The everlasting debate on deepsand beds.

[sawyerc]

I'm setting up my new 55 gallon soft coral tank with a basement sump system - a 30 gallon refugium and a 30 gallon dark deep sand bed. I've always just used 3 inch sand beds in the tank so I don't have any experience with DSBs. I've read thread after thread and countless websites disussing their merits and downfalls but I thought I would open up the discussion again. The sandbed will be SEPARATE from the main tank, the flow to the sandbed will be controllable from 400GPH to 0GPH, and there will be nothing directly on top of the sandbed. I'm using Southdown sand, probably about 8inches deep and seeding with garf grunge. I don't intend to ever touch the sand bed once I've set it up. I'll also try to grow some sponges in the dark area of the tank. I'm expecting the sandbed to help reduce nitrates and phosphates without producing any other long term problems or benefits. Opinions....?

 

[Anonymous]

I had a basement sump with a DSB in it, about 8 inches as you are doing, in a 100 gal tub.. There was no rock or anything on the bed. I had seeded it with live sand from other people's tanks, as well as several different critters from IPSF.

My sand bed eventually failed after several years. It was full of thick layers of detritus when I pulled it out. I have thought that having the tub that held the bed on the floor of the basement may have led to the death of sandbed critters, if it got too cold, but I don't know.

Anyway, whether is was user error or not, I don't use DSB anymore (well, I have one in a tiny tank on my system that I have yet to remove) because I always had zero nitrates before installing the bed, so I didn't see any reason to try and continue to use one.

 

[Anonymous]

You might consider "crude" from Premium Aquatics as an alternative to grunge. I have no idea what GARF charges, but crude is only $1.49 per pound. Its mud and rubble from the bottom of their live rock curing tanks. I got a lb once, it was full of mini brittle stars, shells, pods, all kind of stuff. I doubt you would need more than a pound.

 

[Anonymous]

You might consider "crude" from Premium Aquatics as an alternative to grunge. I have no idea what GARF charges, but crude is only $1.49 per pound. Its mud and rubble from the bottom of their live rock curing tanks. I got a lb once, it was full of mini brittle stars, shells, pods, all kind of stuff. I doubt you would need more than a pound.

Many LFS will give you the small rubble and mud from their curing tanks as they just toss it, all ya gotta do is ask.

Regards,
David Mohr

 

[DonJasper]

sawyerc":z5vahtcd" data-source="" class="bbCodeBlock bbCodeBlock--expandable bbCodeBlock--quote js-expandWatch">

I'm expecting the sandbed to help reduce nitrates.

Yes.

and phosphates

No.

This is what I would do:

4" or so is all you need to create an 'oxygen free zone' at the bottom. The nitrate eaters live there, and they crap nitrogen gas. Stagnant sand = trouble. So add plenty of little things that move the sand around in tiny bits. If you stir the sand - the layers of communities that develop inside the DSB die, and bad things happen. Besides that's what worms and the other weird sand creatures do best. Larger creatures sold as 'sand sifters' (stars, gobies etc) eat their way through the top sand layer creatures. With them gone - the lower layer creatures don't have anything to do - and they leave.

I wouldn't want the extra 3" sitting around. The best that could happen is that whatever starts living there doesn't hurt anything, and is merely useless.

I’ve never heard anything the process phosphates into something else (like nitrates eventually being processed in N2 gas). So that’ll have to be exported, I believe. I'd use plenty of macro and occasionally remove it and discard it and the phosphates contained inside. While doing that I’d check to make sure there’s (still) got lots of squirmy things in the sand bed. Over the years - some species of the squirmy things might go extinct on you - so you may have to re-introduce the critter kits. Sorry I don't think that there's anything that’s "no” maintenance " only "low maintenance".

That’s my opinion.

 

[Anonymous]

I had a basement sump with a DSB in it, about 8 inches as you are doing, in a 100 gal tub.. There was no rock or anything on the bed. I had seeded it with live sand from other people's tanks, as well as several different critters from IPSF.

My sand bed eventually failed after several years. It was full of thick layers of detritus when I pulled it out. I have thought that having the tub that held the bed on the floor of the basement may have led to the death of sandbed critters, if it got too cold, but I don't know.

Anyway, whether is was user error or not, I don't use DSB anymore (well, I have one in a tiny tank on my system that I have yet to remove) because I always had zero nitrates before installing the bed, so I didn't see any reason to try and continue to use one.

In all likeyhood it failed due to lack of food. Sandbeds must also be periodically infused with more critters.

Jim

 

[Anonymous]

My sand bed eventually failed after several years. It was full of thick layers of detritus when I pulled it out.

In all likeyhood it failed due to lack of food. Sandbeds must also be periodically infused with more critters.

Jim

Sounds like it had plenty of food ( detritus ) I'd say most likely a lack of critters.
Yup people forget that they need to replenish their sandbed critter base.

Regards,
David Mohr

 

[Mouse]

IPSF Rocks, go check em out

 

[Anonymous]

My sand bed eventually failed after several years. It was full of thick layers of detritus when I pulled it out.

In all likeyhood it failed due to lack of food. Sandbeds must also be periodically infused with more critters.

Jim

Sounds like it had plenty of food ( detritus ) I'd say most likely a lack of critters.
Yup people forget that they need to replenish their sandbed critter base.

Regards,
David Mohr

Trouble is there's not much written about that, so it's easy for people to be ignorant of that information. Timespan too is fuzzy. Every 2 years might be a good ball park time frame.
Len has had his runnig for forever and a day, so I know they can work for longer than the naysayers think.

Jim

 

[sawyerc]

Thanks, guys. I'll probably go ahead and install it. I can always disconnect it with a simple valve turn. I sounds like I should be okay as long as I put new critters in every year or two.

 

[Anonymous]

Morning!

IIRC, Len also never recharges his sand critters, only runs three inches, and skims like a mofo.

There seems to be little science to support the idea of DSB in the Dr Ron sense - never touch it and keep adding critters to it.
Sand does a great job of denitrifying until the sand gets filled up with detritus. Contrary to the Dr Ron school, it appears that a sand bed and fauna simply cannot break everything down forever. Once the bed 'fills', just like any other clogged filter it starts releasing stuff back into the water - mostly phosphate. You can extend the 'life' of a sand bed by not letting fill up (BTW, this 'filling' time is different in different tanks and it may simply be that Lens hasn't 'filled' yet).
In a remote sand bed one way to do this is to run the water entering the sand bed sump through a filter sock to catch any detritus before it hits the sand. However, Dr Ron says that a remote sand bed in ineffective and shouldn't be used.
The evidence that mixing the layers of a sand bed is disastrous seems also to be not supported, as does the whole idea of defined layers in the sand. It seems that sand beds are always in a state of flux, and instead of layers, there are zones of different aerobic/anaerobic levels that tend to move around at different depths. Personally, it seems to me that the idea that stirring the sand bed is bad comes from stirring sand beds that are 'full'. When that happens, whatever the sand bed was 'full' of goes out of the sand and into the tank with unpleasant effects.
I stir my sand bed regularly with a power head while running a filter sock on the overflows, crank up the skimmer and a canister filter with a micron cartridge on the tank to collect the gunk. My goal is to export the detritus and phosphates before the bed 'fills'.

 

[Unarce]

This one needs my DSB template:

If you were to set up a reef tank with high current, than there would be a lot of bare areas if you had a SB less than an inch high. 2-3 inches is the absolute best way to go. It would be incorrect to claim that a sand bed provides 'more capacity to nitrify and denitrify' simply because it's deeper.

"As much as 70 to 90 percent of the overall denitrification was located in the uppermost centimeter. The remainder was found at 1-3 cm depth"

-T.K. Anderson 1984 "Diurnal Variations of Nitrogen Cycling in Coastal, Marine Sediments."

"anaerobic habitat can be as small as 1mm, that aerobic and anaerobic bacteria essentially coexist, and that as little as 0.08mm distance is sufficient for nitrification and denitrification to take place simultaneously."

-Ecology and Evolution in Anoxic Worlds. Oxford University Press, Fenchel, T. and B.J. Finlay. 1995.

The misunderstanding is that areas with low levels of oxygen are a must for denitrification. Since we now know that aerobic and anaerobic bacteria exist together in the upper portion of the SB, than the heavy oxygen levels of our tanks would not be a factor. It's unlikely that denitrification will occur in the deep areas of a DSB, especially if nitrates never reach it in the first place.

I'd also like to point out that a deeper sand bed doesn't necesarily equate to more biodiversity of life. A shallow sand bed of numerous grain-size will create a number of different environments housing more life than a DSB.

 

[Anonymous]

Morning!

IIRC, Len also never recharges his sand critters, only runs three inches, and skims like a mofo.

There seems to be little science to support the idea of DSB in the Dr Ron sense - never touch it and keep adding critters to it.
Sand does a great job of denitrifying until the sand gets filled up with detritus. Contrary to the Dr Ron school, it appears that a sand bed and fauna simply cannot break everything down forever

I've never had to either and mostly with only 2 1/2" deep beds but it seems that in the past couple of years I was away from reef keeping people have swung the other way and are now severely underfeeding their tanks. I make sure there's plenty of food for the copepods, isopods, amphipods, worms, etc. by not just feeding the fish but sand bed critters also. If you're underfeeding, the sand bed critters will starve and die therefore these people will have to recharge their sand beds with new critters.
btw the pods and the worms will stir up your sandbed just like your powerhead though it's just not as noticable.

Regards,
David Mohr

 

[Unarce]

are now severely underfeeding their tanks.

I've kind of been puzzled by that trend, too. On top of fish feeding and phytoplankton, I even throw a few pellets into the sump.

 

[Anonymous]

hese people will have to recharge their sand beds with new critters.
btw the pods and the worms will stir up your sandbed just like your powerhead though it's just not as noticable.

Don't know if I can agree with that .
When I 'stir' with a power head lots of detritus goes into the WC and I export it. I don't see how sand bed fauna could get detritus out of the sand so it could be exported. Sure they may move it around, but it still stays in the bed doesn't it?

:mrgreen:

 

[Anonymous]

hese people will have to recharge their sand beds with new critters.
btw the pods and the worms will stir up your sandbed just like your powerhead though it's just not as noticable.

Don't know if I can agree with that .
When I 'stir' with a power head lots of detritus goes into the WC and I export it. I don't see how sand bed fauna could get detritus out of the sand so it could be exported. Sure they may move it around, but it still stays in the bed doesn't it?

As stated above it's just not as noticable. You storm your bed with a powerhead and the tank gets cloudy for a while while your skimmer removes the crud. The sand bed critters gently stir it up, it will be picked up by circulation and will be suspended in the water column and the skimmer will remove it or filter feeders will consume it. You should see the amphipods stir up my sand bed, it's like watching an ant farm. The Bristle Worms tool around the live rock stirring the detritus. While my tank water may look clear I can assure you that it is filled with microscopic detritus. Why does your skimmer remove crud when you don't storm the tank ? It's more than just circulation and fish. At the moment there are no fish in my tank.

Regards,
David Mohr

 

[Anonymous]

Gotcha. Its not that I don't think the critters stir it at all, its just the amount kicked up by the critters is not enough to deal with the 'filling' up process..

I have an active sand bed with tons o critters. When I 'stir' with a power head I do it over several days, and by the end, there is far less goo to get into suspension. 4 months later the sand has lots of goo in it again. So it seems that they are unable to keep up with detritus production.

 

[Anonymous]

I have an active sand bed with tons o critters. When I 'stir' with a power head I do it over several days, and by the end, there is far less goo to get into suspension. 4 months later the sand has lots of goo in it again. So it seems that they are unable to keep up with detritus production.

Is it possible that your tank would be considered overstocked ? I'm not talking fish-wise. Well Maybe. Our tanks of course are nowhere like the real reefs so maybe we're cramming too many corals and fish, etc. in our smallish by comparison tanks. Corals produce waste and I see pics all the time of tanks just crammed with corals. Just a thought I'll throw out for discussion.

Regards,
David Mohr

 

[Anonymous]

You betcha about the overstocking, but pretty much an glass box is overstocked!

Here is another one to throw into the mix.
Dr Ron style DSB's are lagoon-al and not often found around reefs.

This is fun

 

[Anonymous]

You betcha about the overstocking, but pretty much an glass box is overstocked!

Yup but I've seen pics with corals so crammed in, they don't even have room to expand.

Here is another one to throw into the mix.
Dr Ron style DSB's are lagoon-al and not often found around reefs.

This is fun

I'll have to go back over Shimek's and Toonen's articles as it's been years since I've read any of them over even corresponded with the two of them.
Well yeah it's supposed to be fun and also interesting. After all that is what it's all about.

Regards,
David Mohr