Plenums and the wasting "option"

["Umm fish?"]

Right, barryhc, but I'm refering to a planar mental block. I don't think our sandbeds have these perfect little layers, but that's the way people think about them. And I think that the mental block and people's reluctance to let go of it is harming a lot of the recent discussion.

Well, I both agree, and disagree. Let me explain. You are quite right in my opinion, about the planar concept. It is there in some places, and not in others. Where it is planar, that just means fairly even, in terms of depth, but much of this is a "contiuous gradient" and "in flux", especially during the "wasting" which I am counting on. And it isn't necessarily even everywhere, but I don't think it has to be. The bacteria are very adaptive.

No, I don't think your efforts to avoid channeling will be detrimental.

The only real problem I can think of with this is only really a problem for frequent wasting ( ). Thought problem: We are relying on diffusion to send all the nasties down to our manifolds. But what are these nasties displacing? By constantly sucking a bunch of O2 rich water down channels to the tank bottom, will we see a diffusion of O2 rich water back up through the sandbed? I think this is kind of Doug's point (or at least one of them ): will this process lead to a completely aerobic bed?

But, I know that you are planning to remove minute quantities of water with each draw and I assume the O2 will be used up relatively rapidly from bacteria around the channels in the sandbed and along the plenum, so I don't think it's a horrible problem as long as you don't over-waste.

I wish we could see what's going on down there. What if you wound up with a top and bottom aerobic layer (here's me coming in with a planar concept, per above discussion ) sandwiching an anaerobic and anoxic zone? What the heck would that do?

 

[barryhc]

I think that's the mental block and people's reluctance to let go of it that is harming a lot of the recent discussion.

No, I don't think your efforts to avoid channeling will be detrimental.

Thanks, I needed that, I was about to have a crying spell!! :lol: :lol:

The only real problem I can think of with this is only really a problem for frequent wasting ( ). Thought problem: We are relying on diffusion to send all the nasties down to our manifolds. But what are these nasties displacing? By constantly sucking a bunch of O2 rich water down channels to the tank bottom, will we see a diffusion of O2 rich water back up through the sandbed? I think this is kind of Doug's point (or at least one of them ): will this process lead to a completely aerobic bed?

Absolutely not, I will test for it ( oxygen ) with some type of probe or "water collector" as I have described previously, to determine, and modify oxygen levels so that this condition that you are concerned with does not occur. I am concerned with this as well, and I WILL NOT LET IT OCCUR!!!!!!!!!!!!!!!!!!

But, I know that you are planning to remove minute quantities of water with each draw and I assume the O2 will be used up relatively rapidly from bacteria around the channels in the sandbed and along the plenum, so I don't think it's a horrible problem as long as you don't over-waste.

I at least, certianly will not "over-waste". Only that amount that is conducive to controlling the oxygen gradient to a depth that is considered to be beneficial to "stretching" the "non-anaerobic" populations will be utilized, and the Anaerobic population will become "somewhat thinner", not non-existant.

I still plan to target the beginning of the anaerobic zone at somewhere near the beginning of the oolitic layer of sand, and could most certianly turn out that is not the best place for it, or the best depth of oolitic sand, but is still my best guess, and until some better method is identified, I still currently plan on using this model.

If this model has a flaw, or more importantly, a betterment, that I or anyone else can identify, I will adjust my thinking to be sure.

Remember, that at the 7/64" depth of "column water" for each draw, that I am still currently proposing, the draw depth within the substrate will be about 7/8", and it is the recovery rate of the bacteria, or the time it takes them to consume the oxygen in this 7/8" deep layer that has recieved oxygen, at whatever depth that this happens to be, that wiil cause a necessary modification to the wasting "schedule".

The bottom layers of coarser gravel, along with the tight packing of the feeder tubes, as I have shown in the 55 gal. graphics in my gallery, will cause these vortex shapes to overlap, long before they get to the bottom of the oolitic layer of sand, and most of the oolitic layer should also remain relatively undisturbed, so most of any channeling is going to occur above the oolitic layer, and the oolitic layer itself helps to even this out before any flow gets to the bottom of it.

Please note that I have the feeder holes, only in the bottom of the feeder tubes, and pointing therefore at the glass, which is going to eliminate nearly all funnel shaped activity of the water flow in the plenum area.

Now, if you actually prefer these funnel shaped oxygen gradations in your substrate, they are easy to promote, as you have pointed out, you just have to decide how you will control them if at all, and that MIGHT BE a little more complex. ( If I meant "would be", I would have said WOULD BE, but I don't usually play those kind of games )

I have actually done some thinking along these lines, and I think the concept could have some merit, but it would certianly be a lot more difficult to test for, and so I have avoided even discussing it thus far.

Above the oolitic layer is the somewhat coarser layers 1 and 2, which should remain primarily aerobic anyway, which is one of the things that I have to test for to modify the wasting volume and frequency schedule. Without this testing and schedule modification all kinds of "who knows what" might occur.

I wish we could see what's going on down there. What if you wound up with a top and bottom aerobic layer (here's me coming in with a planar concept, per above discussion ) sandwiching an anaerobic and anoxic zone? What the heck would that do?

I will check to see what is going on down there, by way of water testing at many depths in the substrate, at least one per inch of depth.

Check the Biological Phosphate Removal thread that I have referred to, there is some terribly interesting concepts going on in waste management, that have to do with modifying the oxygen level back and forth in a substrate, in order to force both denitrification and puosphorous removal to occur biologicaly, and at a much higher rate, for both the phosphorous and the nitrate.

Many of these systems have been up and running for many years, and are accepted methodology. Fresh water is not the same as saltwater, but it isn't that far off either.

There is a new version, just out, that uses a single stage, and only changes back and forth between Aerobic and Anaerobic conditions, over periods of less than several hours, which is exactly what will happen with frequent wasting.

Thanks again Andy, > barryhc :beachbum:

 

[salty joe]

Posted by Barry

I have proposed 6mm oprnings in this screen, at midway in a 3" depth of "oolitic", or maybe slightly coarser sand. That is a .240" opening, which will certianly stop fish and large substrate disturbing animals from going further, but which will allow nearly all other types of "fauna" to pass through, and do whatever "work" they are good at deeper into the bed.

I think that this is an outstanding foundation for a sand bed of this type. Also, the idea of using progressively larger gravel and sand to block fine sand from the plenum is very ingenious. Before I started reading this thread, I was beating myself up trying to find some kind of membrane to do just that.

When I set up a plenum, and I can always change my mind, but at this point I am leaning toward a void space with a sand bed suspended above, without PVC. With this type of set up, I think perhaps a slow draw would be beneficial in that it would minimize channeling.

This is exciting because it's new and I honestly believe that we are onto something. This is a great thread and I thoroughly enjoy it.

A snowflake eel, huh? Very cool fish. I had one for 11 years and I might still have it today excepted it jumped out. And I thought I had my tank very well covered. He slipped out of a hole I had made for the heater wire. I noticed as he grew larger he became a lot less shy. And when he was hungry he got real rowdy. He was hungry when he jumped.

Joe

 

[barryhc]

A snowflake eel, huh? Very cool fish. I had one for 11 years and I might still have it today excepted it jumped out. And I thought I had my tank very well covered. He slipped out of a hole I had made for the heater wire. I noticed as he grew larger he became a lot less shy. And when he was hungry he got real rowdy. He was hungry when he jumped.

Yeah, he's a bit bigger around than a pencil and about 8" long. When he finds a chunk of frozen Krill ( about 1" length of pencil dia. ), he has to "KILL IT", and I mean REALLY KILL IT TO DEATH!!!!!

The thing is, I have no cover at all on the tank, on top of which, he is always finding his food right at the surface. I might have to go back to feeding the open brain coral, and let him steal it from him, until I get the "lid" built.

Geeze, the complexity will never cease!

I'd better get on to a temporary lid, see ya. > barryhc

 

["Umm fish?"]

Please note that I have the feeder holes, only in the bottom of the feeder tubes, and pointing therefore at the glass, which is going to eliminate nearly all funnel shaped activity of the water flow in the plenum area.

But, if detrius or mulm or whatever does build up down there, having the holes on the bottom makes it much more likely they will clog. I'm currently searching for a magnet with a very low profile that'll slip under the pvc pipes (the fittings keep them just off the glass) so I can stir things up.

 

[salty joe]

Posted by Barry

Now Jaw fish are probably the worst in this respect, and they are one of my favorites as well. I have previously posted many times, that I believe a seperate area, designed to accomodate the needs of this animal, might be set-up during initial aquascaping, to help with the cave building of this animal, and Tom at Inland Aquatics has some good information on how to go about this.

Something that I have considered but haven't done yet is take some screen mesh and make a large tube about 12 inches in diameter and taller than the tank is deep. Decide where I would like my jawfish to live and sink one end of this mesh tube way deep into the substrate. Mix a lot of gravel and rubble into the substrate inside this mesh tube. Then I would simply turn the jawfish loose inside the mesh tube and put a dinner plate or something on top to keep them from jumping out. Is this anything like what Tom from Inland Aquatics suggests? I suppose you could try to separate the jawfish area from the plenum area, but the way those guys dig that seems pretty iffy.

 

[barryhc]

But, if detrius or mulm or whatever does build up down there, having the holes on the bottom makes it much more likely they will clog. I'm currently searching for a magnet with a very low profile that'll slip under the pvc pipes (the fittings keep them just off the glass) so I can stir things up.

I don't expect much mulm etc. when wasting everyday, but back- flushing can be done, then there was that recent idea of circulating plenum water through a canister filter.

Are you wet yet? I saw your pictures, and the final manifold looks pretty good. Lot's of plumbing, heh?

By the way, I have been thinking a little more on the channeling issue, and the eggcrate, and it's effect on channeling. I think the current model is still excellent, as I have described recently, but there is some merit in eliminating the void space as well. If the gravel membrane is used, and a final layer of coarse gravel is layed directly on the plumbing, without eggcrate or screen, It will tend to localize the draw, which would be particularly good if someone had a jawfish, and was going to omit the critter screen and allow him to dig all the way to the plenum.

I may even set up a portoin of my tank this way just for the jawfish, or the whole tank, and just no critter screen in the "jawfish playground".

I can't wait to "see you get wet". What kind of animals do you intend to keep?

> barryhc

 

[barryhc]

Hey Joe, you got your post up while I was typing. Interesting that we're both on the jawfish thing by coincedence. I have to admit it was the jawfish and gobies that got me started on this thing a year ago.

Something that I have considered but haven't done yet is take some screen mesh and make a large tube about 12 inches in diameter and taller than the tank is deep. Decide where I would like my jawfish to live and sink one end of this mesh tube way deep into the substrate. Mix a lot of gravel and rubble into the substrate inside this mesh tube. Then I would simply turn the jawfish loose inside the mesh tube and put a dinner plate or something on top to keep them from jumping out. Is this anything like what Tom from Inland Aquatics suggests? I suppose you could try to separate the jawfish area from the plenum area, but the way those guys dig that seems pretty iffy.

Actually it is a matter of putting the gravel and rubble where you want him to make his home. According to Tom, the jawfish prefers not to travel that far while building his den, so you put some larger gravel and rubble right in the substrate when you set-up the tank, and sprinkle some right over the intended digging area. Apparently the Jaw fish is pretty smart, and recognizes that good building materials on the surface, are a good indicator of more good materials underneath the surface.

Then keep a pile of rubble, larger gravel, shells, etc. immediately next to where you want him to dig. If you have PVC plumbing, you can use the idea I just posted above, with no eggcrate etc., although I think I might screen him away from the bottom by at least 1" above the plumbing with the 6mm mesh.

I am quite determined to keep a jawfish, and co-exist peacefully, without an unduly compromised sandbed. The modular plenum sections in the 55 gal. graphics in my gallery allow a single section of the plumbing to be under an area with different substrate conditions and still not significantly effect the remainder of the plenum and substrate.

I have a whole lot more consideration into the design than I have been able to explain about so far ( especially recently ), and this consideration for different treatments in different areas of the tank is one of them, and was one of the reasons for the seperate plenum sections.

Thanks, > barryhc

 

["Umm fish?"]

Well, oddly enough, it's always been my intention to place 3-4 jawfish in as the first fish (when I'm ready for fish). There is a jawfish exhibit at the aquarium near me and my daughter and I have always spent lots of time watching them steal building materials from each other. This may be the only time in the recent history of saltwater tanks in homes with children that some other fish goes in first, even before Nemo. It's very exciting....

 

[barryhc]

There is a jawfish exhibit at the aquarium near me and my daughter and I have always spent lots of time watching them steal building materials from each other. This may be the only time in the recent history of saltwater tanks in homes with children that some other fish goes in first, even before Nemo. It's very exciting....

Andy, could you give us some more information on jawfish in general, either here or by PM, your thread, or whatever else.

You will be up and running before Joe and I, and you might even learn things that can't be read up on, just by observing at that local exhibit. More than likely!!

It is really hard to say "favorite" with only one space on the list, but Pearly jaw fish would have to be really really high up for me.

Early introduction is probably a very good idea.

Funny thing BTW, I had couple of Pearly jaw fish in my first salt water tank, about 30 years ago, and they dug their burrows into 4mm dolomite without any difficulty at all. They met their demise early however at about 9 mos. from other factors, and didn't get replaced.

I didn't know squat at the time. Neither did the LFS, or hardly anyone else. They were only about 2" long though, and a burrow for a mature jaw fish probably couldn't hold up well made from that grain size.


Thanks again, > barryhc

 

[barryhc]

Also, I didn't know about your desire for Jawfish, but now having heard of your plan there, and having seen your plenum pictures, you might want to think about the most recent postings regarding the "Jawfish playground".

Something like putting in a piece of plexiglas between plenum sections, and or a critter screen 1" above the plenum, or "this", or "that", whatever. I guess I'm just thinking out loud, but jawfish get me so excited, I just can't help it.

In any case, tell us please, what if anything you do to help accomodate them.

Atta-boy Andy!!!!! > barryhc

 

[salty joe]

I tried to get jawfish to live in a certain spot by putting rubble into it and on top of the substrate. It took them over a month to finally find and dig into the rubble spot. Meanwhile, they were digging under rocks and causing them to tip over. Their tunnels kept collapsing because they were digging into fine sand. One of them died in the process. I ended up aqua scaping all over again. This time I placed all the rocks on PVC " legs" so that even if the jawfish dug all way to the glass, the rocks would stay put. Once they settled in, they turned out to be lovers. The male would slip into the females tunnel and disappear with her for a while, and sometimes the female would come and visit the male. Every couple weeks or so the male would brood a huge load of eggs in his mouth. Jawfish are too cool for words!

Course gravel on top of a PVC matrix makes a lot more sense to me than putting the PVC matrix in a void. If I were going to go this route I think I would put a piece of screen on top of the course gravel. I think that would minimize channeling the best. I think I just changed my mind again and now I like the idea of the PVC matrix with gravel on top better than an empty void space. The PVC matrix with gravel on top should function pretty much like a footer drain in a house.

 

[barryhc]

Jawfish are too cool for words!

Course gravel on top of a PVC matrix makes a lot more sense to me than putting the PVC matrix in a void. If I were going to go this route I think I would put a piece of screen on top of the course gravel. I think that would minimize channeling the best. I think I just changed my mind again and now I like the idea of the PVC matrix with gravel on top better than an empty void space. The PVC matrix with gravel on top should function pretty much like a footer drain in a house.

Thanks a heap Joe, I'm sure you've noticed that I have been "migrating" already towards possibly eliminating the void space myself, even without knowing how nasty they can be.

I really think that the "gravel membrane", and the critter screen is our best bet, although, just now as I'm writing this, it occurs to me that If most of the critter screen was kept at about 2 1/2" to 3" deep, they would not be able to foul up the oolitic sand, that I am currently wanting to use, and they would give up sooner, and find and then use the area that has been prepared for them.

This would obviously limit some of the rock toppling as well.

Thanks again > barryhc :beachbum:

 

[barryhc]

Another question for you Joe, I am wondering about them toppling the rocks. Would you say that the Jaw fish has a propensity to put his "burrow" very near, or "under" rock formations. If so, I want to make the area where I try to promote his digging and dwelling, as near to what he "usually" likes as possible.

Then I can create this environment while setting up the substrate and initial aquascaping, so he can get to this "ideal" place sooner, for the betterment of the rest of the tank. And now I can put his critter screen closer to the plenum, and maybe even seperate this section from the remainder of the tank, as I suggested to "fish".

How far apart were the male and female burrows, by the way?

> barryhc

 

[salty joe]

Their burrows were probably about six or 8 inches apart. I don't know if they are still there or not, but in the photography forum I posted some pictures of my male jawfish with this mouthful of eggs. This was probably a couple years ago or so. The picture was titled jawdaddy. Or jaw daddy.

As I understand it, when jawfish dig under rocks and so forth, it is because they are still freaked out. Normally, they dig a burrow in an open area of substrate.

Whether I have jawfish or not I know that I will never set up a reef tank again without supporting the rock all the way to the bottom of the aquarium. I lost a really nice brain coral and some other critters got pretty beat up when the rocks came tumbling down.


The jawfish that I had were Tiger jawfish. I doubt if they are any smarter or dumber than a pearly jawfish. It caused me a great deal of grief to watch these guys digging under rocks all over the place, stressing themselves out, having one disappear on me, wreaking havoc in my aquarium, when they had a perfectly suitable place to dig in. Which they finally did, and then it was pure sweetness. If you guys are going to get jawfish, please consider the mesh tube.

 

[barryhc]

I think I just changed my mind again and now I like the idea of the PVC matrix with gravel on top better than an empty void space. The PVC matrix with gravel on top should function pretty much like a footer drain in a house.

Well, quite so, although I still highly prefer to collect towards the center for flow balancing, Gosh I'm a "fanatic" aren't I?

This is the reason for all the seperate "modular sections" of plenum "matrix".

Some people who aren't into burrowing critters, may want to stay with the plenum space, and somewhat simpler plenum plumbing, but it seems like we are "zeroing-in" here somewhat on a system that allows "zones", or habitats to be placed at various locations in the tank, with varations in substrate, if need be, and still draw the waste water from a single drain tube, and volume or frequency control mechanism, without much difficulty.

Also, by eliminating the eggcrate and screen at the eggcrate, It becomes very much easier to do somewhat more elaborate plumbing. I have a design both for the 120 gal. ( 4' x 2' ) that "Fish" has as well as for a 180 or 220 gal. ( 6' x 2' ) like I am going to put in soon.

This makes it a lot easier to get the elaborate plumbing in, and NOT have it "stick-up", to get the "draw-point "centralized" as shown in the "55 gal. plenum option" graphics. Now, all the plumbing, including the "stepping-up" for total flow requirements, can be kept on the bottom of the tank without concern for eggcrate etc.

This would be a big help for "fish" who wants to strap down his rock work to the plenum tubes.

Actually, if you look at the last 55 gal. plenum design in the gallery, you should note that there are (4) sections for a 4' x1' tank. The sections are intended to be modular and cover one square foot each.

So you can set up any multiples of one square foot, as a "habitat" for a certian type of animals within a single tank. At least as far as the substrate goes, and that is usually the tough one. Multipes of one foot, are common for a large variety of tanks, as you get bigger, and therefore have enough space to seperate habitats in.

Any thoughts? > barryhc

 

[barryhc]

Testing, testing.



Just checking to see if this thumbnail thing works.

here goes!

I guess not, I'll have to keep working on that, they won't let me delete this post, oh-well.

> barryhc

 

["Umm fish?"]

Man, do you guys ever work?

Okay, as far as the jawfish thing goes, here is what I know. Actually, since this is all off the top of my head, it's pretty likely that there'll be some errors. First off, there are a bunch of species, most of which are pretty unstudied scientifically. They range in size from your pretty normal 3-4" guys up to some pretty big monsters. I believe that the entire range of species are mouthbrooders, and there are some particularly amzing pictures of them with stuffed mouths in the Basslets, Dottybacks and Hawkfishes book (which is not in front of me, unfortunately).

Some of the species are more solitary. Those tend to be pretty nasty to conspecifics. Others hang in colonies. Those tend to be the ones you want (in my opinion) if you want to see some of the fun interactions. I believe that the yellow-headed fall into this latter category, and, in fact, I believe I remember that they are very attached to their groups. Once they build a burrow in a colony, they tend not to leave their entire lives. Bummer if you get a bad neighbor.

Some of the jawfish species feed on sand-dwellers. Some feed on plankton in the water-column right above their burrows. The latter are the species that are most likely to be out and putting on shows for you and guests. The yellow-headed are plankton-feeders and supposedly spend about 80% of their awake-time feeding (which means that you'll see them out quite a bit).

It's important to get your fish in the morning (for whatever light-cycle you use). They will spend the day frantically building burrows. Supposedly, if they can get a burrow dug that first day, they will be much less likely to jump out of the tank that night. They are jumpers, at any rate, so a strong cover is necessary.

The yellow-heads at the aquarium were fascinating and hilarious. I guess they spend whatever time they aren't feeding working on their tunnels. They dart in, they dart out, they spit a rock. While one is in it's burrow, another sneaks over and steals some choice rock. The first one comes out, spits a rock, then looks all over the place for the stolen rock. And on and on.... Supposedly, you should keep bits of shell in with them, too, because they will pull a shell over the hole in the burrow for the night.

They are pretty possessive over their tunnel. I've heard that yellow-heads can be nasty to other small fish. They hide from bigger fish, but if the bigger fish come too close to their burrows, the yellow-heads spit rocks at them.

Pretty cool at any rate!

 

["Umm fish?"]

Oh, something I forgot to say. Jaws like to find and burrow under large flat rocks. They make good roofs for their caves.

 

[sradmin]

Thought I'd liven it up again with a couple of pictures: It's Gobbles, the pearly jawfish. I know, I know... my girlfriend named him. He shares his reef with one other tankmate, a Royal Gramma.

I've read that, given a preference, jawfish prefer a deep substrate (6" minimum) and will dig burrows out in the open. (The jawfish I've seen while scuba diving have been this way, congregating in large groups with burrows each a foot or two apart). Under less than "ideal" circumstances, they will make a burrow under a rock. Whether or not a burrow proper equates to a "happy" jawfish, I cannot say- Gobbles lives in about 3-4 inches of 1-3 mm sand, and he burrows under a rock, but he seems quite adaptable and perfectly fine with less than 6 inches of sand. In fact, he is a very bold fish, spending most of his free time vertically in the water column above the entrance to his burrow. The rest of his time is spent on home maintenance and eating. Definitely one of the coolest fish I've kept. I love their expressions!