SaltwaterNoob17
Reefing newb
How many inches of sand should be in a refugium? Is a deep sand bed recommended?
Refugium: DSB?
- Thread starter SaltwaterNoob17
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Bifferwine
I am a girl
It depends on how much space you have. If your refugium is small, you don't want a DSB because it will just take up too much space.
A DSB should be at least 6 inches deep for it to be effective.
A DSB should be at least 6 inches deep for it to be effective.
Hiker4twenty
Reef enthusiast
What is the advantage of a DSB? I'm going to be upgrading to a larger tank and a larger fuge soon.
Rcpilot
Reef enthusiast
The DSB is where anaerobic bacteria grow. They can break down the nitrate in our tanks. I don't think they actually eat it. They use the O2 molecule attached to the nitrogen molecule for respiration. Once those molecules separate there is nothing left but harmless nitrogen gas. The nitrogen bubbles out of the water at the surface where gas exchange between the water and air takes place. No more nitrates. :mrgreen:
There are concerns with a DSB. There are lots of them, but most are common sense. Don't stir it or use a gravel vac on it. The whole point to the DSB is the bottom layers are left undisturbed so the anaerobic bacteria can grow and colonize the deep regions. If you introduce O2 to that deep region you'll crash the whole sand bed. There's a long list of things that happen in a chain reaction sorta way - the end result is usually a dead tank - just don't stir it.
Another concern is they COULD become a nutrient trap after some unknown period of time. Not WILL become a nutrient trap - COULD become a nutrient trap IF not maintained properly.
So how do you maintain a DSB so that it DOESN'T become a nutrient trap and explode on you at some random time in the future? You keep a good clean up crew. If they are hungry and looking for food - then not much will end up trapped in the sand to rot later. You keep the right KIND of clean up crew. You need sand burrowing critters to constantly turn and sift the upper regions of the sand bed. This helps assure that no detritus is left in the sand bed. These include various snails, crabs and other inverts such as sand sifting star fish.
This is my personal feeling and you won't find it in any books. I'm probably dead wrong, but this is where my brain is at:
I think it's probably a good thing to keep a sand sifting goby in your tank if you plan to run a DSB in the display. They are diggers. They dig deep. They move sand from here to there and back up yonder and down the hill and behind that rock and they dig. Did I mention they dig? They dig.
Right about now you're thinking - but you just said NOT to disturb the DSB and now you're talking about putting a swimming bulldozer in the tank to take care of the DSB by digging and moving sand around. :shock: You said don't stir it!!
Gobys don't rip the whole sand bed apart at once. They do it very slooooooow. It takes them months to work around a tank. Many months if they are small and the tank is large. I think it's probably a good thing to have the sand slowly churned and turned over time. But just a little bit at once. When the goby digs down he is exposing the anaerobic bacteria to conditions they were not meant to live in and they ARE going to die. And when he digs he is burying your surface inhabitants like aerobic bacteria and microscopic pods and other critters and THEY are also going to die. But this is all on a very small scale. It's natural. I don't think it has much impact on the tank in the way of nitrates and I think it is beneficial to keep the sand somewhat aerated over time to prevent compaction and settling.
Some people use what is known as a remote DSB. They put a DSB in a 5g bucket and plumb it into the sump. Now it's removable if it ever causes problems. Just stop pumping water into it and pull the plumbing out. No more DSB.
There are concerns with a DSB. There are lots of them, but most are common sense. Don't stir it or use a gravel vac on it. The whole point to the DSB is the bottom layers are left undisturbed so the anaerobic bacteria can grow and colonize the deep regions. If you introduce O2 to that deep region you'll crash the whole sand bed. There's a long list of things that happen in a chain reaction sorta way - the end result is usually a dead tank - just don't stir it.
Another concern is they COULD become a nutrient trap after some unknown period of time. Not WILL become a nutrient trap - COULD become a nutrient trap IF not maintained properly.
So how do you maintain a DSB so that it DOESN'T become a nutrient trap and explode on you at some random time in the future? You keep a good clean up crew. If they are hungry and looking for food - then not much will end up trapped in the sand to rot later. You keep the right KIND of clean up crew. You need sand burrowing critters to constantly turn and sift the upper regions of the sand bed. This helps assure that no detritus is left in the sand bed. These include various snails, crabs and other inverts such as sand sifting star fish.
This is my personal feeling and you won't find it in any books. I'm probably dead wrong, but this is where my brain is at:
I think it's probably a good thing to keep a sand sifting goby in your tank if you plan to run a DSB in the display. They are diggers. They dig deep. They move sand from here to there and back up yonder and down the hill and behind that rock and they dig. Did I mention they dig? They dig.
Right about now you're thinking - but you just said NOT to disturb the DSB and now you're talking about putting a swimming bulldozer in the tank to take care of the DSB by digging and moving sand around. :shock: You said don't stir it!!
Gobys don't rip the whole sand bed apart at once. They do it very slooooooow. It takes them months to work around a tank. Many months if they are small and the tank is large. I think it's probably a good thing to have the sand slowly churned and turned over time. But just a little bit at once. When the goby digs down he is exposing the anaerobic bacteria to conditions they were not meant to live in and they ARE going to die. And when he digs he is burying your surface inhabitants like aerobic bacteria and microscopic pods and other critters and THEY are also going to die. But this is all on a very small scale. It's natural. I don't think it has much impact on the tank in the way of nitrates and I think it is beneficial to keep the sand somewhat aerated over time to prevent compaction and settling.
Some people use what is known as a remote DSB. They put a DSB in a 5g bucket and plumb it into the sump. Now it's removable if it ever causes problems. Just stop pumping water into it and pull the plumbing out. No more DSB.
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Hiker4twenty
Reef enthusiast
Very in depth answer Chris! I'm going to be making another fuge out of my 29g tank and was thinking about going the route of a DSB. I don't anticipate it having any issues as I'm not going to be messing around with it. I just want the best source of filtration I can have within my $ limits. If a DSB will help with my filtration then I will do it. If its not really that much more beneficial then I say the hell with it.
Rcpilot
Reef enthusiast
I make sure I have a DSB SOMEWHERE in the system.
On my 30H display there is a CPR HOB refugium and I have a 6" DSB in there. There is also about 5-6" in the aquarium since it's so tall.
I had a HOB fuge on the 10g frag tank and kept a DSB in that fuge as well
I now have an entire 20H dedicated to my fuge on the new 29g frag tank. Thjat 20H tank has 70lbs of fine aragonite sand. It's about 7" deep. With a separate 20L sump for my return pump and skimmer.
I believe in my heart that DSB work so I use them on each tank. Doesn't have to be an enormous sand bed. Doesn't have to be 15 square feet of sand bed 12" deep to become effective. Any pocket of sand thats at least 6" deep and 12 square inches is enough to have some benefit IMO.
Some people would say that you need a certain amount of square inches or feet of surface area for a DSB to become effective. If that was true it wouldn't work in a 5g bucket. Whats that? maybe 150-200 square inches of surface area? 1sq. ft? Now consider the amount of nitrates I probably have in the 30 display - not that many. There's very little bio load in the tank. So the relatively small DSB in the HOB refugium is more than adequate. I used to think I needed the entire 24x12 DSB in the bottom of the tank. I don't believe that anymore. There's not enough bio load to even feed that entire DSB.
Same with the DSB in the HOB fuge with the 10g tank. 6" deep and probably 3" wide x 10" long. 30 square inches of surface area - but how many nitrates do you have in a 10g frag tank full of frags and one little fish? The relatively small DSB in a simple HOB fuge is adequate for nitrate reduction in that situation.
On my 30H display there is a CPR HOB refugium and I have a 6" DSB in there. There is also about 5-6" in the aquarium since it's so tall.
I had a HOB fuge on the 10g frag tank and kept a DSB in that fuge as well
I now have an entire 20H dedicated to my fuge on the new 29g frag tank. Thjat 20H tank has 70lbs of fine aragonite sand. It's about 7" deep. With a separate 20L sump for my return pump and skimmer.
I believe in my heart that DSB work so I use them on each tank. Doesn't have to be an enormous sand bed. Doesn't have to be 15 square feet of sand bed 12" deep to become effective. Any pocket of sand thats at least 6" deep and 12 square inches is enough to have some benefit IMO.
Some people would say that you need a certain amount of square inches or feet of surface area for a DSB to become effective. If that was true it wouldn't work in a 5g bucket. Whats that? maybe 150-200 square inches of surface area? 1sq. ft? Now consider the amount of nitrates I probably have in the 30 display - not that many. There's very little bio load in the tank. So the relatively small DSB in the HOB refugium is more than adequate. I used to think I needed the entire 24x12 DSB in the bottom of the tank. I don't believe that anymore. There's not enough bio load to even feed that entire DSB.
Same with the DSB in the HOB fuge with the 10g tank. 6" deep and probably 3" wide x 10" long. 30 square inches of surface area - but how many nitrates do you have in a 10g frag tank full of frags and one little fish? The relatively small DSB in a simple HOB fuge is adequate for nitrate reduction in that situation.
