Rubble Rock

[Pumped]

Isn't Rubble in the fuge the same thing as bio-balls? Won't it produce nitrates?

[isildursbane]

No. Any media where bacteria can colonize will act like bio balls and convert nastys to nitrate rapidly only if exposed to air. Hence the term Wet-Dry filter. That is how bio-balls work, the bacteria need lots of oxygen for that conversion.

Here is a link where you can read RC articles on filtration. In Natural Filtration 1, 2 or 3 the author talks about people using LR in a Wet-Dry filter and why that is bad.

http://www.reefcentral.com/forums/showthread.php?t=1696795

[jeff@zina.com]

Isn't Rubble in the fuge the same thing as bio-balls? Won't it produce nitrates?

Depends. Is it a wet/dry rubble or submerged, like live rock? It's the wet/dry part that holds nitrates and eventually over-saturates, releasing them back to the tank.

Jeff

[Palting]

YES.

This thing about air exposure is a classic and common misconception about the aerobic process. Otherwise, you can just submerge the bioballs, and you'll be OK. Aerobic process, the conversion of ammonia to nitrate, does NOT mean it can only happen in exposed open air. Aerobic processing means that there is sufficient OXYGEN, not air itself. And there is dissolved oxygen in water. For you to have the anaerobic process, the conversion of nitrate to nitrogen gas, you have to have a HYPOXIC zone. Simply being under water does not give you a hypoxic zone, especially if you have the water flow you are supposed to have. You need depth, where the oxygen is consumed by the superficial bacteria, creating the hypoxic conditions in the deeper area.

Rubble, due to lack of depth, is the same as bioballs. You need real rock with depth, not rubble, if you want to create a hypoxic processing zone.

The reason rubble in the fuge is acceptable in the current thinking, is that the nitrate produced is produced right there where the macroalgae can consume the nitrate. Simillar to the live rock, where the nitrate produced by the superficial bacteria is produced right there immediately adjacent to the deeper regions where it can be processed by the anaerobic bacteria.

[Uncle Salty 05]

NO.
Most refugiums have low flow allowing for longer contact time for the macro to absorb the nutrients in the water.
Live rock rubble piled in an area of low flow will create a very low oxygen zone and provide a good place for pods to reproduce.
And depending on how porous and deep the rubble is can carry a ton of anaerobic bacteria.
The difference between bioballs and LR rubble in a fuge is like night and day.

[Palting]

OK. Just to continue my education, then, since I readily admit I'm a noob too. Live rock rubble to me are rocks about the same size as bioballs. Stones, realy, rather than rock. If I pile up bioballs in a low flow area, simillar to the pile of rubble, will I have a low oxygen zone deep in the pile of bioballs?

[Uncle Salty 05]

OK. Just to continue my education, then, since I readily admit I'm a noob too. If I pile up bioballs in a low flow area, simillar to the pile of rubble, will I have a low oxygen zone deep in the pile of bioballs?

At the bootom the pile, maybe.
Bioballs are specifically designed to allow flow through them.
Live rock rubble is not.

[Palting]

At the bootom the pile, maybe.
Bioballs are specifically designed to allow flow through them.
Live rock rubble is not.

Thanks! Clarifies it for me.

[thegrun]

I'm going to take Uncle's side on this debate, assuming the "rubble" is both porous and in the neighborhood of 1" diameter or bigger (not gravel). The problem with submerged bio balls is that it traps detritus and since it is not porous, it does not host anaerobic bacteria. Porous rock does produce anaerobic zones which help reduce nitrates.

[Uncle Salty 05]

Thanks! Clarifies it for me.

You're welcome.
I've got to start spell checking! :beer:

[Palting]

I am still developing my fund of information here. So, let me see if I can expand it some more. Let me know if I'm wrong. Hope I am not wearing out my welcome here :).

If you have a small area, as in those HOB filters, where you have no choice but to use rubble, then the porousness of the rubble and it's lack of "designed for flow" character gives it the opportunity to develop hypoxic zones, unlike bioballs. My impression, though, is that it is only marginally better than bioballs as it sacrifices some ammonia processing (less flow through, less aerobic) to get the nitrate processing. Would it not be more efficient to use the bioballs that the HOB was designed for and process the ammonia more efficiently, and then provide a separate refugium with macroalgae to take care of the nitrates produced?

I can't support the argument that bioballs are more of detritus traps than rubble. They both trap detritus, just process them differently. Right?

If you have a large area, say a 5 gal refugium, wouldn't it be senseless to use rubble with large surface area relative to weight and therefore more aerobic, when it would make more sense to use the biggest pieces of porous rock with less surface area per weight unit you can find and have a better chance of developing hypoxic zones?

[Uncle Salty 05]

Not at all, the only dumb question is the one you don't ask.

A pile of live rock laying in a refugium with low flow,a fine substrate that you can partially bury it in, surrounded by macro which further lowers the flow around the rubble and a pile of rubble in an HOB filter with high flow are two very different scenarios.
In my experience bioballs do not trap detritus. When I removed mine to replace them with base rock they were as clean as the day I put them in.
They just produce nitrate quicker than your LR and sand can process it.
While a bigger piece of live rock would process ammonia better (that is the purpose of the LR in the DT) the rubble provides ideal places for copepods, amphipods etc. to call home.
Any HOB refugium will not perfom as well as a stand alone refugium due to much smaller substrate surface area, limited space for macro and pods to flourish and in most cases too much flow.
Intense lighting is also very important for a refugium, you want nearly 10 watts per gallon on a fuge.
When those DT lights go out you want that macro producing as much oxygen and taking up as much CO2 as possible. This is what helps keep your PH stable.

[mgoblue]

My new tank setup will have a detached refugium and I have no experience with them, so trying to learn as much as possible.

I am afraid of DSBs, and I am leaning away from lots of rubble in my 'fuge for the same reasons. The 'fuge will be about 10g . I had planned on using it mostly for chaeto and only have 2-3 baseball size pieces of LR in it for additonal pod habitat.

My DT is a 75g that will have a SSB (80# pink fiji aragonite) and only enough rock to provide the aquascape look that I like (somewhat minimalistic - probably 2 medium islands, I'm guessing 50# or so).

I also plan to run a Phosban reactor from day one.

My thinking is that I should have enough surface area for the breakdown of ammonia and nitrite, and between the chaeto and weekly ~10% water changes, I should be okay on nitrates.

Am I all wet?

[isildursbane]

My thinking is that I should have enough surface area for the breakdown of ammonia and nitrite, and between the chaeto and weekly ~10% water changes, I should be okay on nitrates.
Am I all wet?

We would have to know the proposed bio-load of your matured tank. Hard to say really. There is nothing wrong with going minimalistic. I would not be afraid of a DSB or lots of LR and/or LR rubble in the fuge. Also, I would assume you plan to run a skimmer. The skimmer is what pulls the proteins out of the water before your bacteria colony has a chance to break it down through the N cycle to Nitrate. That is the point of getting a good skimmer and why wet-dry/bio-balls are not recommended anymore.

[thegrun]

My new tank setup will have a detached refugium and I have no experience with them, so trying to learn as much as possible.

I am afraid of DSBs, and I am leaning away from lots of rubble in my 'fuge for the same reasons. The 'fuge will be about 10g . I had planned on using it mostly for chaeto and only have 2-3 baseball size pieces of LR in it for additonal pod habitat.

My DT is a 75g that will have a SSB (80# pink fiji aragonite) and only enough rock to provide the aquascape look that I like (somewhat minimalistic - probably 2 medium islands, I'm guessing 50# or so).

I also plan to run a Phosban reactor from day one.

My thinking is that I should have enough surface area for the breakdown of ammonia and nitrite, and between the chaeto and weekly ~10% water changes, I should be okay on nitrates.

Am I all wet?

I would add a little more rock to the bottom of the refugium, both for added biological filtration and to prop up the cheato. If the cheato sits under too much water, its growth slows down. I've found that keeping it near the surface with live rock below is the best way to promote growth. Take the live rock up to about 6"-7" below the surface of the water and then fill the remaining space with cheato.

[Uncle Salty 05]

Not sure what you mean by "detatched". It must be tied to your DT or it will not affect anything.

1 to 2" of your fine fiji pink is all you need, just enough to allow your macro to take root. (I like Kent's biosediment mixed in)
And remember you want the drain from your fuge to your sump to bypass any mechanical filters so pods can be fed to your DT.
Don't fear a little pile of rubble, it is your (and your pod's) friend.

[cloak]

NO.
Most refugiums have low flow allowing for longer contact time for the macro to absorb the nutrients in the water.
Live rock rubble piled in an area of low flow will create a very low oxygen zone and provide a good place for pods to reproduce.
And depending on how porous and deep the rubble is can carry a ton of anaerobic bacteria.
The difference between bioballs and LR rubble in a fuge is like night and day.


When I think of rubble, I think of golfball sized rocks or smaller. I don't think your going to get the added benefit of anaerobic bacteria with rocks this size. It might happen, but the odds would not be in our favor IMO. There really no different than the untouched glass.
I don't really see how flow would play a role either. Low flow, high flow, things can't be so different in a pile of rubble in the corner, whereas 6 inches away things are circulating much faster. It's all one body of water, if it's moving, it's moving. It almost sounds as if there's a bubble that can't be popped.

[mgoblue]

We would have to know the proposed bio-load of your matured tank. Hard to say really. There is nothing wrong with going minimalistic. I would not be afraid of a DSB or lots of LR and/or LR rubble in the fuge. Also, I would assume you plan to run a skimmer. The skimmer is what pulls the proteins out of the water before your bacteria colony has a chance to break it down through the N cycle to Nitrate. That is the point of getting a good skimmer and why wet-dry/bio-balls are not recommended anymore.

Yes, I will be running an Octopus DNWB-110. It's rated at 125g, so I think it would be fine on my 75g. I know a lot of people recommend 2x the DT, but I have seen good reviews that say these are rated closer to actual capacity and not padded like some.

[mgoblue]

Not sure what you mean by "detatched". It must be tied to your DT or it will not affect anything.

1 to 2" of your fine fiji pink is all you need, just enough to allow your macro to take root. (I like Kent's biosediment mixed in)
And remember you want the drain from your fuge to your sump to bypass any mechanical filters so pods can be fed to your DT.
Don't fear a little pile of rubble, it is your (and your pod's) friend.

Detached was probably a bad choice of words. I meant separate from the sump. I plan to divert a percentage of the return water to the 'fuge and the overflow of the fuge will go to the return section of the sump.