Are Deep Sand Beds really a thing of the past?

[Kitjo]

Almost 20 years ago, when I was first going to start a reef tank, my plan was to do a deep sand bed. I loved the idea that deep sand beds (without sand sifting creatures) were an integrated part of the reef ecosystem. It appeared that there were a lot of people who had them for years and years.

It appears now that the hobby has moved away from this.

Is this because deep sand beds do not work?
Is this because deep sand beds are too risky?
Is this because deep sand beds have been replaced by something better?
Is this because deep sand beds have just shifted in popularity?

Is there anyone still starting new tanks with deep sand beds?

Thanks!

 

[dmsc2fs]

I am no expert but I did a few searches on this topic. They work, but they are risky. They can trap gasses that when released can kill the entire livestock. Many people have had success with them from what I have read. When it is disturbed is when the problems appear. They have been replaced by a number of different options including Algae reactors and other devices that address nitrates such as the Nitrate destroyer.

 

[Rjramos]

Deep sand beds worked in reducing nitrates very efficiently. The biggest deterrent to these systems were the amount of space required to put one in place. No one wanted the required +4 inches in their display and it wasn’t easy to accommodate under the cabinet either. Not only depth but also surface area. The most important part of these systems was the anoxic layer. Nothing ever replaced this, just we found other ways to reduce nutrients. I personally went the miracle mud and growing caulerpa algaes route. The mud works in as little as 1” because the smaller particles provide the necessary anoxic conditions.
Here’s Bob Goemans booklet on the subject, copyright 2000.

 

[Dan_P]

Almost 20 years ago, when I was first going to start a reef tank, my plan was to do a deep sand bed. I loved the idea that deep sand beds (without sand sifting creatures) were an integrated part of the reef ecosystem. It appeared that there were a lot of people who had them for years and years.

It appears now that the hobby has moved away from this.

Is this because deep sand beds do not work?
Is this because deep sand beds are too risky?
Is this because deep sand beds have been replaced by something better?
Is this because deep sand beds have just shifted in popularity?

Is there anyone still starting new tanks with deep sand beds?

Thanks!

Your questions are great. They would be the ones I would ask concerning any technique or technology in this hobby. Here’s my take on the subject.

Most choices in this hobby probably follow what’s popular AND what do I like to do. I give this the heaviest influence on deciding on a sand bed question.

Does it work? If you mean denitrification, NO3 to N2, probably.

Risk is still a decision driver and still debated to this day. I am not total convinced of the level of risk but it certainly scares off people. Anecdotal data on this subject is all we have.

Is there something better? The fairest answer is there are more options for reducing a nitrate concentration today. No one has actually run a controlled experiment that I know of comparing the various ways to control nitrate concentration. Much anecdotal data and strong feelings about the various methods.

 

[MnFish1]

Almost 20 years ago, when I was first going to start a reef tank, my plan was to do a deep sand bed. I loved the idea that deep sand beds (without sand sifting creatures) were an integrated part of the reef ecosystem. It appeared that there were a lot of people who had them for years and years.

It appears now that the hobby has moved away from this.

Is this because deep sand beds do not work?
Is this because deep sand beds are too risky?
Is this because deep sand beds have been replaced by something better?
Is this because deep sand beds have just shifted in popularity?

Is there anyone still starting new tanks with deep sand beds?

Thanks!

It would be interesting if you made this a 'poll'.

In the past I used one. (considered good for nitrate reduction, etc) - IMHO - they are replaced by other mechanisms - and IMHO - look ugly in a display tank. lots of people though - still use them in refugia

 

[HuduVudu]

I have used plenums for 20 years.

They work, they are not risky, but they have caveats.

Implementation is everything.

Here is what I have learned about them.

Do NOT implement them in the main DT. The reason why is that the rock work that sits on top of them creates "shadows" this can impede proper movement through the bed. I have taken to implementing them in 6" PVC tubing. This helps with a couple of things. It ensures that the don't have things sitting on them. It gets them out of the DT, and finally it ensures their longevity. These things work best in the long term. There have been a bunch of scares about the plenums/deep sand bed re-leeching nitrates. This simply does not happen.

Many people want immediate reduction of nitrate. They will not do this. They take time to get going. There are implementation techniques that will make this process go faster but you are looking at at least 4 months to get one going. Also if more nitrate is being produced than they can consume then they won't reduce all of the nitrate. They have a capacity and that often gets lost on a lot of people. Since they are biological there is a ramp up and ramp down period. Meaning they slow the change of of nitrates. This is really helpful for someone trying to achieve balance, but totally frustrating for someone that wants an immediate reduction.

Another benefit that is often overlooked is trace element addition. The anaerobic breakdown will slightly acidfy the bed and if you use an upper area of material that you would use in a calcium reactor you will get the slimmed down output that you would in a CaRx

One other important thing to note about these beds and more importantly anaerobic breakdown in general is the "black death". People will say that H2S (hydrogen sulfide) killed their fish. Having run a full on anaerobic digester with methane output and everything, I can say that this is not very likely. I think that actual mechanism for crashing the system in this way is this. Anaerobic breakdown is slow. Nutrients accumulate and there are a lot of them. If you release those nutrients into an oxygenated environment you are going to get an ammonia and nitrite spikes, in the face of rapid aerobic break down. For me this is what will kill the fish, because these spikes happen quickly. Most people don't think to test for this because they see the black area and smell the methane and assume that that is what caused it. Directly no, that didn't cause it, but indirectly yes.

Plenums and deep sand beds are great additions to salt water aquariums if implemented correctly and understood mechanically.

 

[ISpeakForTheSeas]

From everything I've read on the topic, it seems like the shift in popularity is the main reason. There are other options that works just as well for most people, but the DSB works fine. The risks associated with it seem largely to be second or third-hand anecdotes (hearsay) based on the slim chance of gases/nutrients getting trapped in the sand bed then released suddenly - I don't think I've ever seen someone actually claim with any evidence that this caused problems in their tank, but this is a widely claimed point against DSB's.

Honestly, most people seem to dislike DSB's because of the look and/or maintenance requirements (which, to my knowledge, really just involve getting sand sifting tank inhabitants and/or stirring the sand manually on occasion). This seems to be why remote DSB's are relatively popular, but bare bottom and 0-2 inch sand bed tanks are the popular display tank options at the moment.

 

[ReefGeezer]

I think that nitrate reduction is much better understood now and it isn't the boogieman it was at one time. Reefers now have trouble maintaining some level of inorganic nitrates. With that in mind, most would prefer to dedicate the 4-8" of space at the bottom of the tank to corals rather than sand. Think about it... a DSB in a 90 gallon tank occupies 15 to 30 gallons of space.

 

[Kitjo]

I have used plenums for 20 years.

They work, they are not risky, but they have caveats.

Implementation is everything.

Here is what I have learned about them.

Do NOT implement them in the main DT. The reason why is that the rock work that sits on top of them creates "shadows" this can impede proper movement through the bed. I have taken to implementing them in 6" PVC tubing. This helps with a couple of things. It ensures that the don't have things sitting on them. It gets them out of the DT, and finally it ensures their longevity. These things work best in the long term. There have been a bunch of scares about the plenums/deep sand bed re-leeching nitrates. This simply does not happen.

Many people want immediate reduction of nitrate. They will not do this. They take time to get going. There are implementation techniques that will make this process go faster but you are looking at at least 4 months to get one going. Also if more nitrate is being produced than they can consume then they won't reduce all of the nitrate. They have a capacity and that often gets lost on a lot of people. Since they are biological there is a ramp up and ramp down period. Meaning they slow the change of of nitrates. This is really helpful for someone trying to achieve balance, but totally frustrating for someone that wants an immediate reduction.

Another benefit that is often overlooked is trace element addition. The anaerobic breakdown will slightly acidfy the bed and if you use an upper area of material that you would use in a calcium reactor you will get the slimmed down output that you would in a CaRx

One other important thing to note about these beds and more importantly anaerobic breakdown in general is the "black death". People will say that H2S (hydrogen sulfide) killed their fish. Having run a full on anaerobic digester with methane output and everything, I can say that this is not very likely. I think that actual mechanism for crashing the system in this way is this. Anaerobic breakdown is slow. Nutrients accumulate and there are a lot of them. If you release those nutrients into an oxygenated environment you are going to get an ammonia and nitrite spikes, in the face of rapid aerobic break down. For me this is what will kill the fish, because these spikes happen quickly. Most people don't think to test for this because they see the black area and smell the methane and assume that that is what caused it. Directly no, that didn't cause it, but indirectly yes.

Plenums and deep sand beds are great additions to salt water aquariums if implemented correctly and understood mechanically.

I’d love to see a photo of the 6” PVC DSB if you have one.

 

[Cabinetman]

I think that nitrate reduction is much better understood now and it isn't the boogieman it was at one time. Reefers now have trouble maintaining some level of inorganic nitrates. With that in mind, most would prefer to dedicate the 4-8" of space at the bottom of the tank to corals rather than sand. Think about it... a DSB in a 90 gallon tank occupies 15 to 30 gallons of space.

I’d also like to see this pvc deep sand bed. Or have it explained a little more

 

[G Santana]

Many years ago when I started DSB were the rage, I had one in late 80s early 90s but I quickly transitioned to bare bottom as soon as I started to see positive results from local reefers.
When I started to remove my sand bed (slowly) I couldn't believe what was trapped in it.
Today I manage nitrates with Vodka and a BB tank.
I do miss the look of sand but not the mess.

 

[Sod Buster]

My old sump from years ago had a chamber dedicated to a DSB if you wanted to use it. The tube was so it didn't get stirred up from the overflow. 5"s of sand could be put in that chamber. I used it w/ rodi for ATO though.

 

[HuduVudu]

I’d love to see a photo of the 6” PVC DSB if you have one.

Ok these are some really terrible pictures but they are the best that I can do because I have to take the pictures from the top down through an Avast portal.

 

[Sod Buster]

Best I can do on my phone w/ a finger. Same as a piece of 6 inch by 6 inch pvc pipe stood on end on your sump. The sand is isolated from any disturbances. No powerheads or skimmer wash blasting the sand, just water going over it slowly. The sump pic has a empty tide pool tube to calm the overflow, sand all around the tube in red crayon, water blue. His is 6" pvc tube to protect from disturbances with the sand in the tube.

 

[ReefGuy1234]

Almost 20 years ago, when I was first going to start a reef tank, my plan was to do a deep sand bed. I loved the idea that deep sand beds (without sand sifting creatures) were an integrated part of the reef ecosystem. It appeared that there were a lot of people who had them for years and years.

It appears now that the hobby has moved away from this.

Is this because deep sand beds do not work?
Is this because deep sand beds are too risky?
Is this because deep sand beds have been replaced by something better?
Is this because deep sand beds have just shifted in popularity?

Is there anyone still starting new tanks with deep sand beds?

Thanks!

I'm not an expert at all but I have one and there's no problems other than it get very dirty. Also I don't think its very necessary unless you have fish that burrow.

 

[Borat]

I have used plenums for 20 years.

They work, they are not risky, but they have caveats.

Implementation is everything.

Here is what I have learned about them.

Do NOT implement them in the main DT. The reason why is that the rock work that sits on top of them creates "shadows" this can impede proper movement through the bed. I have taken to implementing them in 6" PVC tubing. This helps with a couple of things. It ensures that the don't have things sitting on them. It gets them out of the DT, and finally it ensures their longevity. These things work best in the long term. There have been a bunch of scares about the plenums/deep sand bed re-leeching nitrates. This simply does not happen.

Many people want immediate reduction of nitrate. They will not do this. They take time to get going. There are implementation techniques that will make this process go faster but you are looking at at least 4 months to get one going. Also if more nitrate is being produced than they can consume then they won't reduce all of the nitrate. They have a capacity and that often gets lost on a lot of people. Since they are biological there is a ramp up and ramp down period. Meaning they slow the change of of nitrates. This is really helpful for someone trying to achieve balance, but totally frustrating for someone that wants an immediate reduction.

Another benefit that is often overlooked is trace element addition. The anaerobic breakdown will slightly acidfy the bed and if you use an upper area of material that you would use in a calcium reactor you will get the slimmed down output that you would in a CaRx

One other important thing to note about these beds and more importantly anaerobic breakdown in general is the "black death". People will say that H2S (hydrogen sulfide) killed their fish. Having run a full on anaerobic digester with methane output and everything, I can say that this is not very likely. I think that actual mechanism for crashing the system in this way is this. Anaerobic breakdown is slow. Nutrients accumulate and there are a lot of them. If you release those nutrients into an oxygenated environment you are going to get an ammonia and nitrite spikes, in the face of rapid aerobic break down. For me this is what will kill the fish, because these spikes happen quickly. Most people don't think to test for this because they see the black area and smell the methane and assume that that is what caused it. Directly no, that didn't cause it, but indirectly yes.

Plenums and deep sand beds are great additions to salt water aquariums if implemented correctly and understood mechanically.

Pictures (of the tubing setup) would be most helpful!

Cheers...

 

[HuduVudu]

Pictures would be most helpful! Cheers...

I have posted pictures above.

 

[bruno3047]

DSB are used to maintain a denitrification process where the nitrate is converted back to nitrogen and oxygen (air). Unfortunately one of the byproducts of this process is hydrogen sulfide. That’s that rotten egg smell. This is poisonous to a reef tank if released in large quantities. If you’ve ever opened a canister filter after not opening it for a very long time or using it for a very long time and you get a rotten egg smell, that’s hydrogen sulfide a.k.a. sewer gas. I researched DSB’s when I first started with saltwater tanks. I didn’t think it was such a great idea but to each his/her own.

 

[HuduVudu]

This is poisonous to a reef tank if released in large quantities.

The devil is in the details.

How large of quantities are we talking about?

 

[vlangel]

Every tank I have ever had (except my seahorse tank) had/has a deep sanded. It's true that they should not be disturbed deep down where the sand is not aerated but none of my tanks ever turned toxic. When I took down an older tank, 10 years old or so the sand smelled just like fresh salt water and the bottom strata was a slightly different color where the anaerobic bacteria resided and did their magic. I also maintained tanks for a lfs in the early 2000s. That mom and pop store closed but some of the tanks that they set up are still going in their original set up. They absolutely work reducing nitrates plus they are very low maintenance if done correctly. I dance my fingers across the surface of my sandbed when I clean the glass once a week. That's all I do.

I have a tall tank so I welcome the DSB to take up some of the height. Here is a pic and although you cannot see it well, this is my tank with a tiered sand bed, some which is 7" deep.