Plenum theory and practicality

[Witfull]

Originally posted by Reef Geek

Speaking of plenums. Wouldnt a plenum have the same problems as a DSB, no/minimal transport out of the system? Can someone please explain how a plenum works on both a physical construction & installation layer (how it works) and on the chemical layer (why it works)?

since ReefGeek isnt here to start it, ill get it going. in my reef i have a patial plenum due to it being a bowfront. i built it out of eggrate and 1/2"pvc. it stands approximately 1" tall covered in fine mesh nylon screen. i added approx 1" of sand over it then laid another layer of screen on top of it. then laid another layer of sand and agronite over it appox 2".

there are many sites describing the basic consruction of them just google "plenum+reef"

now here ya go big dawgs...break it down

 

[ReefLady]

Moving to "new frontiers" even though this frontier is older... still outside the mainstream.



T

 

[mojoreef]

Arent plenums supposed to be large gravel??? or has something morphed and I missed it again

MIke

 

[wooddood]

that was my beleif too mike,guess ive got some reading to do.

 

[Reef Geek]

Thanks for starting the thread Wit. Last SCMAS (local fish club) meeting some discussion was made about plenums and I was quite interested. But I aint no fool and I never believe just one source. So I want to hear from the knowledgeable and experienced RS elite about their plusses and misuses of a plenum.

Wit, since you got a plenum, how do you like it? Working well?

 

[Curtswearing]

Just to throw this info out there, I believe that Craig Manoukian also has a plenum.

 

[Witfull]

so far (one year on this tank) everything is good. years ago i had one on a fresh water tank and it worked out great., my discus and uaru's bred, neons and cardinals glowed. aneus cats bred. that wass my judgement of success.

 

[ScottT1980]

I have a plenum as well...can't delve into the details as of now because I have to go somewhere tonight...

GARF sort of was my inspiration and I just took off with the idea. The biology/chemistry made sense to me and I knew others that had been succesful with them. I must say that I do not have the "Monaco" system only because I have also incorporated a fuge in with the plenum.

I will check back later on tonight on in the AM to see where this thread goes

Take er easy
Scott T.

 

[Witfull]

Originally posted by mojoreef
Arent plenums supposed to be large gravel??? or has something morphed and I missed it again
MIke

the reason for the different sizes of sands and agronite, is so that the further you go deeper into the bed the tighter the flow is through the grains. also the smaller the grain the more surface area for bacteria to grow. (same principle as a DSB) the 1" of finer sand is a tight zone above the plenum. allowing more anaerobic bac to grow. the layer of screen is to prevent burrowing critters from stirring this zone. the higher lever continues this zone but some critters will penetrate it. the larger agronite will mix somewhat with the sand filling the gaps. then the top layer of agronite is to allow 02 to flow through this level and as a decorative non-sandstorming surface.
i dont know all the science behind it but have had short term success in the time that i have had it on my reef.

 

[mojoreef]

Yea Wit this is a different system that what I am familar with in regards to plenums. I ran a plenum on a tank for several years with no problems, but it was a different animal then what you are discribing.
The plenum had black acrylic sides (to keep light out) and a mesh top simular to what you discribed. But on top was very coarse gravel. I would say three to four times as thick as CC. and it was about 4 inches high in total. Water flow was directed at the plenum and it kept the whole 3 inches of gravel areobic (well oxygenated), lots of bugs and life, moderate dentirification, and an ammount of elemental replenishment. This plenum was taken off Jauberts Plans (him and another fellow invented it)

The system you are discribing sounds like a blend of the plenum and DSB concepts, so I would imagine that it would have all the goods and all the bads of a dsb. One thing that seems to be fixed possibly is the flow restrictions a DSB has.

not much help but best I got my friend


MIke

 

[tankgirl]

Hi Wit, you might want to browse this thread on plenums;
http://www.thereeftank.com/forums/showthread.php?s=&threadid=26603

 

[Imperial]

This might be a stupid question but here it is. What is the diffrence between a plenum and an undergravel filter without the power heads?

 

[ScottT1980]

Not a dumb question at all...It is pretty much the same exact thing. In fact, I was going to use an undergravel filter for my plenum but opted for just PVC and screening mesh instead...

Take er easy
Scott T.

 

[ScottT1980]

TG, thanks for the link (and the links within the link and the links within the links within the link ). The information provided pretty much explains a good bit about the pros/cons of plenums.

The only thing I question is my use of substrate size on top of the plenum. I did not carfeully plan this out and therefore, I think the function of plenum is hindered a bit. I will try to take a picture of my DSB just to show you how deep it really is with the plenum (another con, you lose a lot of vertical space).

It is like everything else in this hobby. I know people who swear by them and I know people who would rather go the DSB route (or other routes). THere is always more than one way to skin a cat.

FWIW, I think all of the GARF tanks are run with a plenum, just another example of success with this setup...

Here is a very long thread where the subject was debated ad nauseum on RAG. With the links provided you should have enough reading to last a LOOOONG while...

Take er easy
Scott T.

 

[mojoreef]

Oh man I remember that one Scott, did I ever get in trouble for that one.


Mike

 

[Witfull]

i haven finished all the links in the threads, and for the life of me and wearing out google, i cannot find the pages i researched plenums on with the setup that i have. i thought it was Albert Thiel, but cannot find it. i guess mine is a modified plenum/DSB. alother grand experiment in Reefing. in the bow area of the tank its strickly DSB 4" deep. but in the rectangular area its the mod plenum. at 1" plenum, 3' sand mix.
we shall see......tbc

 

[mojoreef]

No matter Wit. Thier is nothing wrong with your system, it is what it is. Thier are so many modifications to so many different fitration systems only God really knows for sure .
IMHO I would look at your system as a DSB system, with possibly a little better elemental replenishment. With your system I would make sure that you keep you areobic zone well oxygenated, as in dont reply totally on bugs, a gentle stir a syphoning of the detritus that comes from it will really enhance its working ability and will give you a longer life span.
I am not saying to syphon the sand (dont do that) stir it gently with your fingers (or anything really) and then have the syphon about and inch or so away to suck up the sludge.

anyway my friend thats what I would do.

Mike

 

[Scooterman]

I remember way back when I was FW, about 25 years ago I started a 20g FW set-up, it had an undergravel filter with course rubble bed & two inlets pumping air down there to create a suction forcing circulation through the bed. I had this one tank about 5 years when one day lost power, system upchucked & a big Crash! I then seen system pumping water creating a reverse flow through the bed but eventually the same problem occurred about the same amount of time. I eventually threw it all out & went to a vacuum method as I do now. That setup with a small canister filter went on about fifteen years without problems. I then merged to SW started with a 2" bed in a 30g, then merged to 100g tank with 4" to 6", after reading months in months went to a rubble base naked underneath. So I guess my point is, with any luck in ten years from now, I'll post the results!

 

[jks1]

I have sort of a modified plenum in mine. This 29 has only been up for a few months, but i ran a 75 FOWLR in Calif for a couple of years with the same setup. I raised some eggcrate on 1" PVC pipes and covered w/ fiberglass screen. Added about 1 inch of caorse cc on top then 1" of LS on top of that. I ommited the layer of screen between the diff substrates.

 

[Flatlander]

Hmmm, I seem to recall something about that link also.