# Lava Rock in substrate?



## roadmaster (Nov 5, 2009)

Beneficial aerobic bacteria are only found in first few centimeter's of substrate where oxygen is greater than deeper in substrate, where anaerobic bacteria are found.
Two inches of soil (dirt cheap ha! ha!), with three inch cap of fine gravel or sand would be my move.


----------



## hivemindhermit (Oct 19, 2017)

I've been thinking something similar: Putting lava rock, LECA or some similar lightweight, inert substrate _under_ the soil layer, maybe mixed with a bit of clay for long term mineral supply. With little organic material in the bottom-most layer, anaerobic activity should remain minimal, no? This bottom layer would also support hardscape.

(I'm also experimenting with mixing my soil with LECA and gravel, to make sure it doesn't get compacted under the weight of my sand cap.)

Of course one could also simply raise the hardscape by attaching it to something like styro (which would have to be glued to the bottom of the tank). 

Sent from my Pixel using Tapatalk


----------



## Nigel95 (Mar 5, 2017)

I would use lava split. This is lava rock with a size of 2-8mm. Benefit is that it will last permanent (soil will crush over time) and keep the hardscape better together. On top of the lava split some soil.

Lava split is also cheaper than soil 

https://www.azaqua.nl/en/nutritional-base/1935-lava-split-2-8mm.html

or something like jbl proscape volcano.


----------



## roadmaster (Nov 5, 2009)

I have mixed soils with all kinds of stuff Osmocote,cat litter, peat,green sand,azomite,worm casting's in small amount's ,but always capped the mix with fine gravel or sand and once planted with plant's,left them alone.
Was not always keen to place fishes in them for fear of organic matter leaching from the substrate if disturbed into the water column, and producing ammonia levels that might be harmful to them,and trigger for algae(with too much light), but it gave me chance to see how plant's reacted.
The cap I feel,provided a slower release than maybe otherwise.
If I wanted to experiment with substrate mixes , I might not want to experiment with my fishes for a few weeks/month's.
Opinion's vary.


----------



## hivemindhermit (Oct 19, 2017)

roadmaster said:


> I have mixed soils with all kinds of stuff Osmocote,cat litter, peat,green sand,azomite,worm casting's in small amount's ,but always capped the mix with fine gravel or sand and once planted with plant's,left them alone.
> Was not always keen to place fishes in them for fear of organic matter leaching from the substrate if disturbed into the water column, and producing ammonia levels that might be harmful to them,and trigger for algae(with too much light), but it gave me chance to see how plant's reacted.
> The cap I feel,provided a slower release than maybe otherwise.
> If I wanted to experiment with substrate mixes , I might not want to experiment with my fishes for a few weeks/month's.
> Opinion's vary.


Did you actually experience getting ammonia spikes from leached organic matter? If you use soil with a minimal amount of fertiliser - perhaps even mix your own substrate from unfertilised compost (peat, bark fines, coir...) and sand - there's no nitrogen in there to speak of, surely? Rather, the organic component is mostly carbon-based and there to serve as an electron donor for denitrification of ammonia produced by for instance fish. In short, it should be no more harmful to your fish than adding dry leaves for your shrimp to feed on.

I should say this is me theorising from what I know of these processes, not drawing from experience. Hence why I ask about yours!


----------



## roadmaster (Nov 5, 2009)

hivemindhermit said:


> Did you actually experience getting ammonia spikes from leached organic matter? If you use soil with a minimal amount of fertiliser - perhaps even mix your own substrate from unfertilised compost (peat, bark fines, coir...) and sand - there's no nitrogen in there to speak of, surely? Rather, the organic component is mostly carbon-based and there to serve as an electron donor for denitrification of ammonia produced by for instance fish. In short, it should be no more harmful to your fish than adding dry leaves for your shrimp to feed on.
> 
> I should say this is me theorising from what I know of these processes, not drawing from experience. Hence why I ask about yours!


Most soils are by definition, comprised of organic matter.(of some type/source)
Add to this, stuff like worm castings or chicken poop found in some soils like miracle grow organic potting mix, and or urea found in some fertilizer's,and you need some serious plant mass and frequent water changes for first few week's/month's to keep ammonia levels manageable (see suggestions for water changes with ADA soils).


----------



## hivemindhermit (Oct 19, 2017)

roadmaster said:


> Most soils are by definition, comprised of organic matter.(of some type/source)
> Add to this, stuff like worm castings or chicken poop found in some soils like miracle grow organic potting mix, and or urea found in some fertilizer's,and you need some serious plant mass and frequent water changes for first few week's/month's to keep ammonia levels manageable (see suggestions for water changes with ADA soils).


Hmm, I'm a bit confused by your answer. "Organic matter" is an extremely broad term. When applied to soil, it's used to differentiate between the soil's mineral components (in potting mixes this is usually sand, but can also be for instance clay) and the carbon-based compounds that come from decomposing plants and animals. But organic matter is not all alike. Fresh green leaves contain a ton of nitrogen that isn't there in dead, dry leaves, for instance. And soil is made mostly from the kind of compounds that contain very little nitrogen at all. This is why you have to feed your houseplants - they can't grow in peat (or whatever your potting mix is using) alone. Soooo back to my point with all this: If you're using a lightly fertilized soil that's mostly peat or composted bark fines, you aren't really adding much nitrogen to the water.

Also, I really don't think potting soil and ADA soils are comparable in this regard. From what I've read about it, ADA soil is specifically made to release a lot of ammonia. On top of this, I'm not sure about this as I can't find exactly how it's made, but I'd wager it doesn't contain a fraction of the number of microorganisms you'll find in any regular potting soil. Regular soil, as with any organic matter, will contain TONS of bacteria just waiting for some moisture so they can begin multiplying. Which I always thought was the whole point of a dirted tank to begin with: No real need for cycling, because it's already populated.

Which is why I asked if you've actually experienced the ammonia spike you referred to from a cap breach! 

Eh... Sorry about derailing the thread! ^^;


----------



## thedood (May 30, 2015)

Whats the difference between a rotting fish, rotting fish food, or rotting bits of wood? It seems to me the act of breaking down these bits of matter will result in ammonia being produced? To the op original question:



> would the lava rock still be beneficial for the tank if its under the soil?


I cant say for sure. Lava rock is light, some of it will even float until all of the air is removed. It seems to me that it may not stay in place as you expect, the dirt will settle, and may work its way toward the top. If you want to elevate an area and use less dirt use egg crate and build a platform.

One thing I just thought of. The benefit of lava rock would be its porosity. Packing dirt around it would plug those holes up thereby significantly reducing the surface area of the lava rock and thereby reducing the effectiveness. For raising the height of the aquarium floor I think I would look elsewhere. Thats just my opinion.


----------



## hivemindhermit (Oct 19, 2017)

thedood said:


> Whats the difference between a rotting fish, rotting fish food, or rotting bits of wood? It seems to me the act of breaking down these bits of matter will result in ammonia being produced?


Not at all! Wood, bark, peat, dead leaves and so on consist almost entirely of cellulose, which contains no nitrogen whatsoever. And without nitrogen, no ammonia. You only get ammonia once you add something rich in nitrogen, such as fish food - but for that to decompose as quickly as possible, the bacteria need lots of carbon, which they don't have in an inert substrate.

Bump:


thedood said:


> One thing I just thought of. The benefit of lava rock would be its porosity. Packing dirt around it would plug those holes up thereby significantly reducing the surface area of the lava rock and thereby reducing the effectiveness. For raising the height of the aquarium floor I think I would look elsewhere. Thats just my opinion.


I was thinking that the inside of lava rocks (or LECA) would still be empty (or, well, water-filled) which would allow for a bit more gas exchange than without them. Also the grains/pebbles would form stable pores between them, which would make sure that the dirt didn't get completely packed. Like a kind of scaffold, I guess?


----------



## thedood (May 30, 2015)

@hivemindhermit I had never thought about it really, I just figured the same bacteria that breakdown the waste would breakdown the bits of root and what not in the soil and the result would be the excretion of ammonia by the bacteria. So that was interesting.


----------



## AzerNavarro (Oct 27, 2014)

alright so from what I'm getting from all this is that i shouldn't do it haha thank you everyone! maybe ill go return the bag of "lava rocks" i bought from home depot. i will look into using egg crates or maybe even styrofoam. I'm just trying to avoid having to buy another bag of substrate


----------



## shawnwaldon (Dec 5, 2013)

I am using lava rock under my fluval stratum and it is fine. My tank is almost three months old and I never even had an outbreak of algae in the beginning. Now with that said I made the mistake of just mixing it in with some of my sub straight and capped it with more sub straight. In hindsight I would have put it in a mesh bag then capped it with sub straight. A lot of the professionals use it in the manner you want to and it is fine. The only algae I get is just a little on the glass that you can only see if you look from the side of the tank onto the back of the front glass. My water parameters have been very stable the entire time with PH - 6.2, KH - 4, GH - 5. No ammonia, nitrite, and 20 ppm of nitrate. All and all I will include it in all of my tanks. http://blog.greenleafaquariums.com/2011/11/07/gla-substrate-system/


----------



## hivemindhermit (Oct 19, 2017)

thedood said:


> @hivemindhermit I had never thought about it really, I just figured the same bacteria that breakdown the waste would breakdown the bits of root and what not in the soil and the result would be the excretion of ammonia by the bacteria. So that was interesting.


Well, you're not wrong, since the same bacteria need both carbon and nitrogen! If there's no nitrogen source, breakdown of cellulose goes really slowly because the bacteria can't reproduce much. And if there's not enough carbon, breakdown of nitrogen is not as efficient because that's where the bacteria get their energy. Generally to ensure maximum efficiency you want far more carbon than nitrogen - but our tanks tend to contain very little carbon, since we tend to remove dead plants rather than let them decompose, and often use inert substrates like sand or gravel because we think it's "cleaner".

Bump:


shawnwaldon said:


> I am using lava rock under my fluval stratum and it is fine. My tank is almost three months old and I never even had an outbreak of algae in the beginning. Now with that said I made the mistake of just mixing it in with some of my sub straight and capped it with more sub straight. In hindsight I would have put it in a mesh bag then capped it with sub straight. A lot of the professionals use it in the manner you want to and it is fine. The only algae I get is just a little on the glass that you can only see if you look from the side of the tank onto the back of the front glass. My water parameters have been very stable the entire time with PH - 6.2, KH - 4, GH - 5. No ammonia, nitrite, and 20 ppm of nitrate. All and all I will include it in all of my tanks.


I'm assuming when you say "sub straight" you mean substrate, or is sub straight a specific brand..? Anyway - I'm curious, why was it a mistake to mix the lava rock with the substrate?


----------



## roadmaster (Nov 5, 2009)

Is easy to see ammonia being produced from soils alone in glass box of water with test kit and no fishes or fish foods to contribute to the reading.
Agree that the use of the word soil is broad and wildly varying in it's content from both mineral's and organic matter which defines it.
Agree with much of what you shared.


----------



## Gamezawy (Apr 3, 2012)

i have used 2-3MM crushed lava rock as substrate with osmocote and got very good result with plants, and used LAVA rock SPLIT 10MM as you want to use it to fill the place under the main substrate and it worked just fine 

what i wanted to say yes your method will work just fine


----------



## shawnwaldon (Dec 5, 2013)

hivemindhermit said:


> I'm assuming when you say "sub straight" you mean substrate, or is sub straight a specific brand..? Anyway - I'm curious, why was it a mistake to mix the lava rock with the substrate?


I decided to move my tank after the hardscape was set up and it destroyed it. Because I was using both my fluval stratum and sand it mixed them. I had to throw it all out and redo it again because I did not want the lava rock exposed for aesthetic reasons and having sand mixed in didn't look good either. It was about a $100 mistake. Yes I meant substrate stupid auto correct lol and working 40 hours in the last three days so I missed it lol.


----------



## hivemindhermit (Oct 19, 2017)

I'm a little confused why you threw it all out rather than just added a cap of whatever substrate you prefer aesthetically. But to each their own!

Sent from my Pixel using Tapatalk


----------



## AzerNavarro (Oct 27, 2014)

Maybe I’ll just put it in a mesh bag then thanks yall


----------



## Nubster (Aug 9, 2011)

You could also glue it together. The bigger pieces and create the mound then put your substrate over it. That way the underneath structure is not going to move or shift at all. I've used Gorilla Glue to glue lava rock before and it's aquarium safe and works great. Or you can use epoxy or even 100% silicon. Of course a mesh bag will work just fine. But gluing the rock would allow you to get the shape just how you want it. I'm going to use larger pieces to build up a raise area in my new tank and then likely use lava rock "sand" or Eco-Complete or a mix as my substrate.


----------

