Quote: Originally posted by rfoote on 12 March 2003

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Been thinking about it and I'm thinking my best option is probably to throw on a refugium with a real dsb in it.  Only problem is it would have to go in the basement.  I'll have to figure out a way to get the water back up and into the tank.

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Hijacked this post from the high nitrates thread...it was getting long and this is bit of a tangent.

I've got a question for the DSB crowd (I may be showing my great ingnorance here as I've had no experience and read little in this area).

Isn't one of the selling points of using a DSB over a plenum the fact that excess detrius, uneaten food, and other organic matter that normally falls to the bottom of the aquarium and "rots" (to ultimately nitrate), is eaten by small critters (detrivores) living  in the sand?  Therefore you don't "sift" the sand (either by hand or by gobies, sandstars, ect).  You rely on the small detrivours to do the sifting for you.  You don't stick a Python tube down into your DSB.  You also have the nitrogen cycle working for you converting nitrate to gaseous nitrogen deep in the bed (anaerobic) for export back to the atmosphere.

On the other hand,  a plenum system doesn't have (as many) detrivours doing their thing, therefore the excess detrius should be sucked up from the substrate (upper inch or so) when doing water changes.  You still have the nitrogen cycle doing it's thing as in a DSB.

If the detrivours in a DSB are to be utilized (i.e. fed), shouldn't the sand bed be in the aquarium and not in the sump or refugium?  I'm not saying that a DSB in a refugium is a bad thing, I'm just wondering if the full benefits of using a DSB would be obtained if the bed were outside the aquarium.  I really doubt you could have enough water movement to keep the detrius suspended in the water column long enough for all of it make it's way to the refugium.

Quote: Originally posted by rfoote on 13 March 2003

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I think the idea is in most refugiums is you have a dsb, as well as some live rock, macro algae and so on - creating in essence a miniature reef in the refugium for the nitrogen cycle to take place there as well.  Check out this link  http://www.rshimek.com/reef/sediment.htm">http://www.rshimek.com/reef/sediment.htm  From everything I've read this guy knows what he's talking about.  Some uproar on an article he wrote about IO Salt though apparently?  Let me know what you think!

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Yes it appears that a DSB in a refugium is commonplace, with some denitrification taking place in the sandbed.   I'm just questioning/wondering/don't really know if it's better to have the sand in the aquarium or refugium.  Seems to me if you want the detrivores to consume the detrius the sand should be in the main tank where the detrius is.

Yup, what little I do know (or think I know) about DSB is from reading Shimek.  I wouldn't mind trying one of the salts that did well in his test too, but I don't think anybody carries it locally.

Although there are organisms that eat the detritus in the main tank this is usually not the reason people have deep sand beds.  Most deep sand beds are used to remove nitrates.  This process can happen in the tank or in the sump.  The small organism are not responsible for the removal of nitrates, bacteria is responsible.

Quote: Originally posted by Jake Pehrson on 13 March 2003

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Although there are organisms that eat the detritus in the main tank this is usually not the reason people have deep sand beds.  Most deep sand beds are used to remove nitrates.  This process can happen in the tank or in the sump.  The small organism are not responsible for the removal of nitrates, bacteria is responsible.

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Isn't the fact that the detrivores keep the bed stirred and keep the volume of detritus down (thereby keeping the nutrient "storage" to minimum) the reason Shimek advocates DSBs?  Otherwise why not just do a plenum?

...learning something new every time I log on :) 

Quote: Originally posted by GonZo on 13 March 2003

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Part of the reason I have a refugium with a DSB is to provide a safe haven for the mentioned "small critters". They multiply and get sucked into the main tank, there to multiply again. But as the main tank is much larger, and there are larger critters (crabs, gobbies, ect.) that eat them they will multiply and fill the space on a much slower scale. Without this space they can call their own it would take quite some time to get a continuing population of small critters in the main tank. The DSB is their home and provides a place for the bacteria.

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Gonzo, this is exactly the main reason I would put a refugium/DSB in my system. 

Refugium are the best idea to come into reefing (imo) in the last 5 yrs.

I agree with Shimek that having organisms in your DSB will help reduce the nutrient "storage".  I highly recommend having a DSB in your main tank.

The fact remain that having the DSB in your main tank or in the refugium accomplishes almost the same thing with the exception of the main tank DSB having an increased capacity in removing detritus in the main tank, but on the other hand a refugium DSB will harbor more �small organism� than in the main tank because of the lack of predators, creating not only food for your main tank but still acting as a nitrate reducing area (sorry for the run on sentence).

As for the plenum argument.  I don�t use them myself.

The question is what does a plenum add that a DSB doesn�t have?  In my opinion nothing (but I have changed my mind in the past).

Hey jake,  are you going to talk about this sort of thing in the next meeting (or will you be talking more about mechanical and chemical filtration)?  I've always been more intrigued by the biological aspects of filtration.  How 'bout a discussion of "Making the nitrogen cycle work for you!".

I'd be inclined to agree, from a diffusion standpoint, that there's really no need for a plenum.