Can u use a under graver filter in a reef setup ?
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I'm sure it's possible if you use CC rather than sand... the issue with that would be the risk of it becoming a 'nitrate factory'. UGF's are primarily a biological filter, though they do offer mechanical filtration via the substrate. Once all that collects in the substrate, it would lead to nitrates if not cleaned VERY often and VERY thoroughly. Bad idea IMO
robert
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Run in the traditional manner, where water is drawn down through the sand bed is probably not a good idea. It will concentrate organics beneath the filter plate and either become a nitrate source or worse, if flow fails - could result in an anaerobic explosion poisoning the tank.
Run in reverse however, where clean water is forced down under the filter plate and percolates up through the sand bed, they can be quite useful, and are probably the easiest, most fool-proof, way to run with substrate. The reverse flow will greatly minimize or eliminate dead zones in the bed.
In my system, I have a grid of drilled 1/2 inch pvc on the bottom of the tank. On top of this I have egg crate. On top of the egg-crate I have fine screen. I have several inches of substrate over the screen. Return water from the sump (1325 gph - nominal ) is piped down under the sand bed and flows up through the substrate - keeping the sand bed highly aerobic. To clean my substrate, I simply stir, the water coming through pushes the detritus into the water column where some settles back and the overflows take out the rest. The corals, especially brains love this.
The way I run my tank, I try and keep anaerobic zones minimized in the display. I try and keep the display as aerobic as possible. I have an external anaerobic zone (a five gallon water jug) where de-nitrification takes place.
So, a traditional under-gravel, no. A reverse-under-gravel (egg-crate and screen over the plate) - works nicely - at least for me.
Run in reverse however, where clean water is forced down under the filter plate and percolates up through the sand bed, they can be quite useful, and are probably the easiest, most fool-proof, way to run with substrate. The reverse flow will greatly minimize or eliminate dead zones in the bed.
In my system, I have a grid of drilled 1/2 inch pvc on the bottom of the tank. On top of this I have egg crate. On top of the egg-crate I have fine screen. I have several inches of substrate over the screen. Return water from the sump (1325 gph - nominal ) is piped down under the sand bed and flows up through the substrate - keeping the sand bed highly aerobic. To clean my substrate, I simply stir, the water coming through pushes the detritus into the water column where some settles back and the overflows take out the rest. The corals, especially brains love this.
The way I run my tank, I try and keep anaerobic zones minimized in the display. I try and keep the display as aerobic as possible. I have an external anaerobic zone (a five gallon water jug) where de-nitrification takes place.
So, a traditional under-gravel, no. A reverse-under-gravel (egg-crate and screen over the plate) - works nicely - at least for me.
redtop03
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+1 on a reverse flow UG filter.....PaulB has been running his tank for about 40 years that way...
robert,I'd love to have a RFUG system in my tank like you have yours,if I ever have to take the tank down for whatever reason,I will build mine like you described yours before the tank is set back up
robert,I'd love to have a RFUG system in my tank like you have yours,if I ever have to take the tank down for whatever reason,I will build mine like you described yours before the tank is set back up
robert
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Yes, I decided to go this route after many months of struggles with my substrate (in my 50g) and after reading some of PaulB posts. When I got my 115g the first ting I did was to add the RFUG. Three years later the area under the egg-crate is still clean (I can actually look under it).
When I first set this up I didn't run a sump, I used power-heads to drive the flow under the substrate, had a hang-on-the-back skimmer and a canister filter and the tank just worked. I know there are many ways to run a tank - but I really credit the RFUG for adding an element of robustness to the set-up. It makes it harder to screws thing up, if you know what I mean...
When I first set this up I didn't run a sump, I used power-heads to drive the flow under the substrate, had a hang-on-the-back skimmer and a canister filter and the tank just worked. I know there are many ways to run a tank - but I really credit the RFUG for adding an element of robustness to the set-up. It makes it harder to screws thing up, if you know what I mean...
redtop03
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I like the fact that there is water flow through every inch of the tank that way,even though flow may not be too strong in some places,there's no completely dead spots....
anaerobic areas can be created somewhere else,such as a remote deep sand bed in a bucket,or by using a denitrator....I don't think the DT is the place for it,it's just too hard to service a deep sand bed inside a DT without messing something else up,and you run the risk of stirring up something that will wipe out an entire tank
Paul B
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I don't want you guys installing reverse UG filters. I like having the oldest tank on here.
beaslbob
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+1
Paul know best.
IMHO a tank with sufficient macro algaes will have no measureable nitrates nor phosphates regardless of what else is done. Including UGFs.
my .02
LegoZ81
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The biggest thing people fail to understand is that and wet-dry or flow thru media like this creates nitrAte by design. it's not the build up of organics that cause nitrAte. In a highly oxygenated area with no anaerobic zone the following happens several different strains of bacteria come into play and Ammonia is converted to NitrIte, NitrIte is then converted to NitrAte. The nitrogen cycle ends there if you are running filtration in oxygen rich areas. You then need to do several things to rid the tank of NitrAte, run a algea scrubber (PaulB you do this still right?), run macro filled refugium, run sulfar based dinitrification setup, run remote dsb, or setup some other form of filtration to create and anaerobic area for another type of bacteria to convert NitrAte to free nitrogen which leaves the tank thru gas exchange.
With live rock it is thought that the bacterial film that forms on the rock locally converts Ammonia to NitrIte to NitrAte and then it leaves an anaerobic zone immediately below it that then converts the NitrAte to free Nitrogen. In a DSB it is thought that NitrAte in the water column is converted to Nitrogen in the sand due to the diffusion of water thru the bed.
I think PaulB your success stems from being able to keep organics from building up in the system.
This is the biggest problem with running a DSB, is that when solid organics (which is not NitrAte itself) build up it is VERY hard to replace the substrate as large quantities of Hydrogen Sulfide have built up in the sand bed. to do it properly as much water as possible needs to be drained into a storage tank and all coral fish and rock that is not buried into the substrate need to be removed. It is imperative that this be done without any disruption to the sandbed. you will then need to fill a bucket to rinse any rock that was buried and move it to the holding tank. you will then need to remove 100% of the substrate for disposal and the rinse the tank thoroughly before installing the new rinsed substrate and all of the livestock.
With live rock it is thought that the bacterial film that forms on the rock locally converts Ammonia to NitrIte to NitrAte and then it leaves an anaerobic zone immediately below it that then converts the NitrAte to free Nitrogen. In a DSB it is thought that NitrAte in the water column is converted to Nitrogen in the sand due to the diffusion of water thru the bed.
I think PaulB your success stems from being able to keep organics from building up in the system.
This is the biggest problem with running a DSB, is that when solid organics (which is not NitrAte itself) build up it is VERY hard to replace the substrate as large quantities of Hydrogen Sulfide have built up in the sand bed. to do it properly as much water as possible needs to be drained into a storage tank and all coral fish and rock that is not buried into the substrate need to be removed. It is imperative that this be done without any disruption to the sandbed. you will then need to fill a bucket to rinse any rock that was buried and move it to the holding tank. you will then need to remove 100% of the substrate for disposal and the rinse the tank thoroughly before installing the new rinsed substrate and all of the livestock.
WhoDey
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haha that is classic
robert
Valuable Member
I really can't disagree with anything posted here, but the concentration on nitrate production and elimination is not really the point. I think the role of sulphate is key. In anaerobic zones, sulphate steps into the role of oxygen (an electron acceptor) for organisms (bacteria) breaking down organics.
You can't escape sulphate - behind water and salt - it the third largest component of seawater - so anywhere you have an low oxygen concentration (substrate) you get: Organics + sulphate -> carbon dioxide + bicarbonate + hydrogen sulfide + ammonia + water + phosphate. This has the potential to kill your tank.
Keep it aerobic and you get: Organics + oxygen -> carbon dioxide + nitrate + water + phosphate. In this case, you just deal with the phosphate and nitrate which as everyone points out can be handled in a variety of different ways.
The RFUG greatly reduces the sulphate path of organic decomposition in the main display where it doesn't need to be. In the display sulphate based decomposition is potential source of trouble or worse - disaster.
Perhaps that's the source of PaulB's success? I'm sure there is more to it, but I suspect it plays a fairly big role.
You can't escape sulphate - behind water and salt - it the third largest component of seawater - so anywhere you have an low oxygen concentration (substrate) you get: Organics + sulphate -> carbon dioxide + bicarbonate + hydrogen sulfide + ammonia + water + phosphate. This has the potential to kill your tank.
Keep it aerobic and you get: Organics + oxygen -> carbon dioxide + nitrate + water + phosphate. In this case, you just deal with the phosphate and nitrate which as everyone points out can be handled in a variety of different ways.
The RFUG greatly reduces the sulphate path of organic decomposition in the main display where it doesn't need to be. In the display sulphate based decomposition is potential source of trouble or worse - disaster.
Perhaps that's the source of PaulB's success? I'm sure there is more to it, but I suspect it plays a fairly big role.
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Paul B
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For the past 6 years or so I have an algae filter but for the preceeding 32 years I did not have an algae trough.
My RUGF is run very slow, that is the secret. The areas between the gravel have some detritus and there is very little oxygen flow there. I think that is the reason for no nitrates. That and the water is filtered before it goes through the gravel.
tigé21v
Active Member
How would you go about sizing a RFUG?
Pipe size, # of pipes, hole sizes (are the hole sizes graduated?), flow?
I've got a tank to set up, and have been kicking this idea around since I first brought it into the house.
Pipe size, # of pipes, hole sizes (are the hole sizes graduated?), flow?
I've got a tank to set up, and have been kicking this idea around since I first brought it into the house.
Paul B
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The UG filter is the size of the bottom of the tank, it is a regular fresh water UG filter. Cheap too.
My tank is 6' long and about 14" wide. I have 3 UG filter plates. I piped a 1" tube from each UG filter plate and ran them just above the gravel to one corner of the back of the tank. Fron there the 3 tubes enter a plastic container just above the water. This is the manifold and is there to ensure that each UG plate gets the same flow. I have window screen in it to prevent splashing or noise. In the tank (I have no sump) I have a powerhead which pumps about 500GPH into the manifold which is not a lot of water. About 150 gallons goes down each tube. There must be a filter on the intake of the pump. I have a sponge filter on it because you don't want to pump detritus under the gravel, that would be a disaster. You need to remove that sponge and rinse it out when the flow slows too much. That is the way I have been doing it for 40 years but any way you can get water to run slowly under the gravel will work fine.
My tank is 6' long and about 14" wide. I have 3 UG filter plates. I piped a 1" tube from each UG filter plate and ran them just above the gravel to one corner of the back of the tank. Fron there the 3 tubes enter a plastic container just above the water. This is the manifold and is there to ensure that each UG plate gets the same flow. I have window screen in it to prevent splashing or noise. In the tank (I have no sump) I have a powerhead which pumps about 500GPH into the manifold which is not a lot of water. About 150 gallons goes down each tube. There must be a filter on the intake of the pump. I have a sponge filter on it because you don't want to pump detritus under the gravel, that would be a disaster. You need to remove that sponge and rinse it out when the flow slows too much. That is the way I have been doing it for 40 years but any way you can get water to run slowly under the gravel will work fine.
