Plenums and the wasting "option"

[barryhc]

What many BB'ers fail to realize is that many people like the looks of sand. BB is not a very good option if you want sand. It seems like the BB'ers keep trying to convert people who want sand. I understand that BB is an easier way of keeping the tank clean. But I don't need the easier path.

Right on "Obi-dad"!!!

And for anyone considering putting a drain in the sandbed, you don't need to worry about all the anaerobic discussion if you are only doing an SSB, not a DSB. IMO, a good option to DSB in the dispaly tank is to have a DSB in a fuge (or even a bucket like Anthony Calfo suggests), and is much easier to change out later. This way you don't have to do a balancing act with maintaining anaerobic layers with the drain system.

It shouldn't be that difficult, after installation, because we can choose whatever volume or frequency we like, and change to another schedule as well, at any time.

High Frequency types, like myself, may decide that once a week is adequate, or Low Frequency types, may want to try once a month, for whatever reason.

By the way Obi-dad, "some experts", have stated that Anaerobic activity starts at somewhere between 10 and 20mm deep in a "fine sand bed" ( oolitic-sugarsand ), so, how deep is a SSB?

I can't say that I happen to agree with these experts ( on where this activity begins ), but "many" see the "greater depths" as a "chemical sink" that lasts longer, the deeper it is. I probably do agree with that.

If we "waste" often enough, we may be able to remove some of these compounds, and bacteria that are "working on them ( in the "lower level" ), before the "binding process" is complete. That would be an advantage.

By the way, I expect to have a sand bed in my "fuge" as well. Great idea!

Thanks again > barryhc

 

[voodoody]

Barryhc,
Not really a typo, but I didn't tell the whole story. Nitrification occurs in the presence of oxygen and ammonia is converted by aerobic bacteria (via aerobic respiration) to nitrate and subsequently nitrite. Denitrification occurs in the absence of oxygen (anaerobic bacteria), but in the presence of readily reducible nitrogen sources. A mixture of gaseous nitrogen products is often produced because of the stepwise use of nitrate, nitrite, nitric oxide and nitrous oxide as electron acceptors in anaerobic respiration. So in the two different zones the nitrate / nitrite conversion is proceeding in opposite direction. I hope this make sense.

Voodoody

 

[Obi-dad]

... and ammonia is converted by aerobic bacteria (via aerobic respiration) to nitrate and subsequently nitrite...

Voodoody

Actually aerobic goes first to nitrite, then nitrate.

 

[barryhc]

Barryhc,
Not really a typo, but I didn't tell the whole story. Nitrification occurs in the presence of oxygen and ammonia is converted by aerobic bacteria (via aerobic respiration) to nitrate and subsequently nitrite. Denitrification occurs in the absence of oxygen (anaerobic bacteria), but in the presence of readily reducible nitrogen sources. A mixture of gaseous nitrogen products is often produced because of the stepwise use of nitrate, nitrite, nitric oxide and nitrous oxide as electron acceptors in anaerobic respiration. So in the two different zones the nitrate / nitrite conversion is proceeding in opposite direction. I hope this make sense.

Voodoody

It's to Nitrite, and subsequently Nitrate, in the Presence of . . .

This will "pass" shortly.

The denitrification is making sense. Anoxic, is a term that has been included in bacterial discussions, more often in recent times, and not so much in "earlier" studies and discussions.

Anoxic conditions are supportive of Faculative bacteria( at least ), converting Nitrite to Nitrate, and Anaerobic conditions "seem" to foster denitrification, and lower pH, along with Phosphate binding, hydrogen Sulfide production , and gosh knows what else.

Is this close?

Thanks > barryhc

 

[salty joe]

Voodoody,

I plan on setting up a deep sand bed that will be setting on top of a plenum. The plenum, or void area, will be about 1 inch tall. When the drain valve is opened, the entire plenum will be under negative pressure. Since I will be using Southdown sand, I do not expect water to exactly rush through it. So as I see it, the negative pressure at the corners of the tank will not be very much different from the negative pressure directly above the plenum drain. As far as short-circuiting, or channeling, is concerned, there is no doubt in my mind that that will occur to a certain degree. Since I will be removing a fairly small percentage of the plenum area at any given time, I am not very concerned about it.

The main reason that I want a deep sand bed is so that I can keep creatures like jawfish and certain anenomes. Plus, I like the look of sand.

Another thought on the collection pipe. It is my understanding that the water coming out of the plenum area does not exactly smell like a fresh sea breeze. A vented PVC cap could easily be constructed and filled with carbon.

If we keep this thread alive long term, there is no doubt in my mind that we can achieve a deep sand bed that will last indefinitely. I'm sure a lot of people think that this is a nutty idea, but this is the only way progress in this field or any other field for that matter is made.

 

[barryhc]

Interesting rehash of an old thread. About a year ago on contacted Hawke privately and got a response. He eventually stopped using his plenum system and went bare bottom. He said he reached a very simple conclusion. A plenum system could be made to work, but why treat waste in the tank, and be at risk of a biological over load and upset, when it is easier to design a system to remove the waste to start, and eliminate the major biological load that it causes.

I think he asked me something like....would you build a compost toilet in your house when it is cheaper and easier to flush a standard toilet. ?

So, why not design a system to remove the waste to start, and eliminate the major biological load that it causes . . . .

Then, go ahead and put in your plenum, and whatever substrate that you have decided on for whatever reason, and do as you please with your reef and your inhabitants.

Just a thought. That's what I'm doing. > barryhc

 

[barryhc]

RIGHT ON, SaltyJoe!!!!!!!!!

Just wathch out about that "membrane" idea. "plug", "plug" "plug"

We are getting somewhere, Joe, and you are helping a lot!

Thanks, > barryhc

 

[voodoody]

Obi-dad

Actually aerobic goes first to nitrite, then nitrate.

Yes, you are right. I did make a typo that time.

voodoody

 

[barryhc]

The main reason that I want a deep sand bed is so that I can keep creatures like jawfish and certain anenomes. Plus, I like the look of sand.

Exactamundo!! especially the Jawfish!

Another thought on the collection pipe. It is my understanding that the water coming out of the plenum area does not exactly smell like a fresh sea breeze. A vented PVC cap could easily be constructed and filled with carbon.

This is progress, absolutely!! I love it!

Thanks Joe, keep these good ideas coming. > barryhc

 

[voodoody]

Salty joe,
What is your plenum? How is your void area constructed?
voodoody

 

[salty joe]

This is all in the planning stages. My plenum will just be pieces of PVC supporting egg crate. I will put a piece of screen on top of the egg crate. If Barry can convince me (hint hint) that a layer of coarser sand will prevent the Southdown from entering the plenum area, that's the route I'll go. Anyway, from there it will just be a regular old deep sand bed constructed with Southdown sand. Probably about five or 6 inches deep.

 

[barryhc]

This is all in the planning stages. My plenum will just be pieces of PVC supporting egg crate. I will put a piece of screen on top of the egg crate. If Barry can convince me (hint hint) that a layer of coarser sand will prevent the Southdown from entering the plenum area, that's the route I'll go. Anyway, from there it will just be a regular old deep sand bed constructed with Southdown sand. Probably about five or 6 inches deep.

Joe, the system that you are preferring, is just as likely at this point, to be a good system, as any of the others. We just don't have any better information yet. Of course, "we" will be developing it.

I will have "drivers" from HP by Oct. 4th. I have done a screen capture from "CAD", but it is 213 kb, and RC is not allowing that file size yet. ( I'm working on "them" )

In the mean time, take anything, that is vaguely 4" dia. ( or 2" dia. if need be ). Draw 3 circles that touch each other, and then draw a circle that fits into the remaining space between the three circlres.

That is all you will see when I can post the image anyway. Merasure the little circle, it will be 16% of the size, of the larger circles. Then think about it.

I hope this helps, and I love the charcoal, lets put a little "draw volume adjustment tube", right down the center of the carbon "destinker".

Thanks so much! > barryhc

 

[barryhc]

I have started a new thread called "Bacteria-Anoxic-Anaerobic?" in the "Advanced Topics" forum.

We can certianly continue to discuss bacteria here, but some of the material that I am finding and posting in the new thread is interesting, no doubt, but also, in some cases "rather heavy".

So just to keep this thread a lot "cleaner", I'll be looking in the new thread for "clarified" and up to date "bacterial process" information.

Thanks all, > barryhc

 

[voodoody]

Salty joe,
I am not a sewage waste expert. Idrhawke apparantly was. According to him, your planned construction will not work well as the lack of a reasonable number of discrete holes in the plenum will lead to large scale "short circuiting". According to him you will be detoxing only a very small percentage of your sand bed. Again, I am not an expert, but his original thread was quite convincing. I am convinced that his design (or a modification of it - such as the grid that I constructed) can work. The main issue is how much to drain and how often. I think that infrequent drainage is key to maintanence of the appropriate bacterial flora. I agree that this is difficult to prove.

 

[Obi-dad]

I need to explain about my posts - my sand bed drain system does not involve a plenum, and is not a DSB, just an SSB, so my system doesn't really fit in with the title of this thread.

 

[barryhc]

I need to explain about my posts - my sand bed drain system does not involve a plenum, and is not a DSB, just an SSB, so my system doesn't really fit in with the title of this thread.

Just the same, Obi-dad, we are all interested in the bacterialogocal and chemical processes that occur in our tanks and in our substrates.

If you are draining, flushing, or wasting some water, and what's in it, from your substrate, you are "plenty close enough".

And for anyone considering putting a drain in the sandbed, you don't need to worry about all the anaerobic discussion if you are only doing an SSB, not a DSB.]

By the way, an SSB works much the same as a DSB, in most cases, unless the depth gets "pretty short", like less than 1 1/2".
The shallower "bed" just has a smaller "chemical sink", which fills up faster.

If the "bed" is so shallow, as to not have this "chemical sink", then why would you bother to "drain anything from it?

Just a thought. > barryhc

 

["Umm fish?"]

Hey! I got this off of the sulphur beads thread. Roadtoad says:

There was an article in Science a couple of months ago that dealt with the different environments in marnie sediments and the energy-producing chemistries that the resident bacteria utilized.

Did anyone see this article?

 

[voodoody]

Obi-dad,
Okay, I can see that. Shallow sand bed = less potential for short circuiting. Still get the better look of sand (compared to bare bottom). Remember though, since detritus removal will be harder than BB, you may need more live rock for denitrification than a BB or DSB system (unless you vacuum the sandbed very frequently).

 

[Obi-dad]

I have a DSB in the fuge, so my nitrates are zero. I am hoping this approach is the best of both worlds - the look of sand, no nitrates, and no (or at least not a much) 'sewage trap'.

 

[barryhc]

If Barry can convince me (hint hint) that a layer of coarser sand will prevent the Southdown from entering the plenum area, that's the route I'll go.

Testing 1 - 2 - 3 - . . . .

http://reefcentral.com/gallery/data/4097/957994mm_Particle_Migration_45-100.jpg


So, this is just geometry. It seems simple enough to me.

The "gravel" should be "regraded" ( requalified ) by the user, using a screen with the same opening as the minimum size grade required, in order to remove the miscellaneous "dust and grit" from the intended substrate.

The gravel can then be used over a screen with openings at 75% of the size used for "grading".

Now you have a "gravel membrane". :idea:

> barryhc