system- water /sand/ lr/from a established system to introduce the micro fauna into the new system to start the process and it takes a while (months )for the dsb to be productive

 

[Akida17th]

You need to seed the new system- water /sand/ lr/from a established system to introduce the micro fauna into the new system to start the process and it takes a while (months )for the dsb to be productive

The live rock part can be accomplished but the water/sand cannot. Can dry rock be used as stated above with some mature live rock and aragonite to seed the dsb? I will be cycling the tank anyways so there is no rush. If anyone has done a DSB, which type of sand usually works best or you have had success with. Is there a large difference between live sand and aragonite sand? Right now I'm in the process of my build and am trying to figure which sand to utilize for the DSB which will be in 93g display. Purchased a 24g 24x15x15 refugium sump today and recently purchased a Vertex Omega 150. Just trying to figure out the sand situation and rock situation. I have 75lbs in my 55g but the tank has been seriously hit with cyano and I don't want to transfer any of that over. I also have seen you can purchase dsb critters from online stores like ipsf.com

 

[jzaso]

Yes a little live rock with your base rock will help seed the dsb bio-diversity is key to a productive dsb if you could find some hobbyist to hit up for a cup of sump/dt sand /water that will speed things up a bit. As far as the live sand stuff little on the fence about its worth-I use dead" sand- particulate size is of importance the finer the better less likley to trap detrius I use a oolite aragonite sand (my spelling horrible) .5mm or less @4"min depth 5"/"6 is better aragonite sand offers buffering trace elements and a nice home for the benthic critters-

 

[omykiss001]

The process of denitrification is the whole point of the DSB. We are trying to build a habitat that is low or absent of oxygen. The microbes that can live here are facultative aerobes, meaning if they have it available they will use O2 to respire just like you do. However these bugs can also use nitrate and strip the oxygen from that molecule to respire and make nitrogen gas as a waste product thus reducing the nutrients available for other plant life. The nice thing is nitrogen gas is very inert and will either be burped as a gas bubble or will dissolve into the water and then be released during the gas exchange process. For those who remember your chemistry it works like this; using the enzyme nitrogen reductase the oxygen is stripped off the nitrogen and combined with 2 protons via the electron transport chain in the bacterial cell membrane which allows the microbe to make energy to grow and reproduce and make water and nitrogen gas as waste products 2 NO3- + 10 e- + 12 H+ → N2 + 6 H2O. This is a simplistic view as this is just how they get the oxygen they need to dump electrons to get energy, they also release CO2 and require a carbon source like you do think sugars and carbohydrates. Thus the reason you don't want to disturb the environment as this will mix oxygen in and these bugs will just use it rather than stripping it from nitrate.

The true anaerobes like the sulfur reducing bacteria take sulfur containing molecules and turn them to hydrogen sulfide and require no oxygen to respire and make energy and tend to be obligatory anaerobes meaning never use oxygen to respire. Here too the hydrogen sulfide gas will diffuse out and be exchanged to the external environment via gas exchange. It is highly unlikely or near impossible to have a state where the H2S would ever build up in the substrate and then be released as the hypothesized gas bomb. As others have stated you would smell this long before it became toxic, same compound they put in natural gas in ppb or ppt (trillion) to alert you to a gas leak, takes very little to smell it. While true a DSB will have a true anaerobic environment and a population of sulfur bacteria they will more than likely be limited by the fact nutrients have to make it down to this layer and will limit the population size. Things have to be very wrong to get a bloom of these bugs and would be very noticeable long before this stage as the aerobic bugs would bloom so big to use all the O2 to make an environment large enough to host that large a population of sulfur bugs to produce that much H2S in a short time period to build up before being able to be released slowly to the environment.

In contrast there are also bugs that can take molecular nitrogen and fix it into nitrate, the legumes like beans harbor these bacteria in root nodules and thus can live in very nutrient poor soils.

I have been debating having a DSB in the build I'm getting ready to do, but for me it's not about if it will work or if it is good, it's about the critters I want to keep and some of the stars and snails that appeal to me by nature will disturb the hypoxia environment or eat the detritivores that help the DSB to function effectively. Thus I've been thinking of having a ATS (algae turf scrubber) to remove nitrate and phosphate without using chemical scrubbers or dosing, however the DSB still holds much interest to me and I'm not settled on not having one.

My .02

 

[Nano sapiens]

Never kept a DSB, so can't comment there.

But 30+ years with SSBs and they work just fine as long as detritus is regularly removed.

Although SSBs are known generally as aerobic environments, the reality is that they support both aerobic and anerobic bacterial poulations. The anearobic bactera exist in the sand grains' micro-pores and are in close proximity to aerobic species. Makes for very effficient nitrification/denitrification as long as flow is not impeded by sediment/detritus buildup. When folks have SSBs that are rarely, if ever, disturbed...that's when water quality problems develop over time.

 

[that Reef Guy]

I think that you should change the Poll so I can Vote NO Sand Bed.

Sand takes forever to clean and holds in Phosphate and Leaches it Back Out.

I will never use Sand Again after seeing how great and and easy to clean my Frag Tank is.

All New Future Tanks will be Barebottom.

Is it possible to change a Poll after it is made?

 

[Randy Holmes-Farley Verified Community Expert]

I think that you should change the Poll so I can Vote NO Sand Bed.

Sand takes forever to clean and holds in Phosphate and Leaches it Back Out.

I will never use Sand Again after seeing how great and and easy to clean my Frag Tank is.

All New Future Tanks will be Barebottom.

Is it possible to change a Poll after it is made?

I agree that detritus accumulation can be a concern, but I've just never understood how the phosphate binding is any concern.

Why does it worry you?

 

[brandon429]

Randy glad you chimed in, I had been thinking that as well here's why, pls correct

if the detritus is degrading next to any bindable calcium carbonate structure then the rocks and or the sand might uptake the po4 and then it can be re leached later through bacterial means...like live rocks that may be a leaking source of po4

Ive never had that occur in my tanks, and they ran unskimmed with a dsb for years, the live rock may be leaking p04 but I can't tell because ive no algae problems. I dont even know if the phosphate binding directly occurs in substrates, but its the common things said online nowadays, implicit in many a problem algae thread apparently.

perhaps they were also just referring to physical diapering where the sb holds in whole proteins that could have been otherwise removed or rendered neutral. maybe it leaks just because its held there ?

 

[hart24601]

With other nutrient exportation available I will never run a DSB, I don't see the point and hear way too many bad things. I don't run any sand at all now after seeing what was in my old sand bed that I couldn't reach to clean - even with sand clean up crew is was nasty nasty stuff. If I was going to run one with would be off the sump where I could close valves and change the sand every few years, but I am not an expert on that. To those using them with great results that is awesome, but not for me.

 

[brandon429]

I would not use one in a large tank for sure. My tank is so small I can set it whole in my sink, and pour 20x tank volume through it -hard- which mixes up the sb and ejects all the waste. my tank is adapted to it, has been about 10x now, its like a tidal flushing. no fish...coral and inverts can hang ok w this. Only due to abnormally easy access to the bed is why I have one. I like the looks always of sb vs no sb, but for waste issues the cleaner one wins out in big tanks at least.

Technically, any sb that is regularly cleaned and doesnt store up waste is the same as not having one, if, there's isn't a side uptake issue of phosphate can't wait to see what Randy thinks/

 

[Randy Holmes-Farley Verified Community Expert]

Randy glad you chimed in, I had been thinking that as well here's why, pls correct

if the detritus is degrading next to any bindable calcium carbonate structure then the rocks and or the sand might uptake the po4 and then it can be re leached later through bacterial means...like live rocks that may be a leaking source of po4

Ive never had that occur in my tanks, and they ran unskimmed with a dsb for years, the live rock may be leaking p04 but I can't tell because ive no algae problems. I dont even know if the phosphate binding directly occurs in substrates, but its the common things said online nowadays, implicit in many a problem algae thread apparently.

perhaps they were also just referring to physical diapering where the sb holds in whole proteins that could have been otherwise removed or rendered neutral. maybe it leaks just because its held there ?

I agreed that detritus may be an issue, whether the phosphate is immediately released or slowly released. It doesn't concern me and I let detritus accumulate forever in my sumps and refugia, but folks who want ULNS systems might best remove it. Preventing accumulation may be easier in a no sand situation.

All calcium carbonate surfaces in the tank (rock, sand, and exposed coral skeletons) will bind some phosphate from the water. The amount bound is in equilibrium with the phosphate concentration in the water. It is essentially a reservoir of unavailable phosphate that would be released if the phosphate concentration in the water got lower than the concentration where it initially bound. It won't come off and suddenly make the water phosphate concentration higher than when the phosphate initially bound, because it would bind again if that were the case.

So any time you look to drive down (not maintain, but actually lower) the phosphate concentration, this reservoir will need to be depleted. Likewise, it acts as a buffer against rises in phosphate because it binds more as P rises. In effect, it stabilizes the phosphate concentration and makes it slower to move up or down.

So I see little to be concerned with that some phosphate binds directly to the sand surfaces. :)