# Aesthetics vs. anaerobic subtrate



## Michael (Jul 20, 2010)

Hello everyone,

I am planning my first El Natural aquarium. In fact, it will be the first aquarium I have done in about 30 years!

In looking at a lot of aquascapes, I admire the "topography" that some of the Japanese-inspired designs achieve with stone and deep substrate. But I know that the deepest substrate recommended for El Natural is about 2"--1" of soil and 1" of cap.

Is there a way to get the topography without causing anaerobic conditions in the soil layer? For example, could you start with bottom layer of inert material (gravel or whatever), build that up to within 2" of the desired final surface, then put a 1" layer of soil and a cap over that?

Thanks for this forum, I have learned so much just reading over the last few months.

--Michael


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## jclee (Aug 24, 2009)

I don't think gravel would work. I'm pretty sure that anaerobic bacteria forms when decomposing waste and debris is trapped in the substrate, and water circiulation/movement can't reach it to gas out. I think. This can happen in deep gravel, too. I wonder if you could look into using eggcrate to make a false bottomed tank, like people use for vivariums.

I think this thread has a discussion of how to do that: http://www.vivariumforum.com/community/terra-construction/1542-vivarium-paludarium-im-new.html


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## Michael (Jul 20, 2010)

Thanks for the link! I will definitely spend some time reading there.

The eggcrate won't work for what I have in mind, but I could use larger pieces of rock or some other solid inert material to make the bottom layer of the deep areas. This wouldn't leave any voids for waste to settle into, and maybe prevent growth of much anerobic bacteria.

I'd love to read any other thoughts or suggestions.

--Michael


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## Emily6 (Feb 14, 2006)

I agree that large rock pieces might be your best bet. In fact, I've read that is how Takashi Amano achieved some of his landscapes. It's also cheaper than filling that same space with substrate or what have you. 

Whatever you use, remember that you (ideally) will never see it again until you tear down the tank. So you don't want anything that decomposes, leaches tannins, or can host grime. I suppose that's a little obvious, though.


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## Michael (Jul 20, 2010)

I just realized that I have lots of ceramic tile scrap from a remodeling project. It would be easy to layer this to exactly the right height, then put the soil over it. It is high-fired tile, so it should be inert and not porous.

--Michael


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## mauve (Apr 20, 2010)

the is no reason to be afraid of "anaerobic conditions" in the soil layer.
here is a nice excerpt from a site that is a very good source of info.

-"A number of people have expressed concern that this substrate is very anaerobic (lacks oxygen). Actually, all substrates are anaerobic including gravel. The mud that plants grow in, in nature, is also anaerobic. Plants deal with this by forcing small amounts of oxygen through the roots. This allows for aerobic types of good guy bacteria to grow around the roots."


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## Michael (Jul 20, 2010)

Mauve, from repotting waterlilies in my pond I know that this is true. But I also observe that even very large, vigorous plants with emersed foliage like waterlilies do not send roots very deep into the container of soil unless the container has lots of holes to allow gas exchange. I don't use more than 6" of soil in my waterlily pots because that is about as deep as the roots will grow. To compensate for shallow soil, I use wide, flat containters.

I think the other concern about anaerobic substrate is the effect on the animals in the aquarium. In my ponds, the soil volume is small relative to the water volume. In an aquarium with a soil substrate, the ratio of soil to water volume is a lot greater. If the anaerobic soil starts generating H2S or methane, there isn't much water to dilute them.

--Michael


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## Tex Gal (Nov 1, 2007)

We have all seen the bubbles coming up from our soil when we pull us a crypt or something. We've all smelled the rotten smell. I've seen what it can do to bulbs. I guess you could wonder what came first the rotten bulb or the rotten smell. I believe the roots rot if your soil doesn't breathe well enough. I try to keep my soil aerated by snail or poking it. I do a fair amount of replanting in some areas so it naturally gets moved around. I also use root tabs in the plants that are in permanent places so that causes some aeration when I insert the tabs. 

I use rocks to raise the level. I've never done a steep hill though. I also thought of filling different size plastic bottles with water and piling substrate on that. You could also use lava rock. It's light and not super expensive.

I was in Houston at ADG and saw Mike Senke's tank. His background hill was at least 10" deep. It was all ADA AquaSoil. He had wonderful grass on it. He said he had no anaerobic problems. I don't know how long it had been set up.

I always think filler material is cheaper than substrate and then you don't have to worry.


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## HeyPK (Jan 23, 2004)

I have never had problems with soil substrates or even soil-peat mixture substrates. They become anaerobic, but the plants have air channels in their roots and stems, and since oxygen diffuses something like 100,000 times faster through air than it does through water, the root cells have access to oxygen, and oxygen diffuses out through the roots providing an oxygenated zone around the roots. The ability of aquatic plants to live in anaerobic soils was really put to the test by a guy who wrote an article a long, long time ago in The Aquatic Gardener called, Here's Mud in Your Tank. He mixed 1/3 topsoil with 2/3 manure, and the manure was fresh out of the cow. Without letting it compost he immediately put this steaming mix in pots in his tank and planted sword plants in it. He reported that the sword plants grew well. This is a substrate with a far greater biological oxygen demand than anything normal in the plants' environment, and yet the plants were still able to live in it. He did say that this substrate bubbled a lot. If I were to use a manure-soil mix, I would let it compost in a covered storage box for a week or two so that the easily broken down organic compounds with high oxygen demand would all get broken down and only slowly decomposing, resistant organics would be remaining. Often composted mixes like that will bubble a lot when submerged, but this bubbling is mostly harmless nitrogen gas as nitrates released during the composting get reduced by bacteria to nitrogen gas. 

Anaerobic soils actually are useful for plants because oxidized iron compounds, which are insoluble, are reduced, making them soluble and available. In fact, I have often found, when growing a plant in a tray of soil, that, when the plant roots fill the tray to the point where none of the soil is anaerobic any more, the plant begins to show iron deficiency. Having peat or manure in the soil makes it last longer for the plant.


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## Tex Gal (Nov 1, 2007)

I have never had any fish die from the gasses. I have had bulbs rot. Maybe HeyPk is right. It was the bulbs that rotted first. Who knows. I just try to avoid the issue.


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## HeyPK (Jan 23, 2004)

The only bulb plants I know of are Crinum, and I have never had experience with them. They may not be able to handle substrate with a large biological oxygen demand. They mostly live in streams, don't they? Streams always seem to have low organic content in their soils unless they are very slow moving.


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## Coconutboy (Apr 13, 2007)

Another alternative would be Malaysian Trumpet Snails.
I really don't have much experience with them, but from what I've read they bury themselves into your substrate and eat the detritus. The movement under your substrate may also help with aeration.

I've never really worried about anaerobic conditions in my NPT though.
As someone said previously, most plants squeeze oxygen downwards into their roots.


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## davemonkey (Mar 29, 2008)

+1 on the trumpet snails. They do a good job stirring the soil, BUT this can be a headache if you are trying to maintain a certain slope or terrace-effect. Their activity will speed up the leveling-out of you substrate, but they do a good job keeping it "alive".

Oh, and I've also never had a problem in my NPT's with the anaerobic soils. 

-Dave


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## jclee (Aug 24, 2009)

I use MTS in my NPTs, and I was also thinking about live blackworms. I would think they'd be more effective than MTS, and they'd be a great occasional snack for the fish. They shouldn't be able to overpopulate the tank unless you were overfeeding. I wonder what other beneficial, non-fish, tank additions people add to their tanks that I'm not thinking of.


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## Supercoley1 (May 28, 2007)

This is quite a coincidence. I was just reading a thread on ASW which got onto the subject of anaerobic conditions and basically all of the above suggesting _no problems_ are correct 

Plants use a process called 'aerenchyma' whereby they diffuse O into the substrate which nitrifying bacteria can feed off and do what they do in the rest of the tank. Turn bad stuff into good stuuff 

By the time a substrate is breaking down the plants' roots should be extremely well established and be a complete oxygenating system on their own within the substrate without the need for the 'clean up crew' at the substrate's surface.

At the end of the day 2 of the biggest brands (ADA and Tropica) and countless others use a complete clay substrate albeit ADA admittedly do 'feed' the anaerobic debate by marketing Powersand in conjunction with the clay to 'avoid' anaerobic conditions. Clay substrates tend to break down into mud after a while.

Huge swathes of people use ADA AS on its own or Tropica (admittedly the majority in short term term scaping) but many including myself (Tropica) use it for a 'permanent' base with no problems. I don't even do the Tom Barr suggestion of stirring it up every year or so (although I think he is suggesting that to 'appease' the non believers when no water changes are suggested.)

My El Natural has a 3 year old 4" substrate which is basically 2" clay (Tropica) with 2" very very fine sand (play sand) and I have no problems at all. It has been El Natural since September 2009 with zero water changes since (10 months and counting.)

Before that it was pressurised CO2, EI dosing and 50%+ weekly changes.

As a hi-tec or El Natural, this tank has never seen a 'vacuum' or been interfered with in any way other than the inhabitants doing their 'levelling' job. 

Loads of Crypts in the tank BUT 50% or more of my plant mass is above the substrate, not floating but rhizome plants (Anubias, Ferns etc. However Crypts are huge 'rooters' and therefore remove all worries for me. 

I always plant Crypts around the base of hardscape to let the roots get underneath as I remember how yucky a sand substrate looks in a non planted tank when you remove some hardscape. Black discoloured sand and an instant egg bomb. :lol:

On the trumpet snails I must say that they don't 'bury' themselves deep in the substrate. Much of their use is like that of sand sifters, bottom feeders and shrimps in that they are clean up crew. they 'patrol' the upper part of the substrate (maybe an inch or less) and consume detritus, rotten matter, left over food etc and minimise what goes down to the lower parts of the substrate.

All in all you can find 'evidence' and hearsay to support both sides of the argument so it is down to you, the tank owner, to make the final decision of what to do and it may be that you choose to be precautionary.

AC


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## Michael (Jul 20, 2010)

Supercoley, is the Tropica substrate a calcined (fired) clay? I've never seen it; how large are the particles?

--Michael


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## Supercoley1 (May 28, 2007)

Michael said:


> Supercoley, is the Tropica substrate a calcined (fired) clay? I've never seen it; how large are the particles?
> 
> --Michael


Its not fired (I think) it is quite soft like wet sticky sand. Goes under a 'cap' which gravel is suggested but I always use playsand. I guess sizewise the particles in the pic below about to be coverd by sand are a 'nominal 5-10mm. (1/5 to 2/5 inches)

This is the current substrate 'going down'. Tropica on the left and playsand on the right. This picture is dated 19/09/07!!! Nearly its third birthday :lol:

(For anyone who doubts the age then click on the phot header and then right click. you can see the date in the image properties. lol)









AC


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## Michael (Jul 20, 2010)

Interesting, it sounds a lot like akadama, a type of clay soil used for bonsai.


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## Supercoley1 (May 28, 2007)

yeah pretty similar. high CEC, not nutrient rich (from the bag.) It soaks up nutrient as it goes along so it sweeps up 'overs' and saves them for a rainy day 

It is the white and blue bag in this picture. the 'Soil builder' next to it is Earthworks' 'product name' for plain Leonardite (older than coal) a source of slow release Carbon which goes under the Tropica. I still have half that tub left. lol. Then under the Leonardite is of course......mulm. I just pured the filter water from the previous scape (taken down a few hours earlier than these pictures) and squeezed all the dirt from the filter sponges.

Soon as the substrate was in the equipment was setup, tank filled up and the fish were acclimitised next morning when the tank was up to temp. No messing around 










AC


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## Tex Gal (Nov 1, 2007)

HeyPK said:


> The only bulb plants I know of are Crinum, and I have never had experience with them. They may not be able to handle substrate with a large biological oxygen demand. They mostly live in streams, don't they? Streams always seem to have low organic content in their soils unless they are very slow moving.


The bulbs that rotted for me were Aponegetons. I have had it happen to three different varieties.

Such an interesting discussion. I haven't had fish die but I think the smell was enough to concern me. What I understand you all saying is that the smell is JUST a smell and same with the air bubbles. These conditions should not hurt either flora or fauna. Very interesting!!!


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## lipadj46 (Apr 3, 2011)

Tex Gal said:


> The bulbs that rotted for me were Aponegetons. I have had it happen to three different varieties.
> 
> Such an interesting discussion. I haven't had fish die but I think the smell was enough to concern me. What I understand you all saying is that the smell is JUST a smell and same with the air bubbles. These conditions should not hurt either flora or fauna. Very interesting!!!


A bit of an old thread but I disagree. I had play sand go anaerobic and roots will turn black and rot and take out the plant. I have switched to pfs


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## Michael (Jul 20, 2010)

I am surprised that this thread has come back to life.

To let everyone know what happened, I set up the tank just as described in my last post: layers of ceramic tile on the bottom, soil over that, and expanded shale as a cap. It worked! The tank is flourishing and can be seen my journal, Hidden Spring.

Honestly, I don't think the ceramic tile was necessary. I set up another tank about 6 weeks ago in which I put the soil (MTS in this case) on the bottom and made the cap deeper in some areas to get the topography. The cap is natural aquarium gravel in part of the tank, and Soil Master Select in the rest. This tank is in the Journal: Tributary on the DFWAPC forum.

In both tanks the substrate will ocasionally release a bubble or two. There is no odor, and fish and plants are healthy.


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## Rusalka (Jun 11, 2008)

i had a tank set up for 3 years with deep soil and it bubbled and smelled all the time. for the last year or so i had a bunch of fish deaths, so though that my anaerobic substrate was it was harming my fish.

so when i moved a year ago i tore down my tank and started fresh with a better setup - and it turns out my fish (guppies) kept dying. they had contracted MB from a plant or snail. it wasn't poisonous anaerobic gas killing them. MB deaths still occur but have slowed since i am more conscious about removing fish as soon as they show symptoms. 

I do think that an anaerobic substrate does stress the fish - but if they are healthy, it's not a problem. I think that's another reason why my MB infected fish are tougher than before.


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## f1ea (Jul 7, 2009)

Wow... kinda an old thread. This was here? hehe

I have used foam and rocks/slate to build a slope, then top with the ussual soil+capping.
Using foam you have to make sure the rockwork and hardscape put enough weight on the foam structure or it will FLOAT and make a soil gravel mess!! Now i test the harscape in advance by filling up the tank without soil/capping. 

You can go deeper than 1" of soil if you have good hard rooting plants like echinodorus, crypts even some of those heavy-rooting stem plants. Anaerobic substrate is not as evil as it sounds.


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