Monaco style tanks??

[stringcheese]

Plenum is semi trapped water with near zero oxygen and water flow levels under bed of aragonite that produces denitrafying(nitrate eating) bacterias.
Mine is being built out of fiberglass screen, eggcrate, Beer bottles(for height), and Aragonite.


thanks for the link Doc!

 

[stringcheese]

Plenum is semi trapped water with near zero oxygen and water flow levels under bed of aragonite that produces denitrafying(nitrate eating) bacterias.
Mine is being built out of fiberglass screen, eggcrate, Beer bottles(for height), and Aragonite.


thanks for the link Doc!

 

[stringcheese]

Plenum is semi trapped water with near zero oxygen and water flow levels under bed of aragonite that produces denitrafying(nitrate eating) bacterias.
Mine is being built out of fiberglass screen, eggcrate, Beer bottles(for height), and Aragonite.


thanks for the link Doc!

 

[stringcheese]

Plenum is semi trapped water with near zero oxygen and water flow levels under bed of aragonite that produces denitrafying(nitrate eating) bacterias.
Mine is being built out of fiberglass screen, eggcrate, Beer bottles(for height), and Aragonite.


thanks for the link Doc!

 

[MCsaxmaster]

The plenum likely is not anoxic (no O2) but probably is hypoxic (low O2). What benefit this could provide and why it would provide benefit, even hypothetically, isn't well established, and in fact it appears that it doesn't do much one way or another in terms of impacting water quality.

cj

 

[Big E]

What benefit this could provide and why it would provide benefit, even hypothetically, isn't well established, and in fact it appears that it doesn't do much one way or another in terms of impacting water quality

I think it does in terms of phosphate levels. There are no black sulfate areas like a DSB has. If it's maintained properly it stays clean. I believe the void helps this happen.

When I took my plenum down all that was in the void was white dust from the aragonite that sifted through. There was no dirt whatsoever that could accumulate phosphates.

Without the void the dirt/waste would sit at the bottom of the aquarium traped by the substrate covering it. I believe this is a more viable setup than a DSB in controlling phosphate accumulation.

 

[MCsaxmaster]

There is likely very little sulphate reduction going on in sand beds in aquariums (or on reefs, for that matter). It takes a pretty heavy load of organics to get much suphate reduction.

Why would the plenum affect phosphate? What do you mean when you say "dirt?" What about this dirt would allow it to accumulate phosphate? Why would "dirt/waste" sit at the bottom of a tank without a plenum, but not do that when there is a plenum?

cj

 

[liveforphysics]

I've ran DSB's with no plenum and DSB's with plenums.

DSB's with plenums are absolutely cleaner when torn down. Much less detritus and particles accumulated.

I now use perforated vinal tubing snaking all around the bottom of my tank before I add the crushed coral DSB. The tubing is connected to my closed loop. This keeps a fresh supply of oxygenated water deep deep in the sandbed, which in turn causes the entire DSB to function much like an in tank refugium. The micro and macrofauna population keeps the crushed coral very clean, and nitrates have never been measurable on the salifert low range test. I would never go back to bare bottom or a regular DSB.

Also, in reguards to calcium supply being inhanced with a plenum. If the plenum permits low oxygen biological reactions which result in a sharp drop in pH, this could account for why plenum DSBs always seem to be shrinking. I when i tore down my plenum DSB tank to move, I would guess it had at least 10lbs less sand than when I set it up. It all fit into 2 5gal buckets when I tore it down. When I set it up, I added 2 and a half buckets of crushed coral.

 

[MCsaxmaster]

You are making deep crushed coral beds? That could be...problematic

 

[liveforphysics]

Not problematic when you have moderately strong waterflow continously flowing up from the bottom of them. I could see problems if it were left to just collect low energy waste particles like a dumpster, but pushing tank water up from the bottom seems to completely avoid this problem.

Take a look at PaulB's reef sometime. It's been up with a course substrate medium and reverse flow undergravel filters in excess of 20 years.

I think people trying to use the sand for nitrate processing is where the problems start. I use mine as habitat exclusively.

 

[fishdoc11]

You are refering to a reverse undergravel filter liveforphysics, not a plenum.....and yes PaulB's has worked well for what he is doing but it doesn't perform denitrification.

Curious as to why you would say plenums don't work MCsaxmaster?

 

[Big E]

Why would the plenum affect phosphate? What do you mean when you say "dirt?" What about this dirt would allow it to accumulate phosphate?

It doesn't necessarily affect phosphate, but the setup & maintenance allows you to control phosphate from getting out of control in a negative way. Detritus, food, fish waste ect. will get into a DSB per gravity & continue to sink in over the years. This can lead to phosphate issues.
Some say they can run high enough flow to make all this waste get to their skimmer & other export controls. I don't think that's entirely possible, there will be pockets of accumulation. A plenum is vacumed so you can clean out this waste/dirt periodically so it doesn't build up.

Why would "dirt/waste" sit at the bottom of a tank without a plenum, but not do that when there is a plenum?

Again, the plenum bed is vacumed. DSB's arent' supposed to be disturbed in this manner. When waste gets into the bed it has nowhere to go but down & accumulate. The waste is trapped between the bottom of the tank, the substrate & within the substrate itself.

I believe the void area & courser substrate also help so phosphate doesn't become a problem. When you vacum the bed its easier to pull up that waste. That void creates a false bottom & at least gives you a chance to have a cleaner bed.

A DSB usually has much finer sand grains that trap detritus once it settles in.

I'm not saying all DSB's will fail, just that plenums give you a better chance of long term success & they both funtion the same way in offering nitrate control & sand bed asthestics.

Plenums are simply easier..........you don't need all those worms, bugs, snails, ect. in hopes of turning over the substrate. You do it manually & at the same time directly pull the waste out.

 

[stringcheese]

I read they were anoxic ( not that I know what that means ).

Seems I've developed a stutter.

I agree about the reading of near zero phosphates. I hadn't heard about vaccuuming. I do not plan to ever disturb the plenum.
My design will only yield a small plenum and since it will be in the sump it won't be pretty. I've decided to construct it then wrap the bottom and sides in plastic wrap to lower the amount of aragonite I'll need to seal it from water flow. This way it will be more controlled and less likely to deconstruct itself as well. So far I've cut the eggcrate and screen.
I will layer them in this manner:

ARAGONITE
SCREEN***
EGGCRATE*
ARAGONITE
SCREEN***
EGGCRATE*
BOTTLES**
SCREEN***
EGGCRATE*
BOTTLES**
EGGCRATE*

This should turn out to be fairly tall. The plastic wrap will keep me from having to add 300lbs of aragonite just to cover it.

So, What do ya'll think?

 

[liveforphysics]

I'm curious what you have against waterflow. Giving the plenum waterflow causes it to become a benethic zone, which quickly populates with animals that help improve water quality.

 

[Al]

<a href=showthread.php?s=&postid=10990110#post10990110 target=_blank>Originally posted</a> by stringcheese
I've decided to construct it then wrap the bottom and sides in plastic wrap to lower the amount of aragonite I'll need to seal it from water flow.

I don't get what you mean by using plastic wrap. The plenum system is supposed to work by very slow water flow through the thick layer of gravel over the plenum.

 

[dreamreefer]

that's what i thought, all animals need O2...not sure if it makes sense if someone says the hypoxic zone under a plenum is supposed to cultivate more nitrosonomas or nitorbacter...if there's no flow, hence no air, then it would be dead...maybe the secret is in adjusting to the right level of O2 flowing thru, to get the right colony or be able to sustain one under there...I'm not sure.

Charles Delbeek had a plenum system setup for 5 years, with stats taken frequently. the plenum concept has indeed reduced black toxic sulphate spots compared to DSB's and also, saw a reduction in phosphates quite consistently...this was on an article he wrote on AQUARIUM magazine...

 

[Al]

Stringcheese, you may want to take a look at this link:

http://www.aquariumconnection.com/getLocalNews.php?ArtID=63

This gives practical instructions on setting up a Jaubert (plenum) system.
Personally, I think it looks like too much trouble. The DSB method works perfectly well for me, and since I move every few years, I don't have to worry about the long term effects of a deep sand bed, if there are any.

 

[fishdoc11]

<a href=showthread.php?s=&postid=10991909#post10991909 target=_blank>Originally posted</a> by dreamreefer
that's what i thought, all animals need O2...not sure if it makes sense if someone says the hypoxic zone under a plenum is supposed to cultivate more nitrosonomas or nitorbacter...if there's no flow, hence no air, then it would be dead

Not all organisms need air. Anaerobic means without air. Anaerobic bacteria are what perform denitrification.

 

[dreamreefer]

that's somewhat true, but the anaerobic bacteria turns to nitrates/trites because of the lack of O2 to respire organic matter, not because it didn't need O2, but because there was a lack.

 

[MCsaxmaster]

Curious as to why you would say plenums don't work MCsaxmaster?

What do we mean by "work" in this context? My contention is that, as shown by work by Toonen et al., they probably aren't doing much of anything in terms of affecting water quality.

It doesn't necessarily affect phosphate, but the setup & maintenance allows you to control phosphate from getting out of control in a negative way. Detritus, food, fish waste ect. will get into a DSB per gravity & continue to sink in over the years. This can lead to phosphate issues.

If you're vacuming the sandbed you don't have a traditional plenum system--you have a vacumed sandbed system

I'm curious what you have against waterflow. Giving the plenum waterflow causes it to become a benethic zone, which quickly populates with animals that help improve water quality.

Benthic means 'of or attached to the bottom of a body of water.' I'm not sure what you mean to say here...

that's what i thought, all animals need O2...not sure if it makes sense if someone says the hypoxic zone under a plenum is supposed to cultivate more nitrosonomas or nitorbacter...if there's no flow, hence no air, then it would be dead...maybe the secret is in adjusting to the right level of O2 flowing thru, to get the right colony or be able to sustain one under there...I'm not sure.

No, not all animals need O2. Many sediment-dwelling organisms rely on anaerabic metabolic pathways, and don't use O2. And by this I am not talking about bacteria--many bivalves, worms, and other large, substantial animals rely on anaerboic metabolic pathways in anoxic sediments.

An area becomes hypoxic or anoxic only because O2 demand exceeds supply. If there were no life in a tank--if it were just sterile water and sand--there would be no drop in the O2 below the plenum or in the sand no matter how long it sat there because nothind would be using the O2. Sediments on reefs in nature are usually oxic (high O2) only in the upper few mm or perhaps cm. They normally become hypoxic (due to high demand and limited supply) within a few cm and anoxic below a few cm. In really rich, organic sediments (think mangroves) the sediments normally become anoxic within mm of the surface since there is so much demand for O2.

Charles Delbeek had a plenum system setup for 5 years, with stats taken frequently. the plenum concept has indeed reduced black toxic sulphate spots compared to DSB's and also, saw a reduction in phosphates quite consistently...this was on an article he wrote on AQUARIUM magazine...

Ok, but we have no reason to think that the plenum had anything to do with low phosphate levels in the tank. We could just as easily claim that a particular fish in the tank, or coral, or snail, or whatever helped lead to low phosphates because they happened to be there...

Not all organisms need air. Anaerobic means without air. Anaerobic bacteria are what perform denitrification.

Agreed, see above. Also, just to clarify, while denitrifying bacteria use anaerobic metabolic pathways, not all anaerobic bacteria can cause denitrification. By the same token, all oak trees are plants but many plants are not oak trees.

Chris