Deep Sand Bed Questions

[phippsj]

OK, so I have been reading all over about DSB issues. I am finding a lot of conflicting information. I would prefer to use fine sand or extremely find sand (sugar grain). This is going for a 180G reef tank.

I have read in some places that you do not want the DSB any more than 3". Here on this forum I read that you want it either >1" or 4-6", and that anything in between is problematic.

My understanding is that the water flow should be restricted towards the bottom of the sand allowing the appropriate organisms to grow there. That being said, would the depth of the sand bed really depend on the size of sand being used to create the sand bed? Also, would the livestock going into the tank (engineer goby for example) have to be considered?

Can anyone point me to a reliable article on building and designing a DSB?
Thanks!
-jared

[JimD]

Theres gonna be a few opinions on this but in general....

Sugar grain or "oolitic" sand is prefered because of its added surface area.

One inch sand beds are refered to as "SSB" or shallow sand beds and have little buffering affect. 3"-6" is prefered and periodic replacement is very important.

Strong water flow is necessary in all areas in order to keep detritus suspended to reach the skimmer.

No, the size of the sand should not decide its depth.

Research in this area is very important, choose your sand critters carefully, I discourage the use of stars and any other animal that lives on the fauna thats in the sandbed... Snails, especially Nassarious and Fighting conches are preferred...

Hopefully, this will get on track, by the way, bare bottom tanks require completely different husbandry that you may be interested as well... Theres tons of info out there, just Google it... Good Luck!

[BIGBIRD123]

My older Brother just gave you some good advice...and Welcome to MAAST. Jared, also I would contact Ping ( His name is Peter) by PM here on MAAST because he knows and has a lot of information on DSB and Refugiums.

Steve

[phippsj]

Theres gonna be a few opinions on this but in general....

Sugar grain or "oolitic" sand is prefered because of its added surface area.

One inch sand beds are refered to as "SSB" or shallow sand beds and have little buffering affect. 3"-6" is prefered and periodic replacement is very important.

Strong water flow is necessary in all areas in order to keep detritus suspended to reach the skimmer.

No, the size of the sand should not decide its depth.

Research in this area is very important, choose your sand critters carefully, I discourage the use of stars and any other animal that lives on the fauna thats in the sandbed... Snails, especially Nassarious and Fighting conches are preferred...

Hopefully, this will get on track, by the way, bare bottom tanks require completely different husbandry that you may be interested as well... Theres tons of info out there, just Google it... Good Luck!

Thanks. I have googled this quite a bit, just kept getting different info from different sources. Perhaps I will leave the DSB to the refugium where it is easier to change.

[phippsj]

My older Brother just gave you some good advice...and Welcome to MAAST. Jared, also I would contact Ping ( His name is Peter) by PM here on MAAST because he knows and has a lot of information on DSB and Refugiums.

Steve

Thanks... been browsing without posting for a while now. Good info here!

[dmweise]

Replacing the sand bed sounds nasty. How often should it be done?

[JimD]

You dont have to replace the entire sandbed, I shouyld have made that clearer, sorry. Periodic partial removal and replacement is what is needed... The sandbed can only process so much nutrients then it begins to leach it back into the system. Most people will gently skim the upper layer of sand and replace it with new... This also helps with buffering...

[Ping]

http://www.maast.org/upload/March_Newletter_Premier.pdf

Sandbeds can be set up and maintained so as to never require the cleaning or removal of any sand. The safest way for a novice to start a sand bed; is to place about an inch of special grade argonite in the the display and have a four inch or greater depth Remote Deep Sand Bed. Some keys to keeping deep sand beds unclogged of detritus is current, a diverse amount of sand bed microscopic critters, and no animals that eat these micro critters.

Adding diversity comes from sand swaps, and the bi-annual addition of small pieces of freshly cured live rock.

Advection, the flows inside a sand bed, require moderate to high flow. This being said, the best flow over a deep sand bed is one where the energy is just below what allows the sand not to move.

[Ping]

Overfeeding the system or too high of a bio load negates some of this.

[phippsj]

http://www.maast.org/upload/March_Newletter_Premier.pdf

Sandbeds can be set up and maintained so as to never require the cleaning or removal of any sand. The safest way for a novice to start a sand bed; is to place about an inch of special grade argonite in the the display and have a four inch or greater depth Remote Deep Sand Bed. Some keys to keeping deep sand beds unclogged of detritus is current, a diverse amount of sand bed microscopic critters, and no animals that eat these micro critters.

Adding diversity comes from sand swaps, and the bi-annual addition of small pieces of freshly cured live rock.

Advection, the flows inside a sand bed, require moderate to high flow. This being said, the best flow over a deep sand bed is one where the energy is just below what allows the sand not to move.

Thanks for the link to the article. The sand I was looking at is a sugar grain argonite. Initially I was hoping to do a 3" bed. I really don't have a problem going with a 4" bed (or greater if that is better). The tank is a 180 gallon, and I am currently working on the rock wall build (like Tigsy and others on ReefCentral have done). Right now I have all my Marco rock being built witha 3" ledge from the bottom of the tank to the start of the wall... so I could do the other two panels with a 4".

So, if I went ahead with a 4" and put in a fighting conch, would you say I am heading the right direction or am I going for a nose dive? In terms of flow, I was planning 7200 gph (of which 1200 gph go through the sump).

[Ping]

Sugar fine sand is purported to be the best sized grain for a DSB and is what I use for DSB’s. A depth greater than 4 inches would be better as the idea is to have a completely anaerobic layer at the bottom of the sand bed. Along with denitrification, the sand will very slowly dissolve under these anaerobic conditions and get shallower with time, providing very minor supplementation of beneficial elements. Therefore, the deeper the bed is when initially setting up a DSB, the better.

Some potential problems with a DSB in the display: The rock work may become unstable over time because of the dissolution of the aragonite. Detritus may build up in areas not receiving enough current. Aquarists have a tendency to put critters in the tank that are detrimental to the DSB as they consume the beneficial sand bed life forms that are slowly stirring the sand bed and turning detritus into inorganic insoluble elements. As well as the inclusion of critters that rapidly disturb the layers of the sand bed, eliminating some of the sand beds denitrification benefits. All of these potential pitfalls can be overcome if the Marine Aquarium System is properly planned and these factors are adjusted for.

Each aquarist setting up a DSB must consider the expectations of the DSB. I believe the only reason a DSB should be placed in the display tank is to support animals that require a well established DSB in order to thrive, such as sand sifting gobies and cucumbers. Most systems with live rock, strong current, and a protein skimmer do not require a DSB for denitrification unless the closed aquarium system has too high of a bio-load e.g. too many fish.

[Troutmasters02]

Thanks for the info Peter. I have a DSB in my refug and I am wondering if there is an ideal range of flow over the sandbed? Is there such a thing as too much flow over a deep sand bed which would prevent the anaerobic layer from doing its job?

[JimD]

Enough flow is when the detritus is suspended, too much flow is when the sand is suspended...

[Ping]

Here is where a DSB gets convoluted, if the DSB is located in a refugium, much gentler water flow will preserve their productivity (Sprung 2005) and personal experience. One reason why this works is there is nothing to interfere with the current causing dead zones and the large pieces of waste have been broken up by the time it gets into the refugium. I use a MJ 1200 in a 55g DSB refugium. No rocks and only a few Caulerpa Prolifera.

Reef Crest currents are aimed at preventing dead zones, keeping the pores of the rock open, and removing the wastes from coral. Attempting to mimic the tremendous energy of the ocean.

[NeptunesGhost]

Enough flow is when the detritus is suspended, too much flow is when the sand is suspended...

:rofl: Well said

[Troutmasters02]

Here is where a DSB gets convoluted, if the DSB is located in a refugium, much gentler water flow will preserve their productivity (Sprung 2005) and personal experience. One reason why this works is there is nothing to interfere with the current causing dead zones and the large pieces of waste have been broken up by the time it gets into the refugium. I use a MJ 1200 in a 55g DSB refugium. No rocks and only a few Caulerpa Prolifera.

Reef Crest currents are aimed at preventing dead zones, keeping the pores of the rock open, and removing the waists from coral. Attempting to mimic the tremendous energy of the ocean.


Makes sense, thanks for that.

[gjuarez]

This has been very well explained by Ping. Anaerobic bacteria grows where there is very little oxygen, the anoxic zone. That is why a DSB is required to be deep. Earlier it was mentioned that the size of the grain doesnt matter, in my opinion it does. That is why sugar fine sand is recomended, because the grains are so small and tighly pressed together that they do a better job at blocking oxygen into the dsb. Normally a deeper sand bed when grains are larger.

DSB work, they are great in my opinion. Just like Ping mentions, I also only recomended only if it is required for some critters. In the earlier days, the days before skimmers, you couldnt go without one as it was the main source of nutrient export. Thanks to skimmers, more often than not we can afford to go without one. Increase the flow, eliminate dead zones, and turn up the skimmer is the most popular way these days.

BTW, live rock is also great for establishing anaerobic bacteria. It grows very deep inside the rock. The great thing is that it also has alot of surface area where aerobic bacteria grows.