What to look for/avoid in Potting Soil substrate?

[Twimbo]

I have started an experimental 20g tank using potting soil capped with 3/4 inch of gravel. I simply purchased an organic potting soil from Menards (our local building supply warehouse). Its about two weeks old and both the plants and fish (guppies) seem to be doing well.

I've heard folks say to avoid potting soil with fertilizers or perlite. I'm curious about what those of you who are using potting soil in your tanks either look for or avoid in a commercial brand of potting soil?

The soil I'm using now lists the following ingrediants:

• Canadian Sphagnum Peat Moss
• Organic Materials (reed -sage, peat, or composted forest products)
• Horticultural perlite
• Organic Wetting Agent
• Lime (for proper Ph control)

I know the perlite bothers some folks. I find it a bit extra work to clean up, but otherwise workable. A old thread in this forum suggests it does not pose health risks for fish or plants.

I am a little concerned about the Lime (which I just noticed now, as typing the ingredient list). Will that be a problem?

[lauraleellbp]

You need to keep an eye on your water parameters. Especially as many potting soils contain urea. Keep a close eye out for ammonia spikes, or any other fluctuations as the organics start to break down. Be sure to do large water changes any time you do any major work in the tank, as disturbing that substrate could bring on an ammonia spike for a long time to come.

[bradac56]

I agree with lauraleellbp plus that 'Organic Wetting Agent' is going to cause pH spikes.

I'm not sure on the lime I'll have to look into that or Mr. Barr would probably know right off.

- Brad

[lauraleellbp]

Originally Posted by bradac56

'Organic Wetting Agent'
- Brad

I know the first thing that popped into my head seeing that, not knowing what it may really be... ROFL

[bradac56]

That's the little blue or white balls they put in terrestrial potting soils to help plants hold moisture works really well for flowers but does crazy things like spike pH in aquariums. The best example is regular Miracle Gro.

- Brad

[Twimbo]

I've seen a number of people post comments like this one found in another thread:

Originally Posted by bradac56

but make sure the top soil is a non-fertilized brand. You'll need to go to a orchard or lawn-care supply store instead of a big box store to get it but the upside is it will cost less.

Does the potting soil I described at the start of this thread qualify as a non-fertilized brand, I bought it at a big box store?

Is there anything else, like possibly lime, that I might want to avoid in the potting soil I use in my planted tank?

FYI - The brand I purchased is "All Purpose Potting Mix, Natural Organic" by Schultz.

[Twimbo]

I found this article that explains what "soil wetting agents" are, in general. It does not address this specific case.

[bradac56]

No Menards/Lowes/Home Depot/Wal-Mart/Sam's Club does not carry a not-fertilized topsoil all of there stuff is for terrestrial gardening. The brand really doesn't matter just that it says "no fertilizers' on the bag if it doesn't say that then it does have ferts, and is made from 90% pine bark.

- Brad

[lauraleellbp]

Originally Posted by Twimbo

I found this article that explains what "soil wetting agents" are, in general. It does not address this specific case.

Can't say I fully understand all the chemistry, but I'd be leery of introducing surfactants into an aquarium.

[henkychif]

Isn't peat moss to be avoided as well? I believe I've read that somewhere. I was lucky enough to have found organic potting soil from a local farm that had a high clay content and nothing added, but it was very hard to find. Only one store carried it and it was not a big box store like home depot.

[bradac56]

Sure peat moss from a big box store for terrestrial plants should be avoded as they tend to have ferts in them but sphagnum peat moss has been used in aquariums for ever with good results on lowering/controlling pH.

It's worth the time to check out all of your local landscaping/orchard supply stores verses big box stores you'll find allot of usefully stuff.

[SCMurphy]

You didn't buy potting soil, you bought potting mix. I use potting mix to grow tomatoes and peppers in self watering containers on my deck. The manufacturer tells you to use the potting mix because real soil would compact and prevent the plants from rooting well in the boxes. I haven't tried using the mix in an aquarium, keep us posted with your results.

[Twimbo]

I just found this description by Diana Walstad, of the potting soil used in one of her aquariums. Other than the "Organic Wetting Agent," it does not look that different from what I used.

"For substrateFor substrate, I layered the tank bottom (1 ft X 4 ft) with 1 inch (16 lb) of potting soil recommended for growing houseplants. It contains organic compost from mushrooms and forest peat fiber, sand/bark fines, vermiculite clay, perlite, and dolomitic limistone., I layered the tank bottom (1 ft X 4 ft) with 1 inch (16 lb) of potting soil recommended for growing houseplants. It contains organic compost from mushrooms and forest peat fiber, sand/bark fines, vermiculite clay, perlite, and dolomitic limistone."

FYI - I finally got around to setting up a tank journal for my "Potting Mix" tank. So far, no problems in this tank. I'm keeping my fingers crossed!