# RDSB questions



## ReefABCs (Nov 10, 2012)

I'm thinking of setting one up to help control nitrates long term. 
I plan on building a cabinet beside the display to house all the wires, controllers and light ballasts etc.. and was thinking to leave room for a RDSB at the bottom. (I might even make it so I can have a small refuge at the top of the stand for copepods or maybe a sea horse as well)

The size I would have room for is approx., 24Lx12 wide and maybe 12 high. Ideally I would want one built out off acrylic so I could split the sand in 3 sections with acrylic dividers if I need to change out some of the sand in the future. 

What size sand and type? Live sand or just reg? 
Will 7 inch of sand depth be ok?
How much flow over the sand and how much water depth over the sand?
This size would provide 288sq in of surface area is that enough to make a diff worth the effort on a reef system with about 180 total gal of water? 

Anything else I am missing? Thoughts on this? 

thx


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## J_T (Mar 25, 2011)

In my opinion; 

you won't have enough surface area to fully benifit from the DSB. I think you would do much better making it a live rock tank, and cheato. This will let it add pods to the system, and remove nutrients. 

You will get more bio diversity from the rock, and cheato as a refugium, than you will from the sand.


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## ReefABCs (Nov 10, 2012)

JT thanks for the reply.

I did a bunch of surfing on RC and I think my plan should work well with my system size.

Guys are using 5 gallon buckets to support up to 120 gal systems. Anthony Calfo ran a 55gal aquarium to support a 2000gal Fish only system.
It depends on your bio load of course.


some other answers to my own questions 
-smaller sand grain is better 1mm, aragonite is good as well as it helps to buffer the system.
- good flow as not to allow detritus to accumulate, diffuse the flow so it does not cause the sand to blow aro. 250gph over a 5 gal bucket is lots for eg.
Water flow should be about 2in above sand.
Depth should be about 5+ inch I did not find yet if say 12 in is a waist so my idea of 7inch seams about right. 
A std 12in salt bucket is only 113 sq in so my idea of approx 12x24 and 288sq inch should be good for my system size, I also read somewhere rule of thumb 25% of DT surface area.

It will be a month at least before I will get started on this as I need to build the stand to house it but I will let you know how its working. The thing is right now because my tank is so new and lots of rock and sand in the DT I don't have any Nitates to show improvement against, not a bad thing at all as that is the goal behind this to keep it that way long term.


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## ReefABCs (Nov 10, 2012)

oh yeah re the cheto idea,
I have some in my sump already but also questioned maybe more of this would be better but then read this question and response from Anthony Calfo.

Question is, is this method of nitrate reduction more efficient than macro algae growth? Would I gain addition benefit from also growing and pruning macro in addition to this method? 

Anthony reply -macroalgae in the sump cannot even begin to compare in potential (its inferior) in this application if typical sump.``


Note: the RDSB is to reduce Nitrates only.


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## J_T (Mar 25, 2011)

ReefABCs said:


> oh yeah re the cheto idea,
> I have some in my sump already but also questioned maybe more of this would be better but then read this question and response from Anthony Calfo.
> 
> Question is, is this method of nitrate reduction more efficient than macro algae growth? Would I gain addition benefit from also growing and pruning macro in addition to this method?
> ...


okay... if we are going to open this can of worms, lets just rip the lid off!

DSB, will handle nitrates, true. But, they require maintance. That bucket that people use, is just that, a bucket. When the DSB is working, its like there is a hole in the bottom. When you fill it with nitrates, it drains out (gets processed). If that hole plugs up, the pail fills. This is where DSB's were dubbed "time bombs" they will keep on filling.

So, if you have a pail sitting somewhere, are you going to be always checking that the snails, and other micro critters are still alive, and thriving! Not likely. So, the usefullness of the DSB becomes less, and less, and eventually becomes harmfull.

On the flip side. The refugium will process larger particles from the pods, and bio diversity of bacteria. This processes the waste right through, thus not causing a nitrate problem. It also has other benifits. The fish get a constant food source. The filtering ability will grow, and reduce based on your tanks needs. If left unattended, it just over grows!

So, I guess it depends on how you want to look at things. I still believe the refugium would be of more benifit on the whole! Nitrates shouldn't be a problem in our tanks if we are doing our jobs properly, and setting the tank up right from the start!

I would like to add that I have had DSB's in my tanks for over 10 years now. So, I am not trying to argue that they don't work. Instead, I think that a refugium would be better.

If you filled the bottom of the remote sump tank with live rock, and the top half with cheato, you would have a pretty solid tank.


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## ReefABCs (Nov 10, 2012)

Good discussion 

I was not planning on adding any snails or critters at all. Apparently not needed in a RDSB. I get the idea that once its `full`of nitrates it stops working but what is the concern I just replace the sand and will Know if Nitrates start to rise.

Good point on if the return gets plugged so I plan on a larger hose for the exit, not sure yet what exactly maybe 2 for insurance. 

PS I have a small fuge type area in the sump approx. 5 in of fine live sand and cheato in a 16x12 area with a small pwr head for some extra flow.


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## J_T (Mar 25, 2011)

ReefABCs said:


> Good discussion
> 
> I was not planning on adding any snails or critters at all. Apparently not needed in a RDSB. I get the idea that once its `full`of nitrates it stops working but what is the concern I just replace the sand and will Know if Nitrates start to rise.
> 
> ...


without critters, its just not doing much. It needs the top layers to be stirred regularly in order to keep the crud moving, and exposing the lower sand to the water.

If you are going to add the bucket/tank, and I realize that this is under $50 investment, you may as well do it right! Stick some nassarius in there, and a couple ceriths. If you can find some bristle worms, I would drop them in there too.

You need to have something to eat the larger particles. The sandbed can't do anything with a full pellet, but once 5 snails eat it, and poop it out, then it can work with that!


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## wildexpressions (May 3, 2010)

for the purpose of convo you need to define whether you are building DSB, a RSDB or a bucket DSB. They are all different and none of them really work well unless you follow pretty specific design/setup.

The bucket DSB ( I know peeps call it a RSDB but it makes it confusing as there are several types of RSDB's) Anthony's system is very specific and it requires no maintenance and he has had them running as long ass 10 years apparently.

He uses a bucket and he is very specific about the setup and makes a point of stating it will not likely work if you deviate much. Sand particle size, I think 1mm is the top end for a bucket DSB but i believe grain shape has a greater effect. oolitic sand is likely a good choice but I'd confirm that before acting on it

Anthony's bucket RSB's are built as as follows ( please correct me if I'm wrong as I no longer have the article at hand)


Uses old salt bucket
fills with oolitic sand of approx .05mm to within 4 or 5 inches of the top
in flow of water comes post skimmers/reactors/been fully filtered and may use a 5 micron sock prefilter
water flow though filter must be slow enough that it does not disturb the sand but fast enough it not allow any detris to collect
bucket needs to be sealed from light so as not to encourage any growths
Requires no sifters, snails, critters, etc. various pods are fine and will be there regardless
requires no maintenance 

bucket DSB's do not operate by breaking down material in the same manner as a conventional DSB but rather operate on the principle of diffusion to feed the bacteria which then the biological processes chemically break the Ammonia, Nitrite and Nitrate to free nitrogen gas. The prefilter is a large part of the long term success of this method.

It is very simple but every aspect of it must be correct to function long term. Well pre filtered, no light, right type of sand, correct flow rate.

So that strained the heck out of my brain but I think I got it right. Actually I'm going to build one. I've never used one and had pretty much forgotten all about them until this post jogged my memory. Does anyone have the article Anthony wrote on them? It was Coral mag sometime 5 to 7 years ago.


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## ReefABCs (Nov 10, 2012)

wildexpressions said:


> for the purpose of convo you need to define whether you are building DSB, a RSDB or a bucket DSB. They are all different and none of them really work well unless you follow pretty specific design/setup.
> 
> The bucket DSB ( I know peeps call it a RSDB but it makes it confusing as there are several types of RSDB's) Anthony's system is very specific and it requires no maintenance and he has had them running as long ass 10 years apparently.
> 
> ...


This is what I was going for, but instead of an actual bucket make a small tank 24x12x12. My thought was for 2 things, A bucket would not be aesthetic in my space and I was not sure if a 5gal bucket alone would be enough to keep Nitrates at zero or close to it.

Where can I find oolitic sand? I checked and Carib sea has it approx. $29 for a 30lb bag how many sq in will that be?


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## wildexpressions (May 3, 2010)

ReefABCs said:


> This is what I was going for, but instead of an actual bucket make a small tank 24x12x12. My thought was for 2 things, A bucket would not be aesthetic in my space and I was not sure if a 5gal bucket alone would be enough to keep Nitrates at zero or close to it.
> 
> Where can I find oolitic sand? I checked and Carib sea has it approx. $29 for a 30lb bag how many sq in will that be?


you should be able to buy that sand at any lfs. I always had bags of it in stock and if they don't have it they should be able to pull you a few bags on their next order with no difficulty.

Don't take my word for my post though. Need to research it and confirm as my memory is not the best. I just wanted to make the point that, as you already knew, these are substantially different animals then a normal RDSB.

I do not remember what he claimed for his average nitrates except it was low enough to grab my interest at the time. I think he talked of a bucket as enough for around a 200 gal tank.

In my shop tanks I placed 5 gal buckets inside of my sumps and filled them full of a variety of media like tiny sea shells producing massive surface area. You can do a lot of stuff with 5 gal pails.

Building in a glass box should not make any difference except for the light issue. Try it and see how it goes. If stuff starts growing then you can cover it you somehow. You might build the glass box out of dark tinted glass.

I'm glad you posted about this As soon as you post the results of your research on oolitic sand, grain size, etc I'm gonna build one


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## wildexpressions (May 3, 2010)

a followup. As I mentioned in previous posts I am now going to set up one of these and so I researched it a little. Here is an excellent post on the topic by Anthony nd it seems my memory was flawed on a at least on important thing, the sand size.



> DSB - Deep Sand Bed Potential
> Anthony Calfo
> Perhaps the most underrated but also the most reliable and significant benefit to a DSB is the ability to reduce nitrates naturally and quickly. Over ten years ago I wrote about hobbyists using a remote DSB (AKA - "RDSB") as a means of addressing the fears that many folks had at the time (and some still do) about "what if" a display DSB gets polluted or goes bad. It is true too; illuminated DSBs are more of a challenge to keep healthy because of the site competition (sand surface) between desirable and undesirable life forms with the increased availability of energy sources (food, waste, light). Yet, most all of the benefits of a DSB can be had with an unlit DSB reservoir that is plumbed inline to the main system. The typical RDSB application for home-sized aquariums (under 800 liters) is a large bucket full of sand (maybe 25 kg of fine sand in a 20 liter bucket) that has a supply of filtered water on a continuing path in the aquarium system. Some folks simplify it even further by sitting their RDSB bucket in an unlit sump and gravity feed water from a display or refugium above&#8230; or even a tee off of the sump pump manifold. The sump RDSB can then gently spill over the sides of the bucket into the open reservoir. It is quite simple and effective for mainataining nitrates below 10 ppm.
> 
> ...


the above excerpt was found at http://forum.marinedepot.com/Topic59558-13-1.aspx


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