Are the risks of having a deep sandbed exaggerated?

[vlangel]

I have always been a fan of DSBs. They can be very effective in helping reduce nitrates in a tank with a heavy bioload. Those of us that love fish and like to feed them well appreciate this benefit. Other than having some nassarius snails and an Atlantic cucumber, a DSB requires no maintenance at all. There is no vacuuming necessary.
However, I know that not everyone agrees that these benefits are worth the risks. I am curious about your thoughts and if it's based on your own personal experiences or hearsay from other reef keepers.

I will start. I have had 4 tanks with DSBs and all 4 flourished. The longest one was in a 90g tank from 2001 until 2012 and when I downsized that tank the sand smelled like the ocean and not sulfurous at all. The tank I have now is coming on its 8th year with a DSB. DSBs were common when folks were setting their reefs up according to the Berlin method. With a DSB it is important to leave the sandbed undisturbed except the top 1" to encourage anaerobic bacteria to colonize the deeper, low or no oxygen areas of the sandbed. Secondly, one does not want to release hydrogen sulfide gases into the tank in significant amounts as this can be deadly. However, I do feel the actual incidents of that occurring are much lower than folks think. I worked at a lfs for 12 years where my boss set up many of the store's client's tanks with DSBs. I maintained those tanks for years and years and never experienced even 1 crash due to gas poisoning. One of those tanks, ( belonging to a close friend of mine) had a very heavy bioload and a sandbed that was over 23 years old before a different accident crashed it. I would be curious to hear firsthand accounts of folks whose tank crashed from DSB poisoning and what brought on the incident. I would also like to hear from folks like myself who have had DSBs and never experienced a hydrogen sulfide poisoning event so the reef community as a whole can more accurately assess the risk of employing a DSB.

 

[revhtree]

This should be a great topic! Following!

 

[brclark82]

How deep would a deep sand bed be considered to be?

 

[vlangel]

How deep would a deep sand bed be considered to be?

Generally to be considered a deep sandbed it needs to be minimally 4". Mine is 4" at the most shallow part but is 7" in the deepest area.
One can kind of gauge if it is working by looking for worms or worm tracks in top layers of the sandbed.

 

[PPBlimpy]

Back in 2002, my previous journey into saltwater aquaria I had a 180G that ran a DSB. 4-5" over a 96x24 foot print. That tank Had way to many fish and never had nitrate problem. Tank was taken down in 2005 and I left the hobby.

Fast forward to this past year I got back into reef keeping and realized no one sems to keep a DSB anymore. Lots of things actually changed. Current tank is a 125G with approx 1" of sand bed. I can not keep nitrates down for the life of me. I had previously came to realize how much the DSB was helping.

Next week I am jumping back to a 300g and I plan to run a 4"+ DSB but only in my 125g sump.
main tank will have 1-2" hopefully

I have a refugium chamber and a Frag chamber both are 20"x9" foot print an both will have 4" DSB. so approx 1440 sq inch of deep sand bed. I am hoping this helps with my nitrate problems as it did in my old tank.

I figure running it in my sump, and in 2 different chambers may be a safer way to keep it. If i need to disturb it and clean it out after a number of years I can shut off flow, scoop sand out and not grenade the tank. all while still having a second established DSB still thriving.

We will see how it goes.

 

[World Citizen]

I dropped my modern Refugium and went back to a large sump with live rock and soft corals.

I am considering reintroducing true oldschool DSB. Like @PPBlimpy is talking about.

I had such great results with this combination and i feel it is far more stable then any refugium.

Thats just an opinion.

Back to large sump and DSB!

 

[ieatbugman]

I have a 5 gallon planted pico tank with a yellow headed jaw fish and a little clown in it. The sand bed is about 4" and everything is doing great.

 

[56longroof]

The horror stories are always passed on information. To date I have never heard any first hand accounts of a DSB crashing a tank. There are always underlying causes that usually are due to neglected tanks. The benefits of a DSB are incredible in that it is very effective at nutrient reduction and it simplifies tank maintenance. No high tech gadgets to maintain or monitor. I had one back in the 90's and it made me a believer. My current set up has a 5-6" DSB and my nitrates struggle to reach 10 ppm with alot of fish and feeding heavy 3 or 4 times a day.

 

[PPBlimpy]

Now if we can find another way to remove phosphates like a DSB removes nitrates we would be golden.

I know macro algae helps and a small percentage of phosphates is processed thru DSB but i am tired of relying on GFO. I prefer to not ad stuff if i can find a more natural way. Starting to look into an algea scrubber as I think that is my best bet

 

[Science/G]

Old Tank Syndrome? Does the sand bed become so over-saturated with waste that there is an eventual catastrophic release of Hydrogen Sulfide? I am a bare-bottom reefer. I am more comfortable with other nutrient export methods.

 

[56longroof]

Old Tank Syndrome? Does the sand bed become so over-saturated with waste that there is an eventual catastrophic release of Hydrogen Sulfide? I am a bare-bottom reefer. I am more comfortable with other nutrient export methods.

That falls into lack of maintenance.

 

[Randy Holmes-Farley]

I'm not really concerned about any "risk" from them, but I'm also skeptical that they provide much benefit unless water is somehow encouraged to flow through them (plenum, reverse flow etc.).

I had one for a while. I didn't think it did much good or bad, and removed it. :)

 

[Science/G]

That falls into lack of maintenance.

How?

 

[56longroof]

How?

A sandbed becoming clogged up with detritus is lack of maintenance or proper clean up crew. A DSB is not a set it and forget it method. There are some required tasks. Not much or very often but still required. Old tank syndrome is caused primarily by lack of tank husbandry so even a bare bottom tank can be a victim of it.

 

[brclark82]

Not to derail but how does a DSB help with nutrient reduction if it has to be left undisturbed for anaerobic bacteria to colonize. How do those bacteria interact with the water in the tank if they are 4 inches below the sand bed with no water exchange etc?

 

[56longroof]

Not to derail but how does a DSB help with nutrient reduction if it has to be left undisturbed for anaerobic bacteria to colonize. How do those bacteria interact with the water in the tank if they are 4 inches below the sand bed with no water exchange etc?

There is water exchange. It's just done slowly.

 

[CoastalTownLayabout]

I think the important thing to remember with DSB tanks from the late 90”s - 2000’s was that they were almost always established with proper live rock.

They were definitely easy to get going but had some drawbacks. Getting strong flow for acros was tricky with the fine sand.

Otherwise I had a lot of success with them and also Jaubert set ups.

There was a thread on RC back in the day by a guy called Bomber that scared a lot of people off them.

 

[vlangel]

I think the important thing to remember with DSB tanks from the late 90”s - 2000’s was that they were almost always established with proper live rock.

They were definitely easy to get going but had some drawbacks. Getting strong flow for acros was tricky with the fine sand.

Otherwise I had a lot of success with them and also Jaubert set ups.

There was a thread on RC back in the day by a guy called Bomber that scared a lot of people off them.

That is true about using live rock. All 4 of my tanks were set up using live rock. And you make a good point about very fine sand and high flow loving acros. My tank has pretty high flow now but it's also a tall tank so not super brisk at the sandbed level. I don't keep acros as my tank is an LPS/softie/macro display.

 

[mook1178]

Not to derail but how does a DSB help with nutrient reduction if it has to be left undisturbed for anaerobic bacteria to colonize. How do those bacteria interact with the water in the tank if they are 4 inches below the sand bed with no water exchange etc?

It is not so much water moving through the sand but more the nitrates moving into the sand by concentration diffusion.

 

[mook1178]

I think the important thing to remember with DSB tanks from the late 90”s - 2000’s was that they were almost always established with proper live rock.

They were definitely easy to get going but had some drawbacks. Getting strong flow for acros was tricky with the fine sand.

Otherwise I had a lot of success with them and also Jaubert set ups.

There was a thread on RC back in the day by a guy called Bomber that scared a lot of people off them.

I set mine up with sand from the beach and dry rock. Granted it was wet sand so had the bacteria, but it was in the tidal zone with lots of wave action, so not much in terms of worms and such.