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View Full Version : Highly porus media vs LR when Org. Carb. Dosing.


AaronM
07/21/2010, 07:40 AM
I have an OHF filter atm which sucks, but i'll push my question out further than my case...

A large amount of LR, both in tank and as rubble in fuge or OHF, is generally promoted because of the anaerobic bacteria it can house which break down nitrate into nitorgen.

When OCD we are feeding aerobic chemoorganoheterotrophic bacteria, correct? *choke*

As these heterotrophs are areobic, which they clearly are as they colonise the glass and cover the rocks where they have access to oxygenated water, does it make sense for OCD tanks to shift some focus from large amounts of LR in the fuge and OHF to highly porus media pellets? Less natural i know, but maybe more effective when OCD?

For ppl who want more open aquascapes and are concerned about reduced bio filter that comes with less rock, would OCD + lots of high porus pellets be a reasonable alternative?

In my experience adding more LR, i.e anaerobic housing, was less effective in reducing nitrate that boosting areobic heterotrophs.

I guess my question is, assuming good export re. the areobs we're feeding, does it make more sense to consider areobic housing over anaerobic?

:) More specifically for me, is high porus pebbles or LR rubble better in OHF when OCD?

Thanks for opinions/help...

Lemeshianos
07/21/2010, 08:56 AM
I think we are feeding hypoxic bacteria when OCD. The reason we see bacteria blooms is because of the tabling of the pellets/rice/etc in order for the bacteria film to leave the surface of the media for 2 reasons:
1. For new bacteria to take their place and consume nitrates.
2. For bacteria to get skimmed out of water by the skimmer.

feel free to correct me if I'm wrong.

AaronM
07/21/2010, 10:02 AM
I'm only trying to figure out...
By hypoxic you mean anaerobic. I think see what you're saying, but if OCD feeds anaerobs, then blooms would occur in oxygen free areas, such as deep in LR and sandbeds. As OCD causes visible blooms e.g on the glass, without much understanding, leaning on observation, i think the bacteria increased are areobic. (brace for impact?)

1) If the bacteria are blooming on the surface, i.e exposed to aerated water, then aren't they areobic? Wouldn't increased surface area allow for more bacteria to grow, be skimmed out, and replenished
2) ATM i have to image this bacteria prefer to layer on surface, but isn't limited to, and re. surface can break away esp. when layering on self, blown off, dying, disturbed, and after this = skimming removes. So kinda back to my question, wouldn't giving maximum surface area, e.g high porus pebbles as well as glass and rocks, promote more living space, more mass, higher uptake of nutes and assuming good export, better reduction of nutes?

Lol everyone feel free to correct me if i'm wrong too.

Stuginski
07/21/2010, 04:36 PM
Hi Aaron I share with you the same doubt ... and would be happy if someone elucidate this.:beer:
I believe that the dosage of carbon sources are useful for all the bacteria. But when we see these large bacterial bloom that usually comes along with the reduction of nitrates, I believe they are caused primally by aerobic bacteria, otherwise we would not have decreased levels of oxygen, it isnīt right?:confused:
So why do we insist in use anaerobic layers to denitrification? Does aerobic bacteria alone would not do this?:hmm4:

I hope that someone clarify me...

Hails from Brazil


D.

bertoni
07/21/2010, 05:26 PM
Well, the carbon dosing could feed both aerobic and anaerobic bacteria. We don't really know how live rock works, so it's hard to say what carbon dosing will do for it. It's possible that the dosing feeds a two-layer bacterial culture, for example, with the interior cells living on anaerobic processes, or the denitrification could be done by facultative anaerobic bacteria or even endosymbionts.

I think it's reasonable to try using pellets or something like SeaChem De*Nitrate (artificial pebbles) in place of try live rock if a more open tank is a goal. I think that's true whether using carbon dosing or not, though.

Stuginski
07/22/2010, 12:17 AM
Hi Jonathan itīs good to see you here in this topic too!!!!:thumbsup:

In my previous topic iīm asking how can I multiply the area destinated to anaerobic bacteria to better results in my denitration process...in that post I agree 100% with you that some porous midia will work better than my stupid idea to make solid rocks porous!!!:thumbsup:

But minutes after start that thread I saw this one from our friend Aaron...and this really makes me think...When we dose vodca...or other carbom source to our tankīs WHO is the bacteria that are really working reducing nitrates and phosphates???? I have to agree with Aaron that the most part of the bacteria skimmed apparently are aeroibic ones....another fact is that we generally have much more area for aerobic bacteria... this make me think that...IF the nitrates and phosphates reduction with vodca method occurs because bac uses the carbom source and nitrate to multiply...itīs reasonable think that the skimmate represents this bacteria...and itīs reasonable think that almost everyone bac in this skimate are aerobic or at least facultative. So after this comes questions:

1- What kind of bacteria really bloom after carbon dosing?
2- Systems with no anaerobic area could have the same benefits with carbon dosing?
3- Some aerobic bacteria that represents a little fraction when compared to anaerobic bacterias in terms of denitrification...could after carbom dosing...multiply and start to represent the major portion of this work?
4- In other words.....anyone knows what kind of bacteria are responsible for reduction in nitrates and phosphate when we add carbon sources???????????????


Hails from Brazil

D.

Genetics
07/22/2010, 08:45 AM
1- What kind of bacteria really bloom after carbon dosing?
2- Systems with no anaerobic area could have the same benefits with carbon dosing?
3- Some aerobic bacteria that represents a little fraction when compared to anaerobic bacterias in terms of denitrification...could after carbom dosing...multiply and start to represent the major portion of this work?
4- In other words.....anyone knows what kind of bacteria are responsible for reduction in nitrates and phosphate when we add carbon sources???????????????

Always a fun and in-depth conversation to philosophize about.

1- No one really knows.
2- People that run barebottom tanks have sometimes run into problems where no matter how much OCD they add to the tank they cannot see a nitrate reduction. What this hints at is there is a surface area requirement or there is a need for differing layers of aerobic and anaerobic bacteria.
3- When new food sources are introduced, a change in the food web can be expected. I do not see why new bacterial populations may become more prominent.
4- I don't think that has been elucidated.

Further expanding on #2, recently longer OCD polymers have come to market that are not water soluble but can be broken down by bacteria. These 'plastics' are found with increasing use and seem to achieve similar results. They work well in a tumble fashion in reactors with decent flow which would keep them oxygenated. However, similar setups used anaerobic conditions to reduce nitrates. So, my guess is the answer is relatively complex.

AaronM
07/22/2010, 09:22 AM
I believe they are caused primally by aerobic bacteria, otherwise we would not have decreased levels of oxygen

Thats something i thought too.

O.k, the categories of bacteria are overwhelming. More pointers to wiki. When overdosing OC one quickly sees white whisps on the rocks, layering on the glass, cloudiness in the water. These effects are associated with sharp drops in nutrients. If anaerobs were doing the work, then sharp drops wouldn't be associated with these visble signs. Based on this, its reasonable to conclude that the workhorse is aerobic.

If the workhorse is aerobic when OCD, then providing maximum surface area exposed to aerated water would be desired, so i was thinking high porus bebbles would work better than LR.

hmmm...yeah LR + bacteria = more complex than inner and outer...

I thought these pebble were better for amomnia to nitrite, nitrite to nitrate. So having alot of these pebbles isn't useful after the tank has cycled. I thought having these pebbles, say with open scape, is pretty much useless. Ofcourse having lots of LR outside DT is useful period. I thought OCD boosts aerobs, and as high porus pebbles houses aerobs, it'd make sense to have lots of pebbles

Do you guys think a tank could maintain low nutrient levels without any liverock, a few fish, and with high porus pebbles? high nitrate?

Do you think a tank would be o.k with no liverock, some fish, OCD and high porus pebbles?

Genetics
07/22/2010, 09:44 AM
[B]
Do you think a tank would be o.k with no liverock, some fish, OCD and high porus pebbles?

Yes. Actually, using the Berlin method having a lot of surface area (in the form of LR), some fish, and a skimmer was high tech a decade ago and gave great results to people that didn't overload there tank.

bertoni
07/22/2010, 02:16 PM
I often wonder whether tank filtration often ends up limited by surface area. That's possible to test to some degree, with something like De*Nitrate.

Stuginski
07/22/2010, 10:13 PM
It would be very usefull if some marine microbiologist determine which bacteria are trully working for us! The possibility that aerobic bacteria rather than anaerobic bacteria are the most important bacteria to reduce nitrate in nitrogen when we dose some carbom...could be change many things.

Best regards

D.

thebanker
07/23/2010, 02:39 AM
Cool... I've often wondered if De*Nitrate could be used in place of more LR to help with a higher bioload & heavy feeding.

So assuming you're dosing vodka, sugar or emulsified polycaprolactone like Instant Ocean Natural Nitrate Reducer... What kind of flow would make De*Nitrate effective? I would think low flow would be best, but maybe high flow could work well. And would it be beneficial to periodically "stir the rocks" like zeovit?

AaronM
07/23/2010, 06:31 AM
It would be very usefull if some marine microbiologist determine which bacteria are trully working for us! The possibility that aerobic bacteria rather than anaerobic bacteria are the most important bacteria to reduce nitrate in nitrogen when we dose some carbom...could be change many things.

Yeah i agree! But i reckon there are so many variables affecting what bacteria each of us have. In theory, set up a number of tanks with liverock all from different sources, dose, and see what blooms. But then in reality we all don't just have different rock, theres different fish food, fish, coral, flow, etc, which might affect what bacterias doing the work. Still, surely theres some usual suspects, or at least categories of...

It's possible that the dosing feeds a two-layer bacterial culture
"As with reef rock, anaerobic conditions are achieved by the porosity and the depletion of oxygen by the aerobic process at the surface." From http://www.seachem.com/Products/product_pages/denitrate.html

Just wanted to show what caused a another click for me.

The bloom in aerobes may cause a bloom in anaerobs...and facultative aerobes...which is all part of the desired process.

Genetics, yeah...i guess OCD is a method, like berlin, that can be used with or instead of/replaces.

Bertoni, you've mentioned de*nitrate a few times. I discounted this product...because i thought in my OHF part of AR-980, it wouldn't work...what with all the splashing around. Now, considering click, not sure. Now it seems to me LR rubble or de*nitrate or straight high porus pebbles = much of a muchness. With straight high porus, like eheim substrate pro, maybe the hugely increased aerobic masses when OCD creates places for anaerobs anyway. Because of this, starting to seem like OCD is more versatile than berlin. Still, which do you guys suspect is better when OCD, LR, de*nitrate, or straight porus, even if marginally?

So assuming you're dosing vodka, sugar or emulsified polycaprolactone like Instant Ocean Natural Nitrate Reducer... What kind of flow would make De*Nitrate effective?

I have that question too. For me, is VERY low flow rate effective?

Thanks alot for the help. :) frustratingly fascinating.

bertoni
07/23/2010, 03:36 PM
The De*Nitrate should have enough flow to prevent the water column from become anoxic. Beyond that, it's very hard to know what kind of flow will work. A wide range might be quite acceptable, although different flow rates might lead to complete different species of microbes on the rock. Sorry, I just have no data to suggest what will work.

I hadn't read that SeaChem page, but that's along the same general lines that I was considering.