Preparing organic potting 'soil' for deep substrated tank

easternlethal

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Dec 26, 2014
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Hi guys - I just purchased some imported organic potting soil to put in my tank (because I live in Hong Kong and haven't found a trusted local supplier). I was expecting it to be topsoil but when I got home, noticed that it was more of the compost variety.

Since I paid quite a lot for it I would still like to use it in my new tank, which is a 50 gallon and will have a deep substrate for aquascaping reasons (i.e. up to 12 inches in some parts). I understand there are two things to worry about: ammonia and methane. So I plan to soak the compost for 1 week and then dry it out to mineralise it. Unfortunately I don't have access to a big enough pot or oven to cook it. But I will also mix it in with ada amazonia (roughly 2 parts of ada to 1 part potting soil) and do a dry start for about a month before adding fish. I will also add rocks in the substrate to help build it up. But since it's an aquascape I will not be using any malaysian trumpet snails either or have any sort of fish that tends to dig.

My question is this enough, given the deep substrate?

Thanks everyone. This is my first post here. :)
 

Whiskey

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Jun 14, 2010
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I've heard of people having problems with such thick potting soil in tanks, the rule I always went by was an inch or two of potting soil capped with an inch or so of 2-4mm gravel. The cap is important because it keeps the potting soil down.


How about building the slope underneath using rocks or something so even on the slope the potting soil will only be an inch thick? I'm not sure if this will work having never tried it, but I think it might be better than 12 inches of soil.


Just an idea,


Whiskey
 

easternlethal

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Yes thanks Whiskey I will try to do that, although I tend to move things around quite a lot especially whilst it's establishing so it's sometimes hard to tell where the soil will end up in certain spots..
 

Whiskey

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If you plant to uproot allot then the ADA soil alone might be a better option for you, the trouble with the potting soil is that when you pull plants out it comes from under the cap and floats around all over the place. It is typically used in tanks which are low tech and don't have lots of plant moving around.


Whiskey
 

easternlethal

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That's a good point. I read Walstad's post somewhere that she tried cutting off a plant stem and leaving the roots in instead of removing the whole plant. At the time it caused problems for her because the roots started rotting and I wondered why she did that at the time. Now I think I know why...


I'm also not too keen on gravel caps because I think they are difficult for carpet plants to grow. I've tried doing a dry start with potting soil and a very thin layer of sand and even then my plants found it difficult to take root in places.


If i had my way i would really like to bury it deep in the aquasoil at the bottom of the tank. I know there's a risk of gassing but I've been soaking it the soil in water for over a week already and plan to establish the tank for a month before adding fish... hmm...
 

Joshua Caldwell

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Apr 21, 2015
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I would suggest building up the hill with plain gravel, then coat with an inch of dirt then do your top layer on that.
 

easternlethal

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About a year later and my substrate mix seems to be working well. The only thing about the dirt is that it can generate a powdery mess when I uproot plants which gets swept into my filter. Along with the natural settlement of the substrate, it looks as though my soil is naturally eroding so I am thinking of topping it up with more aquasoil.