KENT refugium substrate

[MarkD40]

I am setting up a 20 gallon refugium for macroalgae and pods. I am putting in a DSB. I was reading about KENT refugium substrate. It is a dark gray color and appears to be very fine in texture. I do not plan on having really strong water movement in the fuge.

Has anyone had experience with this product? I was also wondering if I used sand with it should the sand be on the bottom of the DSB, on the top, or mixed in with it? (I want to use sand so I don't have to buy as much of the KENT substrate) Thanks!

 

[oct2274]

i'm curious to this as well.......

 

[doox00]

I do not know what substrate to put into my fuge yet. its just barebottom now with a few pieces of live rock and a small ball of cheato. I have southdown in my tank, I was going to put a dsb in my fuge with that, but its so fine I do not want to risk it being all over the place and getting into my return pump.

 

[MarkD40]

^

 

[bertoni]

A DSB isn't going to function in a refugium, not of that size, anyway. You could add a thin layer of sand to grow certain types of animals, or a thin layer of live rock rubble for others. I don't have any substrate in my refugium, although I have a couple of pieces of spare live rock.

 

[MarkD40]

Why won't a DSB work in a refugium? I have been reading about remote DSB's and have never heard that they don't work. How do the bacteria know that the DSB is too small?

 

[Amphiprion]

A typical refugium does not have the surface area to properly support enough infauna (small animals, not necessarily bacteria) to keep a sand bed "healthy." The reason for this is that they only seem to like the open section of the tank surface area, as they avoid corners. In addition to that, DSBs need very good flow all throughout the tank--so making less flow is not a good idea. I am not a proponent of the reverse DSB, but the main reason it is different is because water is forced to the surface from beneath (quite a different scenario altogether).

 

[MCary]

I use KENT, seems to be good stuff. For a DSB the grain size seems to be the most important thing. Need to be at least 3" deep. 4" or more recommended. Not really clear on the fauna's function in the DSB. Has to do with stirring and turning over the surface layers. All I know is that the bottom must be anaerobic. There are some that are experimenting with keeping a DSB in a bucket, kind of a remote DSB. Not sure what a reverse DSB, as AMph describes it it sound like a fluidized bed sand filter which is not DSB becuase the water flowing up from below would oxygenate the sand ruining the anaerobic layer.

 

[Amphiprion]

From what I understand (as I thought the same thing as MCary when I first heard it), the upward flow is very, very slow.

 

[bertoni]

The remote refugiums have two issues: getting the food there, and keeping a suitable infauna population going. The DSB processes mostly solids, and most tanks don't have enough circulation to move the detritus to the refugium.

Also, while bacteria do a lot in a DSB, the infauna are responsible for most of the transport. In a small bed, the animals won't function properly. www.ronshimek.com is one resource for more information, and the invertebrate forum has lots of threads on this topic as well.

Another issue would be that the refugium would need to be close to the size of the main tank to accomplish much.

 

[MarkD40]

Thanks jb,
I have a 75 gallon sump with a DSB that I keep in the dark. I want the refugium mainly to grow macro to consume nitrate and feed my tangs. I was wondering if enough detritis would get to the refugium to support pods and you answered my question (NO). Would a DSB in a 20 gallon provide any benefit at all? Supposedly the KENT refugium substrate has much trace elements that get released into the water column over time. If what you are saying is true than I guess just going bare bottom with live rock is all I need.

 

[reverendmaynard]

Remote DSBs do not have water flowing up, down, or around the sand, only over the top. The theory behind it is if you keep the input water as clean as possible, and keep the flow rate high enough that no debris will settle in/on the sand, you don't need the infauna to deal with detritus. Only liquid wastes are processed and only by bacteria. Also, if it evers becomes "saturated" to the point where it stops working or starts leaching back anything, you simply take it off line and either replace the whole unit, or just the sand. This is easy because they are cheap and easy to make and you don't have to worry about any animals in it you want to keep. You can even use more than one so that you can stagger their replacement. There's a pretty comprehensive thread on it in the All Things Salty forum.

You cannot achieve those conditions in a refugium, so it is probably not a good idea to attempt to keep a DSB in one, unless it's very large.

 

[bertoni]

The Kent substrate will likely release iron into the water column. On the other hand, for about $15 or so, you can buy enough iron supplement to last a very long time, and you won't have to deal with mud.

A living DSB isn't going to be useful in a 20g size. The DSB that reverendmaynard is discussing is often called a DSB in a bucket, and doesn't work the same way at all. There's a link to a thread on that topic in the "Introduction to Substrate Choices" sticky at the top of the forum.

You'll find that a lot of animals will grow in the refugium, especially if you feed some phytoplankton. The various algae and photosynthetic microbes can support a lot of animals, too.