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Discussion Starter · #1 ·
I've been looking into starting a dirt tank, and I'm wondering why you have to 'cap' it with sand or gravel? Also curious about using mud instead of topsoil . . .

Any advice or information on this would be greatly appreciated! I still have a lot of research to do here! :-D
 

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Jes all I am saying is YOU need to do one as you have the tanks for it and I know you have the time for such a project! LMAO!
 

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Discussion Starter · #3 · (Edited)
Yeah, you're a reeeaaaaaal funny guy, John ;) I WILL have *some* time. . . after I shut down, like, four tanks or so. . . since I'm already considering setting up a breeding tank for my rams, might as well make it 2 in 1, neh? Or... maybe not. Rams LIKE sand. But I DO have a plant only QT tank. . .hrm

I'm really wanting to try a dirt tank. . . eventually the plan is to move Becoming into a 125 or so, and though that's some time down the road, you know what a planner I am! I'm considering substrates, and am very interested in the concept of dirt or mud. . . but I think this is something that I'll really need to try out in a smaller tank before committing to something so huge!

Even if it's not the best plan for the bigger tank, I'd like to give it a try, anyway. So I know. . .I just don't understand why the caps? I think a plain ol' dirt or mud bottom would look nice - but nobody does it? Why!?
 

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I'm not suuuper familiar with dirt tanks, but from my experiments with bottles/containers, the cap is necessary to stop the light particles of the soil from floating all over the place and making the water black and icky. When you cap it, it prevents the soil from just floating all over the tank. And it being soil, it's kind of impossible to 'rinse' the fine particles out. I've 'capped' with both sand and gravel. It almost acts as a filter, when you fill the container. It traps all of the particles beneath it.

Another thing I can think of off the top of my head is that dirt tanks require a lot of time to stabilize and be safe for fish. Something about the soil producing a lot of ammonia/CO2.

What do you mean by mud? I'm always tossing around the idea of using sand from the lake in a biotope aquarium, but there is so much other gunk and creepy eepy crawlies in there that I'm a bit terrified of doing so, lmao.
 

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Discussion Starter · #5 · (Edited)
Thanks Jen! I suspected that floaty bits would have something to do with it - but wouldn't these particles eventually be filtered out?

As far as ammonia/Co2 - like you said, it takes time to stabilize - regardless of a 'cap.' So. . . that *shouldn't* apply, right? Or not. . . *shrugs*

I mean mud, lol! Yeah. . . creepy crawlies. . . but if the mud were, I dunno, boiled and baked before putting it into the tank, wouldn't it be okay eventually? *scratches head*

I'm about to re-read my D.Walstad and P.Hiscock books, maybe I missed some info in there the last time around - I was just reading to learn, not intending to actually set one up at that time. I'm in no rush to add stock, so time isn't a factor. I just want to understand before I get started.
 

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Discussion Starter · #6 ·
Been looking through threads on other plant-related forums. . . it is done, and done well, from what I've read so far. I may have to give this method a try on one of my soon-to-be empty 10g tanks and see how it goes. I can start with a plant-only tank while things are settling, and if all goes well lightly stock after some time has passed. Still have a LOT of research to do.

Any input welcome!
 

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I pmed you, but.. a sand or gravel cap only speeds up the process that would happen naturally: nearly all soil contains sand or gravel, and over time clay sinks and most of the silt washes away, which leaves a clay-rich capped substrate...
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Discussion Starter · #8 · (Edited)
I pmed you, but.. a sand or gravel cap only speeds up the process that would happen naturally: nearly all soil contains sand or gravel, and over time clay sinks and most of the silt washes away, which leaves a clay-rich capped substrate...
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Thanks for your input, and your PM, Redchigh. I really appreciate your input here, as I know you're one of our resident experts when it comes to dirty tanks!

Interesting point you bring up about the natural process of things. . . and I agree that their is separation that happens, but the rivers and streams around here don't so much have 'sand' It may be a coarser grain of something or another though. I'll have to pay more attention the next time I take a journey out!

Either way, would there be any issues with letting this process happen on it's own, and not capping it to begin with? If I mineralise the soil heavily, as you recommended (and as I'd be inclined to do, anyway) and then sifted it, would the tank still be a dirt-covered mess for a very long time? Or is it something that would more or less settle fairly quickly? You did say in your PM that it could take months to clear without a cap, but is there any way around this? I saw a 'test' somewhere along the line of my reading the other night where you shake some soil in a jar and mark the levels of settling at 1 hour 2 hours, overnight, etc. During the process of mineralization, wouldn't a LOT of the silt get washed away, leaving the heavier, but smaller, bits that WOULD settle more quickly?

I can be patient, this is more about experimenting and seeing what happens than actually having any particular goal in mind. . . though I would like to NOT end up with an algae-covered muddy water tank if at all possible, lol!

From what I'm seeing on other forums, mixing the soil with clay helps in the settling process. I believe most people say 10%? You mentioned in your PM that you'd recommend that I mix the soil 50 - 50 with sand. What if I didn't? Could I actually JUST use the soil and have it work out? Or do the plant roots need that heavier sand to hold them down and into the substrate?

So much left to learn - thanks for lending the benefit of your experience!
 

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its surely not "play sand", but its a particulate of stone and minerals... essentially, sand. ;)

If its slow moving, the water will likely have more silt, but be less clear.

If you want it to be all natural, you could seperate your soil in order to have the layers form faster... Clay makes the substrate heavier, and inhibits water flow throw the substrate, which 1, keeps the water clearer (as long as its not stirred up), and 2, encourages anaerobic bacteria and the possibly lethal buildup of hydrogen sulfide and co2 bubbles. (bubbles of harmless co2 can also stir the substrate when it burps, causing cloudiness....)

during the settling process, use a powerful filter (that wont disturb the substrate) along with an airstone. After a week or two, remove the airstone, test the params and if they're good, add fish.

You want some clay in the soil, but most soil has clay in it.

After all, worst case scenario is drain the tank, cap with sand, and refill.
 

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Discussion Starter · #10 ·
its surely not "play sand", but its a particulate of stone and minerals... essentially, sand. ;)
Heehee, I getcha - and that is exactly what I want! So then. . . over time, the soil will cap itself, and in theory, keep it from being a mess forever. . . will the silt eventually settle/filter out?

Clay makes the substrate heavier, and inhibits water flow throw the substrate, which 1, keeps the water clearer (as long as its not stirred up), and 2, encourages anaerobic bacteria and the possibly lethal buildup of hydrogen sulfide and co2 bubbles.
You just made using clay sound really scary . . . the clearer water part, I'm down with! The possibly lethal buildup. . .not so much! With my sand tank,s I have my little MTS happily digging away in order to prevent these things from happening, and in the few areas where I have no plant roots to help me, I sift the sand every few months to keep any anaerobic pockets from forming. . . I suppose I won't be able to sift the soil without causing a ruckus - is this something that I should be worried about over time? Can MTS help here? Hmmmmmm... don't want to kill anyone, though I'm sure I'll be waiting longer than a week or two before adding any fish - just to be sure!

You want some clay in the soil, but most soil has clay in it.
If most soil has clay in it. . . should I add more or not? In most of the personal accounts I've seen, people are adding 5 - 10% of a natural clay to the soil before putting it into the tank. I'd probably mix everything in and watch it settle into layers naturally - that's something that I'd enjoy. . .

After all, worst case scenario is drain the tank, cap with sand, and refill.
*nods* No harm, no foul, eh? This is going to be fun. . . I'm going to re-read some of my planting books, especially Walstad, re-read YOUR guide, and find as many tank logs as I can, so that I can get a bit of a better concept behind exactly what will be going on during this process. . . thank you for all of your help!!! I'm sure I'll have many more questions before I'm ready to go!
 

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I would definitely suggest having a cap. Also, I would recommend moving/adding plants as little as possible. I had a sand cap and even after 1.5 years, the soil was still making its way into the water column. The sand eventually just mixed in with the soil and became useless. I had to adjust my powerhead to limit the flow at the substrate because it would turn the entire tank into a muddy mess. All it took was a fish flaring or swimming fast towards the bottom and dirt was everywhere. I can't even imagine how bad it would have been if I didn't use any cap at all. And redchigh is right about the H2S buildup in the soil; occasionally when replanting trimmed plants I would pop open an air pocket in the soil and a large H2S bubble would rush to the surface. I personally don't expect to ever go back to a soil substrate; sure t was cheap, plant growth was incredible and I didn't have to start dosing ferts for like six months or so, but it was just too much of a hassles and I hated never having a clear tank. That's just my opinion though.
 

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Discussion Starter · #12 ·
Thanks for the input, Funkman!

I've read a LOT of personal accounts that ended on same note as yours . . . a dirt tank was too much trouble all around than really necessary - which makes sense to me. . . it seems that the potential for disaster with this type of substrate - either with just plain muddy water or hostile algae takeover - is fairly high with this method.

For now, this is going to be STRICTLY experimental, I'm hoping that I have better luck than some of the accounts I've seen, but if things don't work out, I won't be out much money, and can chalk it down to a lesson learned, or try again with a cap.

I don't have any fish that need a home right now, and if that changes, I have other tanks that I can set up in a way that I'm more familiar with, plus my QT tank is up and running in case of emergency. . . so this is really just for fun and learning. . .

Fingers crossed that all goes well! I still have a lot of reading to do before I get started just yet. . .

What type of soil did you use when you ran your tank?
 

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I don't really recall, but I think it was miracle grow potting soil or something. I apologize if I came off as if I'm trying to convince you to not do soil at all, it's just that it's not the right substrate for me since I tend to move plants around a lot. With this method you really want to just set it up and leave it alone. I'm sure having no cap at all is possible, but the problem is you're really going to want to limit the amount of flow in the tank to prevent blasting the soil all around (and believe me when I say it doesn't take much for that to happen) which already presents a problems because the plants may suffer in stagnant water. Another problem with no cap is that it's really difficult to keep the plants buried. It may depend on the soil chosen but after my cap dropped towards the bottom of the soil, it wasn't really dense enough to keep trimmed stems down. Plants with roots already established weren't as bad though. Again, I'm not trying to discourage you; Walstad tanks are awesome, but I just wanted to make sure you understand what you're getting yourself into :thumbsup:
 

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Discussion Starter · #14 ·
Not at all, m'dear - I REALLY appreciate your point of view!

The soil alone not being heavy enough to weigh down the plants is one of my concerns... maybe adding clay will help there? Or mixing sand in and seeing if it caps itself. I'd really still like to try all dirt and see how it goes. I know it isn't the norm, and it seems that the reasons for this are fairly obvious! Still. . . I'll give it a whirl!

Though I am seeing two very different perspectives between you and Red - he is of the impression that the sand would naturally end up on the top and cap itself, where you're saying that in your tanks, the sand sunk down and into the soil. . . interesting. . .

A few users here, and a lot of reading on other threads has me pointed in the direction of Miracle Grow ORGANIC potting soil mix, not sure I've ever seen it IRL, but I'll have to check out the garden centers in the bigger shops. Hopefully I'll find it. Still curious as to if I could use just. . . regular soil that I dug up from the forest or something, lol! I suppose that the chances are WAY higher for contaminates in that stuff. . .lol!
 

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I agree whither his observation, there is just missing information.

I use dirt, which is relatively low in organic matter, heavy, and has really tiny particles.

Funkman likely used a potting mix or garden soil (which one of my old guides reccomends, and even Diane walstad reccomends it). Unfortunately these peat and bark-based mixes have large chunks and are very lightweight (which causes them to rise) and in being lightweight, they are airy, which encourages hydrogen sulfide pockets.

The top inch or so of substrate will be aerobic. The rest (except around plant roots) will be anaerobic, which is normal. The anaerobic areas break down nutrients, convert nitrate to nitrogen gas, and other beneficial things. Anaerobic bacteria is the main reason soil has benefits.
Just make sure the aerobic layer is healthy and the whole substrate is gritty enough that water can flow between the layers. The aerobic bacteria breaks down hydrogen sulfide, and converts it to H20 and co2. (I think the sulfur, which is a nutrient, remains in the substrate to continue the anaerobic cycle.
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I've had good luck with soil tanks, being pretty rock stable when I used soil I dug up myself. They often saw shrimp or fish the same day as setup and never had a problem. My most recent soil tank I setup in winter so I was forced to use a store bought bag of topsoil, which has proven to be quite the hassle in comparison. It actually killed off the few initial plants I stuck in there. It is slowly coming around and has growing plants as well as fish now, but its been quite a hassle in comparison to my other soil tanks.
 

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I have used Miracle Grow Organic Choice Potting mix with no problems. The tank ran for 6months with the mix and a sand cap. I no issues of soil or particulars floating around. Though moving plants is a hassle it can be done if done right. Its not really recommend though as Funkman stated. I had fish in the tank 10 days later after the setup. Never had any ammonia issues. I would use it again though am curious about a soil tank without a cap is some kind.
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I shoveled dirt into an old tshirt (tied up the sleeves) and washed it through the shirt really well, then soaked it a couple days, washed it again, soaked it etc several times and ended up with a really clean sandy soil with a few roots and tiny twigs... Thinking back, it would have probably made a nice natural cap for soil....
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Discussion Starter · #20 ·
Thank you all for your input and experiences!

Mika - I was planning to pop on chat and pick your brain for info, lol! I know you've used dug-from-the- woods soil before. . . I've alwasy told you that I'd be entirely too much of a fraidy cat to do things that way, but that the idea appeals to me . . . I think I might finally be ready to go that route. How much more natural can you get?! Did/do you use a cap on your dirt tanks? (HEY! Am I missing updates to that last tank? I haven't gotten any notices from you!)

Nice t-shirt idea, Red, lol! I might have to give that a try! You're right in that almost everyone uses/recommends the topsoil. . . though most of the things I've read do recommend that you sift it through some type of screening first, it makes sense that it'd be lighter, just because it is.

Just make sure the aerobic layer is healthy and the whole substrate is gritty enough that water can flow between the layers.
RIGHT up until you say stuff like this, then I get nervous again! Having never done this before, how do I know that the substrate is gritty enough to be healthy, and that the water is able to flow through? I'm not planning to actually layer it (I don't think). I suppose this is one of the areas where adding sand into the mix - even to separate naturally, and not as a cap - comes into play?

One last question . . . is there anything that I should do extra, aside from the mineralization process, to make sure that 'wild-caught' dirt is. . . clear of anything that would hurt the critters that may or may not eventually be living in the tank? Weird question, but should I bake it or boil it, lol?! To those that have used the stuff before, is it best to get it from an area that is farther away from water or actually in or near the water - or would it not matter? And what am I looking for in a good dirt?

John. . .we're both curious, and hopefully soon to find out, lol!

HAHA! So many really weird questions that I never thought I'd ask!!! Thank you guys for being patient and lending your experience! I appreciate it!
 
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