Dirt Sub-Substrate

[Crazybob]

Hey all,
 
After 8 glorious years my oscar has died (he will be given a viking funeral) and I am going to be moving my fish from my 40 gallon tank to the 75 gallon. My current plan is to put down a layer (1/2 - 1") of dirt and another 1/2 - 2" of playsand on top of it. Currently in the 40 gal I am only using play sand with mixed results of plant survival. Currently I have a few amazon swords, anubias, and some java ferns.
 
If I proceed down this path am I going to need a heavily planted tank or will having a few plants still work? I don't particularly want to have to deal with providing fertilizer for the plants with the innert sand but I also don't want to be fighting algae by having the dirt down.
 
Any advice would be appreciated. Thanks for the help.
 
Tank Set up as follows:
 
75 gallon tank
Filtration: marineland C360 canister filter
Lighting: Current USA Satellite Freshwater LED Plus

 

 

[RRaquariums]

I used dirt for a long time in my smaller tanks and then in my larger tanks. If you do go with dirt don't use sand on top as it traps gass that will build up from the dirt breaking down. You need a fine gravel bed on top to hold down the dirt by allow gass exchange. Another problem with the dirt was any time you want to add a new plant or move an old one you will make a huge mess pulling it out of the dirt and once that dirt is released into the aquarium to free float then you can have algae blooms.
So while a dirt tank can work it dose have its downsides. I'd consider just having a sand bed and using fertilizers instead of dirt in the long run its a lot less of a pain.

 

[Byron]

I will begin by saying that I have never used soil, and likely never will, but I have researched the topic quite extensively before reaching my decision.  As Matt mentioned, there are serious issues with soil.
 
Given your list of plants, you would not see much if any benefit over plain sand or fine gravel.  Anubias and Java Fern will gain nothing.  My tanks are full of sword plants and have been for over 25 years.  You may need to add a comprehensive liquid fertilizer, and substrate tabs will benefit the larger sword species.
 
Aquatic plants remove all their nutrients from the water, via roots and leaves.  Some nutrients are only taken up primarily via leaves.  And any fertilizer added to the water will make its way to the substrate naturally.  But having said that, providing some nutrients in the substrate does help plants like the large Echinodorus species.  However, soil is somewhat misunderstood in this regard.
 
The benefit of soil is the organic content.  Primarily, the release of CO2 from the decomposing organics.  However, this also releases ammonia, and it is possible during the first six months to have ammonia levels high enough to harm the fish.  Even Diana Walstad, who basically got aquarists thinking of soil substrates, mentions in her articles and book that any sand or fine gravel substrate will be equal in benefit to soil after a year, if it is left alone, and at the same time a soil substrate loses its benefits in roughly the same time.  Beyond this, nutrients need to be added to replenish the soil.
 
Obviously one can use soil, if one understands the issues, but at ther same time it is not necessary, so I would think this through carefully.  I mentioned my swords, so I will just add a couple photos of the present tanks to illustrate their condition.  These tanks have play sand only as a substrate, and I dose liquid fertilizers weekly in both these tanks. I have one Flourish Tab next to each of the larger swords in the second tank, replaced every three months, but none in the first tank.
 
Byron.

 

[RobRocksFishTank]

Nice tanks, Byron. Love the hatchets.
 
Some good advice there, too, as I was wondering how plants would do in sand. As to the sand being good after a year, if you don't do anything to it. Can it be good sooner than that by adding ferts or is it best to wait?

 

[Crazybob]

Gorgeous tanks! Thanks for the advice all I think I will just use my sand when moving over. I believe I still have powders from days when I dabbled in the ei method so I will try to drum those up. Is 1-2 inches an appropriate amount of sand?

Byron,
do you add co2 to Your tanks or just light and ferts? Also, if I may, what are the smaller plants in the tanks?

Thanks for the advice again!

 

[Byron]

I can answer both posts (#4 & #5) with one response as they are related.
 
I have never added any type of carbon, either diffused CO2 or the so-called liquid chemical, as I rely completely on the natural CO2.  Most of this comes from the decomposition of organics by bacteria in the substrate, with some (less) from respiration of fish, plants and bacteria themselves.  But the main source of CO2 is the substrate, and this is the idea behind the year.  It takes a period of time for sufficient organics to build up in the substrate, along with the various bacteria (aerobic and anaerobic).  Diana says about a year, but I suspect it is much sooner.  Soil has the organics in it, so this CO2 release begins immediately, which is the benefit (but keeping in mind the ammonia issue).  I generally leave the substrate alone, never digging or poking into it; this varies a bit, depending upon the tank and fish.  I have had cyanobacteria issues in my 70g, and cyano is due solely to organics, so since I started doing a surface clean of the sand during water changes, this cleared up.  But I never see this issue in the other six tanks.
 
I aim for somewhere between 1.5 inches and 2 or 3 inches depth, overall (= evenly spread over the bottom of the tank), depending upon the tank size and thus the probable size of rooted plants.  In the first photo tank, a 29g, I have about an inch.  I intended to have basically a plant-less tank (except for floating plants) with primarily branches, so I didn't use much sand.  I stuck in a couple of chain swords, Helanthium bolivianum, and in the seven months since they have spread everywhere as you can see.  The larger Echinodorus griesbachii was an adventitious plant from the second tank that I didn't want to toss out so I stuck it in the 29g last September and left it alone.  The second photo tank is a 115g, and has been set up for close to four years now; I changed from fine gravel to play sand in August 2011.  I am regularly culling out runners from the chain swords, also H. bolivianum in this tank; this is the "larger" chain sword species, and the smaller is H. tenellum and I have this one in my 70g and 10g.
 
The other nutrients apart from carbon will occur from fish food and water changes.  Depending upon local water and the fish load, this may be sufficient, but I have very soft water so I need to be adding all of these from day one.  I use a liquid complete supplement (Seachem's Flourish Comprehensive Supplement happens to be what I use) once or sometimes twice a week.  I am also using Flourish Trace and found I was able to reduce the Comprehensive to once a week instead of twice, and this helped with algae.  The Flourish Tabs are added next to the larger swords but not in the other tanks.  The three largest tanks also have Equilibrium added after the water change to raise the GH from zero to around 5 or 6 dGH; this is needed in order to provide sufficient hard minerals, especially calcium and magnesium, or the larger swords begin to deteriorate.  In the other tanks with the smaller swords and other plants, this hasn't been necessary so they stay at zero GH and KH.
 
I'll attach a photo of the 70g for reference as it may be of interest.  This is also play sand, but I should probably have used more (there is about 2 inches overall depth) but now after two years it seems OK.
 
Byron.

 

[Crazybob]

Thanks for your advice Byron.
 
I ended up going with an all sand substrate and set up the tank over the weekend. There are only 2 java fern, and a very small amazon sword in the tank right now. Going to try to go to the store tonight and pick up a few more as the tank is looking a bit barren (see attached, just after move). I have dry ferts from a while ago when I attempted (with mixed results) to do the EI method on one of my tanks. If i mix this in a solution per the EI Method thread would this roughly equate to the Seachem flourish liquid? My thoughts would be to dose a few ml per week as I do not want to get high tech with it (see first post for tank specs).
 
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[Byron]

I have never used EI method, as here again it sounds too risky [more below].  But aside from that, I would be careful in a new tank with EI as you are more likely to have algae issues with the unstable biological system in new tanks, and nutrients have to be carefully controlled.
 
With those fish, some largish chunks of dark wood would be ideal; Malaysian Driftwood is what I use.  And yes, more plants as you find them, and include some good floating plants.
 
On the EI, the problem is that one is dumping in an excess of some nutrients (this is deliberate, according to Tom Barr).  Aquatic plants have a requirement for 17 nutrients, but these should be in specific proportions to each other.  If there is too much of one, the plants will sometimes shut down assimilation of another.  This is why I like the prepared liquid fertilizers, they are proportional according to the plants' needs, so it is easier first to ensure everything is getting in, and second to keep things balanced.  This is my thinking, which I accept not everyone shares.
 
Byron.

 

[Crazybob]

Thanks for all of your help Byron,
 
I was mostly hoping that the EI powders could be mixed to the Flourish formula, I don't plan on using the EI method. I will pick up some flourish tonight perhaps. I will look for some more and larger driftwood tonight as well with my plants. Thanks again.

 

[Byron]

Thanks for all of your help Byron,
 
I was mostly hoping that the EI powders could be mixed to the Flourish formula, I don't plan on using the EI method. I will pick up some flourish tonight perhaps. I will look for some more and larger driftwood tonight as well with my plants. Thanks again.

 
You're welcome.
 
I don't want to mislead, so I'll just say that lots of aquarists use the dry fertilizers with no issues, so that is fine.  But you have to be careful especially during the initial stages as I explained.
 
Byron.

 

[jag51186]

I just wanted to say that the barren-ness of the tank compliments the skull nicely lol. Looks like a desert, which makes an interestingly ironic statement given that it is underwater.

 

[Bugdozer]

I've had a soil layer at the bottom of my tank; all my rooted plants except one have died (and that one is now fairly ropey) while my non-rooted plants have gone from strength to strength. When I next set up a tank I'm not going to bother with soil.

 

[Alasse]

I use unwashed propagating sand under my capping sand....grows plants like a weed
 
to give an idea on speed of growth....12 days between photos
 
13th April

 
25th April

 
This tank get liquid carbon daily (definitely makes a difference with plant growth), and also twice a week the tank is dosed with a fert