A Sediment substrate that works

[mojoreef]

Ok on the mesh what micron size do you figure. I have found some nylon as you were refering to mike, and it comes in a number of sizes all based on microns. So when we are talking about things that should be able to pass through the plenum, what is it exactly that we want to go through. Are we talking about just water, liquids, solids stuff like that. I think once we come to a determination on that then we can match up the micron size nylon or screening to accomidate.

Mike

 

[MikeS]

I would think you would want mostly just water passing, let the solids break down in the substrate.

Not sure on the micron size of the fabric...I'll go see if I can find a piece that has that rating on it...

Mike

 

[mojoreef]

Ok maybe I am going backwards here. I think we should spend a little time on the media first, then we can do the mesh to fit in with it, kind of opposite of what I just said lol. Are we going with two different types of media. Coarse grain on top then fine grain below, or just one or the other. Personally I am leaning towards the use of two types of media, seperated by different mesh types.


Mike

 

[Witfull]

here is a thought,,the bottom layer say an inch at the most thick of a crushed coral or agronite to allow the dirt to fall through the substraight and to the plenum...above that 3 inches of fine sand to be the DSB. between them a screen that is fine enough to stop the 2 medias from mixing, except for the DSB that melts through the screen and that will eventually work its way to the plenum and be pulled out.

 

[NaH2O]

I have a concern about sand substrate being used inbetween an upper layer of substrate and the plenum. As the lower pH melts the sand, then what would happen to this layer over time? Would it be a maintenance issue....and have to be built up in time? Or am I thinking too much about it.....

I almost think one type of substrate would be better than two. What benefit would there be by having 2 types of substrate?

 

[MikeS]

yeah, sand melting could be a problem.... or also sand "cementing" could be a problem...uniform diffusion into the plenum is pretty important IMO to the proper fuctioning of the system. Not sure on that issue...good point.

On the screen...I'm concerned that it will clog with fines and crud...that's why I'm in favor of a fabric, even with a lot of sand fines and gunk on it, it should still remain permiable to water.

Mike

 

[Maxx]

I'm concerned that it will clog with fines and crud...that's why I'm in favor of a fabric, even with a lot of sand fines and gunk on it, it should still remain permiable to water.

But we need to remove the gunk that would clog it up in order to make this work. So its ability to work w/ stuff clogging it up might wind up as a liability rather than a helpful issue.....
Or did I somehow miss something important?
Nick

 

[Witfull]

that was my thinking with a larger CC underneath to allow fallthrough. once it got small enough to go through the screen it would work its way down or just be pulled down with the draining.

 

[RedEyeReef]

My vote is one lay of sand for pure ease... I personally am not going to mess with different layers of sand seprated by screen, but that is just me.

What about something like Florida Marine Grade sand? It is a good mix of size sand. KISS (keep it simple...)

My hope with this is that the gunk can settle in the plemun and be sucked out... if this is the goal, I don't see Sugar Size sand working real well or a real small micron mesh either. So is our goal here to get the gunk out or the water?

 

[Maxx]

My hope with this is that the gunk can settle in the plemun and be sucked out... if this is the goal, I don't see Sugar Size sand working real well or a real small micron mesh either. So is our goal here to get the gunk out or the water?

Exactly what I was wondering...cause w/o removal of detritus, we're basically just doing a water change from the bottom of the tank.....
Nick

 

[NaH2O]

I see what you are saying, although I think it would be more than just a water change. We would be removing end products of anaerobic processes, not just particulate.

 

[MikeS]

I see it like NaH20 stated...removal of byproducts and end products...

MikeS

 

[mojoreef]

Great stuff, some really good points are being brought up. Melting and hardening being a couple of really strong ones. I think taht for these reasons alone sandwiching different grade would not be a viable option. The particulate that would be building up on the bottom would be very fine, say like dust size particules. Using a realy fine sand would make diffision challenging to say the least, so lets talk some more with the reasoning behind it.

Mike

 

[NaH2O]

I don't like the idea of having a fine particle sand being used. To me - I think there would be too much involved in getting it to function properly - like detrivore kits....in order to get the detritus broken down and moved through the sand bed. Although, I suppose if the sand was shallow enough? Another question I have is if the substrate was crushed coral, would phosphates be an issue?

 

[Maxx]

We would be removing end products of anaerobic processes, not just particulate.

I see it like NaH20 stated...removal of byproducts and end products...

mikeS....
I'm concerned about removal of detritus/particulates which will decompose and thus give off more by products and end products. To me it makes more sense to remove the source, instead of only removing the product.
I think that by using a coarse gravel/substrate, we are able to do that easier than w/ a fine sand. This is because you're going to have detritus and bacterial flock, (which will contain all sorts of nasties that the bacteria have eaten and discarded etc) collecting in the sandbed, and not allowing them to be removed by this smokin' cool new plenum system we've just dreamed up. Now you're gonna have to do the same maintenance on it that would be needed on a DSB. And if you're gonna do that, why go thru all the bother/hassle etc of making/buying it, when you can just have a DSB?
Not trying to be argumentative, just explain what I see to be a potential problem....
Nick

 

[mojoreef]

Yea this is going to be the interesting part of the equation. If we go fine we are just going after byproducts and unprocessed (non nitrogen based). i think the unit will still accomplish beating the eventual build up and will also keep the top layer anaerobic. If we increase the particle size we would have better of both of the above but we would get an added bit by processing raw detritus, this could help increase the bioload handling capability of the system as a whole. Lets put some thought into it.

Mike

 

[MikeS]

mikeS....
I'm concerned about removal of detritus/particulates which will decompose and thus give off more by products and end products. To me it makes more sense to remove the source, instead of only removing the product

Point well taken...

Two things...I'm still looking at this from a pro-DSB standpoint. IMO if the byproducts and endproducts can be removed, or at least substantially reduced, than this system is a great improvment over my existing DSB. Even if the system isn't perfect and said byproducts still accumulate slowly in the substrate, if this system can significantly extend the effective life of the substrate over the DSB then it is a winner from my perspective.

The other thought I have (forgive me if this does not make sense, sometimes I have a hard time putting my thoughts into words) is mechanical difficulties associated with solid waste removal. IE clogging of the system. Of course removal of the solids would probably be more ideal, but I feel that keeping the solids above the plenum and letting the substrate break them down and then removing the end/byproducts would be more practical. And you will also get the benefit of a more enhanced bioload capacity in the tank. This is something of a compromise, trading the quick removal of the solids for a design that will be less prone to clogging, solid waste buildup in the plenum itself, ect.

I think that by using a coarse gravel/substrate, we are able to do that easier than w/ a fine sand. This is because you're going to have detritus and bacterial flock, (which will contain all sorts of nasties that the bacteria have eaten and discarded etc) collecting in the sandbed, and not allowing them to be removed by this smokin' cool new plenum system we've just dreamed up. Now you're gonna have to do the same maintenance on it that would be needed on a DSB. And if you're gonna do that, why go thru all the bother/hassle etc of making/buying it, when you can just have a DSB?

A single layer of a more coarse substrate may be the way to go, it would certainly be less complicated, and less prone to melting or cementing. My main concern with that is disruption of the anerobic zone by perhaps too rapid diffusion of O2 rich water into the substrate. (I know I know...still looking at that from a "sand junkie" viewpoint... ) But I'd go with a single coarse substrate if I thought I'd still get decent nitrate reduction out of it.

The point on the maintenace issues of this vs a DSB are well taken too, the exact same thought runs through my head. However, I think that if this system can at the very least control the end/byproducts and extend the substrate life with no more maintenance than a DSB, it's worthwhile.

Not trying to be argumentative, just explain what I see to be a potential problem....
Nick

you are not arguementative at all....I want to see all the potential sides to this before I go out and slap one in my tank!

mojo....you are so much better at putting what I'm thinking into words than I am...:lol: You summed it up well...

MikeS

 

[mojoreef]

I am tending to lean towards the thinking of Mike on this one. One thing to really think about here Nick is that with large particles the ease of diffusion in is going to be close to the to the ease of leeching out, so thier is a slipery slope here we have to be aware of. In studies done by A Thiel and C Delbeek they should a big drop in orp over time as the plenum system aged, now yes we have a way of reversing that process by removing the build up, but it still shows continious leeching. I think we need to stick to a finer substriaght but oothlic sand I believe is going to be far to fine and will pose problems with diffusion. Here is where a comprimise is needed. The media should be fine enough to allow for even diffusion from us sucking water through it , but still must have the ability to form anaerobic zones in its lower depths easily.


Mike

 

[Curtswearing]

I did some googling on aragonite sources and found that most of the larger particle sources included a lot of crushed shells as well. The shells typically dissolve and throw a lot of Phosphate into the water so I wasn't liking that one bit.

Thinking of particle size and the Phosphate issue, I was thinking that A.R.M. media might be useful for people with SMALL tanks (due to price).

CaribSea A.R.M. Calcium Reactor Media is processed for immediate use, no rinsing required, and has double the surface area of regular aragonite. Precision grading (2-3mm) allows for maximum carbon dioxide penetration, and the exclusion of gastrpod shells insures the lowest phosphate and silica (about 1/2 that of other brands) content. This grading also carries in the highest concentration of Halimeda incrassata, an aragonite so pure it has been used as a laboratory standard.

That had some merit in my mind. The particles are big enough that we shouldn't have too much melting. The media obviously isn't going to stay Phosphate free because the detritus will break down and the Phosphates will adsorb onto the media instead of going back into the water column. However, the particle size at 2-3 mm still seems too small. I was wondering if someone who owns this media has a digital camera and could post a picture of a small pile of this. I'm having a difficult time picturing how big the particles are and how big the spaces between the pieces would be.

Does anyone know any sources of crushed coral that doesn't contain shells?

 

[Witfull]

whats the PO4 content in dolomite?