using a Plenum in a aquarium

[darklcd]

good day all

I am not sure if I am in the right area but I hope so. I was looking at a few things online and I see that there are a few people that use plenums to help with filtration and more so in the denitrification process and I was wondering if any one has any info or experience with them or how to set one up.

thanks

 

[Krish]

Here's an older thread on plenums

http://www.reeffrontiers.com/forums/showthread.php?t=9818&highlight=plenums+wasting+options

 

[riemannp]

For what it's worth: there is an article in the 2007 annual Marine Fish and Reef Magazine called "Plenums A Path Toward Thriving Tanks". This article states "A plenum is a void space created in the Jaubert system by placing a perforacted plate 1 inch or so off the bottom of the aquarium" I had always thought a "plenum" was simply whatever you used for bottom rock, substrate, etc.

 

[Gimpster]

GARF uses them as part of their Bullet Proof Reef setups and has instructions on how you build and use them.

 

[darklcd]

I had a look at the GARF instructions and they look simple enough to do I am just wondering if they would work as well as they say or if its a waste of time to take all my sand and rock out to do it

 

[mojoreef]

Darcklcd using sand kind of defeats the purpose of a plenum. The plenum is designed to use larger substraight which helps with diffusion. See when you use fine sand the anarerobic zone (where your denitrification occurs) ius just under the top layer of sand (half inch). Products (detritus/food/waste and so on) lands o top and is reduce by bacteria and then diffused via bacterial biofilm to the bacteria below. In a plenum the concept is to keep the whole substraight aerobic (oxygenated). To do this they use larger particles (about 5 time the size of gravel) and then promote high flow, this high flow mechanically diffuses the water through the substraight (thus keeping it oxygenated and aerobic). The section below the substraight is protected by a screen system and stops the flow of oxygenated water from reaching it, this area becomes anaerobic and houses the anaerobic bacterai for denitrifing.
The problem with plenums and other substraights systems is that they become riddled with ammonia, this ammonia stops the release of the first enzyme that is usd by bacteria to perform denitrification. So what the bacteria does instead is to convert it to ammonium and send it back into cycle.


Mike

 

[Skimmy]

if you were building a new house, would you put the organtic wastes from the inhabitants underneath your living room/bedroom??(plenum)
no, you would flush them down the toilet...(skimmer)

as you can see, i dont care for plenums, and that's why

 

[ichthyoid]

Plenums-my experience

I once set up a 125 with a plenum, dual overflows, skimmer, small carbon use in an Eheim cannister, 12 x 36 inch T8 HO flourescents (no, not VHO's)- 6 rows custom designed and built by myself, about 100 or so pounds of live rock with aditional base rock added for the foundation. I used a Mag 1200 with a sump and custom designed filter built myself. Added (over a years time) about 12 -15 small to med size fish like wrasses, damsels and anthias, 27 LPS corals. Another two dozen or so inverts. including hermits, coral banded shrimp, cleaner shrimp, blood shrinp (ouch), etc. It was beautiful. Everything seemed fine for about 2 years. I dosed with Kent 2 part, magnesium, strontium, iodine, etc. and performed small monthly water changes (20 gal.). I fed my corals individually with a syringe feeder with a rigid airline extension, and they grew.

Then one day my wife called me on my cell in a panic. She said everything was dying. I raced home (after telling her what emergency measures to take). I got there from 2 states away in under 6 hours. I discovered that my Australian sea apple had croaked and started taking everything else with it in a domino fashion (they release a neurotoxin when stressed or dying, which I did not know at the time). A sort of slow motion system crash ensued (over 24 hours), that despite extreme effort and extensive knowledge, I could not prevent. I learned 2 very important things. 1) Never keep a sea apple in a tank with anything else you don't want to lose. 2) 'IF' I ever use a plenum again, it will be placed in an external sump/tank that I can isolate and work on if needed. During the emergency, I discovered that I was unable to change and/or filter the water under the plenum. I don't know if the sea apple caused it all, or the plenum did. I tend to believe the former, based on others' experiences. Personally, I now use deep sand beds. I have gone diving in half the worlds oceans and can't recall once seeing a plenum in any of them. Deep sand beds are ubiquitous.

 

[ichthyoid]

Ps-

If you want to enhance denitrification, I suggest mixing up some calcium acetate and adding it to your top off water (if you have a fair amount of live rock especially). It is inexpensive, easy and safe. It works and solves several problems simultaneously with no negatives that I have found or read about. Too few people understand the chemistry AND biology well enough to make an informed decision IMO. I have studied this and the 2 part methods. I find this one superior with the extra benefits of enhancing denitrification by introducing organic carbon into your system and reducing phosphate too!. If you run a denitrifier you can potentially use this to 'feed' your unit. Be careful and make sure you understand what you are doing. Don't just dump a bunch in and wait to see what happens. Check out this article for details:

http://www.reefscapes.net/articles/breefcase/kalkwasser.html

 

[stonycorals]

Wow talk about anecdotal evidence. Dr Jean Jaubert does use more of a gravel-sized substrate for his systems. However, Delbeek had set up a large system at the Waikiki Aquarium that employed smaller grained sand and was quite successful at maintaining near NSW nutrient levels despite the addition of inorganic nutrients via the well used.

There is no question that plenums work and work well. Much like DSBs, plenums have been imcorrectly blamed for tank crashes, when in reality it is typically the fault of the aquarist.

There is a slight but important correction to make to what mojo said. The reason that plenums work isn't due to waer being forced mechanically through the sand like that of an undergravel filter, its simply concentration gradients.

Lastly, due to active biological processes sandbeds (plenum or DSB) does NOT become a nutrient sink.

 

[stonycorals]

Incidentally, many including Dr Jaubert, Calfo, Delbeek, Sprung andany others (including myself) successfully used plenums for over 7 years.....

 

[burning2nd]

is this a under gravel filter where talking about?

Plenum's to me are the think thats attached to the lower intake manifold on a car........

what are we talking about?

 

[stonycorals]

No, we're not talking about undergravel filters... Plenum systems, in an aquarium, not a car.

 

[burning2nd]

ok well thanks for explaining that one.....

ne1? else
plenum

 

[stonycorals]

There was a link on the first page. If you have RA1 or RA3, they talk about plenums. Also called the Jaubert or Monacco method, even Natural Nitrate Reduction method. Created and patented by Dr Jean Jaubert of the Monacco Aquarium. It's similar to a DSB whereby a 4" sand bed sits on over a screened partition that is perforated (think eggcrate) which is suspended over 1" of water, a void or plenum. Due to the thickness, the plenum part is a low oxygen environment resulting in bacteria strain development that includes denitrifiers. So a high oxygen environment is above a low oxygen environment. There is diffusion that happens across the sand bed that reduce NO3 -> NO2 -> N2 and can result in the reduction of PO4 as well.

 

[Curtswearing]

I personally find the plenum to be superior to a DSB but that's just my opinion. I won't use either though in anything other than my mantis tanks....way too much hassle.

I have gone diving in half the worlds oceans and can't recall once seeing a plenum in any of them. Deep sand beds are ubiquitous.

No they aren't ubiquitous. The ocean doesn't work even REMOTELY like our tanks. Dr. Ron led people to believe that the sand near coral reefs and seagrass beds filtered the products produced by the reefs. This is incorrect. In nature they do exactly what they do in our tanks, they are a source of nutrient imports to the reef. Here is one big difference. Sandbeds in nature don't just sit there for years upon years collecting detritus. Storms and tides remove the sand and detritus and send it to the abyssal plains. Then storms and tides send the sand back. It is pretty much a [CTRL][ALT][DEL] of the entire system. Here's how Dana Riddle (yes THE Dana Riddle) wrote about a recent storm.

Aloha,
We can't reasonably simulate a storm (this coming from someone living 150 feet away from a Hawaiian coral reef). Winter is the time for storms on this side of the island. I just recovered the pieces of my data logger instrument housing from an area sheltered from winter swells. This housing weighed almost 100 pounds before it (and its concrete anchor - epoxied to rock 4 feet above the tide line) was ripped up and deposited almost 10 feet above and far away from its original position. Rocks weighing 100's of pounds were also swept away. This lagoon had sand in it before the storm - but no more. But the corals made it through just fine (expect for those washtub sized colonies that were ripped off the bottom). Just wonder how many powerheads it would take to do that?
Dana

Here's what Dr. Ron said about the subject in 2003

The absolute position of the sediments will often vary from season to season, particularly in intertidal and shallow subtidal areas. Tourists who always visit a given resort at a particular time of year are often quite amazed when they return to the resort six months out of sync with their usual pattern and find the sandy beach they expect to see has vanished, leaving a hard coral pavement instead. Movement of sediments is less in deeper waters but it still occurs. In fact, one major characteristic of natural sand beds is their mobility.

http://www.reefkeeping.com/issues/2003-06/rs/feature/index.php

 

[Curtswearing]

There is no question that plenums work and work well. Much like DSBs, plenums have been imcorrectly blamed for tank crashes, when in reality it is typically the fault of the aquarist.

Agreed. However, there are MANY situations where the crash was caused by a DSB/plenum (or I should say a small problem became a big problem due to the DSB/plenum). Dr. Ron can't keep his sandbeds from causing problems, Lee Chin Eng couldn't, Walter Adey certainly can't.....look at one of his latest disasters.

If you squint real hard, you can see hippo tangs in addition to the yellow tangs, dead corals, and algae.

There is a slight but important correction to make to what mojo said. The reason that plenums work isn't due to waer being forced mechanically through the sand like that of an undergravel filter, its simply concentration gradients.

concentration gradients is pretty much the same thing as diffusion.

Lastly, due to active biological processes sandbeds (plenum or DSB) does NOT become a nutrient sink.

You might want to let Dr. Ron know this.

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Having a 60 gal remote DSB may work, some folks can pull it off. I suspect, however, in most cases these turn into nutrient-sinks and will be problems in the long run.
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It really matters because that is why a sand bed works. The material once captured by the animals in the bed really never leaves the bed. It cycles over and over in the bed from one organism in close proximity to another until the energy in it is used up and the material in it gets exported. The decoupling of these reactions allows the material to be liberated into the tank water where it will be food for, primarily cyanonbacteria, but other microalgae as well. [/B]--------------------------------------------------------------------------------

When asked about flow issues due to blowing sand

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As an example of the flow necessary to move materials out of an "Acropora" thicket in nature, the flow across such a region has been measured, In the volume of a 100 gallon tank, that amount of flow would be on the order of 50,000 gallons per hour....
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heres a good one on your will last forever quote

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The added feeding goes to maintain the DSB that would have been adequate if it were in the main tank. However, in this case, you have added more nutrients to the system and as the DSB is a finite system it becomes saturated and will not be able to export them adequately.
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when asked what kind of tank a dsb would support

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There is no magic number per gallon, but the actual number of fish per unit volume is pretty low. Probably on the order of no more than 3 or 4 relatively small fish per hundred gallon volume. Similarly coral diversity and abundance is pretty low. --------------------------------------------------------------------------------

but he does let us know its simple

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If the hobbyist can't maintain a DSB in the main tank, which is about as easy as falling off a log, they shouldn't really try to maintain one in remote tank, but should probably try to use some other sort of filtration.
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but then 4 days later

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It is interesting that people tend to think that all of this is supposed to be "simple" and "easy" to do. Most folks don't realize that a coral reef ecosystem is the most complicated ecosystem on the planet, and that the sand bed component to it is also complicated. The level of complication is here is orders of magnitude more than is found in any manmade object, structure, or construction.
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Personally, if I was culturing corals for reproduction I wouldn't use a sand bed.
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When asked how many detrivores to add to a DSB Ron says

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The maximum amount of the most you can maintain.
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but then 2 days later in the same thread

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In my advice I generally tell people to add as little as possible, as that is the cost effective way.
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Heres a little help for folks on what and how many kinds of critters you need

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A DSB needs around 200 species to function properly and most land-locked reefers can't get the diversity high enough with just the detritivore kits and seeding with "live sand". The "Southdown and Seed" method is quite common and I doubt many of these tanks ever reach the diversity level required to function as envisioned. A DSB can be handicapped right out of the gate by lack of diversity.
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[stonycorals]

Curt,

Thanks for the info.... I agree, DSBs and plenums function differently than "comparables" from the oceans.... I totally agree that Dr Ron was way off on his sentiments comparaing seagrass beds to plenum/DSBs... But what we (aquarists) do via protein skimmers, DSBs/plenums, powerheads, etc are ALL approximations of what the oceans/reef do, albeit our methods are so much less efficient! Though I try to use Carlson Surge Devices for my coral prop systems (some which include DSBs, plenums, and Zeovit) as a more efficient method than powerheads.

You mentioned Dr Ron, Eng, and Adey, but I didn't specifically mention them for a specific reason, especially the later two, Eng and Adey's methods are far from the plenum and vary from DSBs. Adey has his ATS, and Eng has his 'miracle mud' which aren't the same as a plenum, nor a DSB. These represent variables which would skew any deduction you could make about DSBs.

I've seen the Monacco aquaria, and when I have set up Jaubert/plenums in the past, I don't have nearly the same amount of live rock as a comparable Berlin. Again, I've had systems run for about 7 years myself, with near NSW levels of NO3 and PO4 as measure by a hanna.

I won't address much of your quotes as they are Dr Ron talking about DSBs while the original poster inquired about DSBs. Again, I've run DSBs for 3-4 years with low nutrient levels. As far as nutrient sinks, the only potential nutrient to potentially accumulate would be those that are P based as denitrification eliminates the NO3 as N2. However, P is a requirement for all living things, and due to limited hobbyist testing for organic forms of phosphorous, this IS subject to speculation.

Some of the quotes are incomplete, such as the one about not recommending a DSB for a system that cultures coral. Why? I do use that for one sps culturing system, it's been running for only 1 year so it's early to tell...

As for requiring 200 species, yeah, I don't know where anyone could possibly state this, unless one has the time, equipment, and know how to identify species of bacteria What about the diversity offered by adding live sand and live rock?

This is a hobby, and there are quite a few "gurus" out there. We need more intersection of the scientific community with our hobby. This is one of the chief reasons I included Jaubert as a source, his papers are scientific in nature and subject to peer review. I've a lot of respect for the Europeans as they seem much further in their "skills" of this hobby. Whatever happened to Fossa and Nilsen, they're great examples of bringing the hobbyist thought with scientific research. I also have a lot of respect for Delbeek, Carlson, etc....

 

[burning2nd]

i woulder how a system would handle have

a main tank, connected to a Sump also a connected to another 2 tanks
one like a refugm and the other like this Plenum....


best of both worlds?

 

[Curtswearing]

NOTE: I WANT TO POINT OUT THAT I'M NOT ANTI-DSB ALTHOUGH I DO HAVE A PREFERENCE FOR SHALLOW SAND BEDS AND BARE BOTTOMS.

Thanks for the info.... I agree, DSBs and plenums function differently than "comparables" from the oceans.... I totally agree that Dr Ron was way off on his sentiments comparaing seagrass beds to plenum/DSBs... But what we (aquarists) do via protein skimmers, DSBs/plenums, powerheads, etc are ALL approximations of what the oceans/reef do, albeit our methods are so much less efficient! Though I try to use Carlson Surge Devices for my coral prop systems (some which include DSBs, plenums, and Zeovit) as a more efficient method than powerheads.

I agree. Especially about the Carlson Surge Device. I know someone who didn't run his for a couple of years and then he finally started up again. He saw his SPS corals really explode afterwards. Personal note: NaH2O, Mojoreef, MtnDewMan and I got to eat dinner with Bruce Carlson a couple years back and he's one of the nicest guys you would ever meet.

You mentioned Dr Ron, Eng, and Adey, but I didn't specifically mention them for a specific reason, especially the later two, Eng and Adey's methods are far from the plenum and vary from DSBs. Adey has his ATS, and Eng has his 'miracle mud' which aren't the same as a plenum, nor a DSB. These represent variables which would skew any deduction you could make about DSBs.

When speaking of Lee Chin Eng, I wasn't talking about Leng Sy who invented the Ecosystem Miracle Mud filtration method. Lee Chin Eng actually preceeded all of the current promoters of NNR by a good 40 years. Google him....his story is quite interesting.

However, your point is absolutely correct and taken. The systems are different. Newer people won't know this but Dr. Ron's recommendations are POLAR OPPOSITES to what Jaubert would recommend. Newer people to the hobby unfortunately missed the Bob Goemans/Dr. Ron Battles....now those were entertaining. Bob was pro-Jaubert Plenum and Dr. Ron was pro-DSB. (If you want to get technical, Dr. Ron was pro-Dr. Ron.....if he farted, you were lucky if you got to smell it. )

I've seen the Monacco aquaria, and when I have set up Jaubert/plenums in the past, I don't have nearly the same amount of live rock as a comparable Berlin. Again, I've had systems run for about 7 years myself, with near NSW levels of NO3 and PO4 as measure by a hanna.

NNR is taking care of the Nitrates and the orthophosphates are being sunk in the nutrient sink (for now). I've run DSB's as well for quite some time with similar results. My following post will give some of my basic opinions on them.

I won't address much of your quotes as they are Dr Ron talking about DSBs while the original poster inquired about DSBs. Again, I've run DSBs for 3-4 years with low nutrient levels. As far as nutrient sinks, the only potential nutrient to potentially accumulate would be those that are P based as denitrification eliminates the NO3 as N2. However, P is a requirement for all living things, and due to limited hobbyist testing for organic forms of phosphorous, this IS subject to speculation.

Some of the quotes are incomplete, such as the one about not recommending a DSB for a system that cultures coral. Why? I do use that for one sps culturing system, it's been running for only 1 year so it's early to tell...

As for requiring 200 species, yeah, I don't know where anyone could possibly state this, unless one has the time, equipment, and know how to identify species of bacteria What about the diversity offered by adding live sand and live rock?

No worries. This is nothing but the good doctor inventing facts yet again. You need bacteria and you need bio-turbation from some larger species of benthic critters....nothing more. DON'T GET ME WRONG, I RESPECT HIS AMAZING KNOWLEDGE OF CREEPY-CRAWLIES CRITTERS. HOWEVER, I DON'T RESPECT HIM WHEN HE SPOUTS OFF ABOUT THINGS OUTSIDE HIS FIELD OF EXPERTISE WHICH, UNFORTUNATELY, IS QUITE OFTEN.

This is a hobby, and there are quite a few "gurus" out there. We need more intersection of the scientific community with our hobby. This is one of the chief reasons I included Jaubert as a source, his papers are scientific in nature and subject to peer review. I've a lot of respect for the Europeans as they seem much further in their "skills" of this hobby. Whatever happened to Fossa and Nilsen, they're great examples of bringing the hobbyist thought with scientific research. I also have a lot of respect for Delbeek, Carlson, etc....

AMEN!!! Since this was in the Advanced Forum, I thought I would throw up a post that would trigger not only emotion but also thinking (as opposed to merely copying and pasting what other guru's have said).