Potting soil as substrate? Can it be done? - The Planted Tank Forum
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post #1 of 7 (permalink) Old 08-08-2007, 04:50 PM Thread Starter
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Potting soil as substrate? Can it be done?

I did a quick search (very quick) and didn't see a whole lot about it. I could have been missing some posts, but I'm sure you guys don't mind answering the same question 50x. Hey, I have to do it on the car audio board I moderate!

anyway, I was wondering if I could use the every day black potting soil that can be had cheap at walmart or other places like that. I have Florite and sand in one of my tanks, but want to do something different in my nano. I don't want to drop $25 on a bag of EcoComplete if I can do it for $3. The tank does have a betta in it that I would very much like to keep alive, so I'm asking before I act in hopes that someone tried this out already.

thanks guys!
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post #2 of 7 (permalink) Old 08-08-2007, 05:12 PM
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I use top soil, not potting soil, under a gravel or sand cap. Potting soil usually contains fertilizers and amendments that will make a mess of an aquarium. I usually tell people not to try the soil as a first attempt at a planted tank, but since it is just a nano, go for it.


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post #3 of 7 (permalink) Old 08-08-2007, 08:31 PM
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but I'm sure you guys don't mind answering the same question 50x. Hey, I have to do it on the car audio board I moderate!
No kidding! But I don't mind.

I've been reading up on this as well and have been playing with it by putting some different soils in pots, planting the plants in those and putting them in a tank. I also have some experience from using different soils to pot plants in goldfish ponds. Here's what I've learned...

Most types of potting soil have lightweight things like bark and perlite (those little styrofoam-looking balls) to help keep the pots of plants from being too heavy to move and the soil too heavy for water to penetrate. Those lightweight things also make potting soil unsuitable for a planted tank. You can put sand on top of it to hold that stuff down, but the first time you pull up a plant, up comes loads of floaties.

Some bagged soils sold as potting soil are more akin to plain old topsoil, but still not quite there. These don't have bark, perlite, vermiculite, etc. ~ they're just sandy loam with added compost. But it's the compost that can cause problems in a planted tank. Compost is decomposing organic matter and you know what that causes in a planted tank ~ ammonia spike. That's what happened in my tank from just a couple pint-sized pots of it in there. And when I pulled them out to repot the plants, talk about stinky!! Anaerobic heaven it was!

Just plain topsoil, like Sean advised, would be the one to use. No added compost, no added fertilizer, no added anything. Read the bag to make sure and open it if you have to to make sure there's no bark and things like that in there.

BTW, you might check out the low tech forum, too. I think I've seen a lot of posts about using "dirt" as a substrate over there.

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post #4 of 7 (permalink) Old 08-08-2007, 08:57 PM
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here's more info.
stay away from extra ferts & uncomposted materials like bark & wood chips.
Compost is fine. It'll act like peat moss.
ps. peat moss is fine too.

and I would recommend it for a small tank, first timer. I leave my 5G natural tank by a window (south) and that's it. No lights, CO2, or ferts.

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post #5 of 7 (permalink) Old 08-08-2007, 11:32 PM
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We do a lot of research on muck and wetland soils.

I have to honor of processing and washing 1000's of lbs of delta sediments for use for my research, oh the glamour

I've got plenty and have been playing with it in a number of different systems to get a good feel. We send it off to get it analyzed etc.

It's great and will grow any plant well without any water column fertilization.
I rinse it well with a hose and screen it through a window type size screen.

I place this over a wheel barrow. Then the fines settle and the murky stuff decants over the edge.

I let that settle for 1-2 days and consolidate.

Then carefully decant.

Then I let it dry and dewater some till it's a nice pasty clay.

The washing helps oxidize the NH4, which is the problems with new soil tanks.

Now you can boil the soil for 10 minutes to do this, bake it for an hour or so, this will oxidize thermally the NH4 to NO3.

Or do the bio method,: soak for 3 weeks in shallow tray to oxidize the NH4 via bacteria.

All work well.

You can mix the soil with 1:3 parts soil : sand and then make a nice 2" layer or so of that deep and top with another 1-2" of 2-3 mm sand, SMS etc.

I've found some growth difference between ADA aqua soil vs delta sediments, with more growth with the delta sediments over an 8 week growth study using 3 aquatic weeds.

I also used Top soil(no pre soak and pre soak).
The no pre soak had blackened anaerobic roots, some on the pre soak.
None on the ADA and none on the delta soil.

The system was flow through so interactions between the water column and leeching can occur.

So only the sediment is the source of nutrients, totally lean water column via a large DI unit and stable ambient low CO2.

Good stuff to use.
the removal of NH4 resolves 90% of the issues folks have with soil and some other care and tricks resolve the potential mess. So do not move plants around a bunch for awhile.

Tom Barr

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post #6 of 7 (permalink) Old 08-09-2007, 08:28 PM Thread Starter
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thanks for the replies guys, and the heavy info, Tom! I may just end up buying some Eco Complete, but I'll take all this into consideration when I decide what to do.
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post #7 of 7 (permalink) Old 08-11-2007, 06:35 PM
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I have used top soil in lots of tanks and not had a problem (yet)
I have also used john innes no2 in fact this was the substrate we used for all planted tanks while at college.
I tested (not as scientifically as Tom has) while at college several different substrates against soil at college and found that the soil nearly always showed better results

I usually use a layer of soil followed either by just sand if thats the desired substrate or a 1cm layer of sand and then a top substrate of whatever gravel you would like.

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