Choosing the right soil substrate

[rivulet]

Getting into live plants has me revamping my 10-gallon tank, currently just gravel as the substrate.
The plan is to have snails in there, maybe a couple neptunes later on, once it's fully cycled.
I've come across the idea of using organic potting mix as a nutrient layer at the bottom, but what about regular potting mix?
The fertilizer it contains - does that pose a risk to my livestock? I'd only be using a thin layer, but I'm still concerned.
Also, I've read that the wetting agents in these mixes can be problematic.

I'd love some insight on this.

[luminx]

I've been looking into this too, and from what I've found, organic potting soil can indeed leach ammonia, so it's usually a good idea to cap it with a layer of sand or gravel. I've seen people use about an inch to an inch and a half of the organic soil, and then a slightly thicker layer on top to prevent any issues.

[coltin]

I'm not a fan of using soil in aquariums, to be honest. It's more hassle than it's worth, and you'll likely end up replacing it within a couple of years due to anaerobic conditions. And let's not forget the ammonia issues that can plague your tank for months after adding soil.

If you're dead set on adding some extra nutrients, I'd recommend using red or orange terrac instead. Make small balls, around 10mm in diameter, and push them into the gravel under your plants. That's it - no need to overcomplicate things. Then, just add a liquid iron-based aquarium plant fertilizer to the water and you're good to go.

[rivulet]

I'm looking for the best option to provide nutrients for my live plants, while planning to cap with sand or gravel. What's a suitable substrate to use as a nutrient layer underneath?

[desertstream]

I've tried the soil route for a "dirted" tank and learned a thing or two. First off, steer clear of anything with wetting agents - they're a no-go. Look for an organic soil and sift out as much of the chunky stuff as you can. I'd avoid soils with poop in them, trust me, it's just asking for trouble. Some folks bake their soil in the oven, but I just leave it out in the sun for a bit - seems to do the trick.

Before adding the soil, throw down some lava rock - the kind you'd use for a BBQ. It's inert, so it won't mess with your water, but it'll give your soil some room to breathe. Then, sift that soil into the tank and make sure it's nice and wet, like a thick mud. Cap it off with about two inches of sand or gravel. The nutrients will leach into the water, but it's not fish-friendly for a couple months. And let's be real, in two years you'll be ripping it all out and starting over because it'll be anaerobic and basically useless.

My plants loved the dirted tank, but honestly, it's more hassle than it's worth. If I had to do it again, I'd just grab some play sand and root tabs. I'm not a fan of those terrac balls either - the iron in them isn't really accessible to plants. Root tabs, on the other hand, are made from ferrous gluconate, which is way more plant-friendly. So, grab some play sand, root tabs, and a good liquid fert, and you're golden. A 50-pound bag of play sand is like 7 bucks, and a pack of root tabs is 10 bucks - you can't go wrong.

[rivulet]

I'm curious about carpeting plants or amazon swords - will they still root well in the sand?

[boomer]

I agree with Colin that using soil in an aquarium doesn't offer any real advantages. In fact, it can lead to significant issues, like ammonia spikes that can persist for months and pose a risk to fish and invertebrates. The potential benefits just aren't worth the risks.

The fertilizer in potting soil is also a concern, as it's formulated for terrestrial plants with different nutrient requirements. Terrestrial plants need nitrates, which aquarium plants don't require. Using this type of fertilizer in an aquarium can lead to algae problems.

Aquatic plants will thrive just as well in inert sand or fine gravel, with or without substrate fertilizer tabs or liquid additives, depending on the specific plant needs, lighting conditions, water hardness, and fish load.

[rivulet]

I'd recommend a layer of about an inch of lava rock under the soil, it's inert so won't affect the plants' rooting. This will just provide pockets to prevent the soil from compacting, then you can add your baked soil on top.

[hillsman]

I agree with Colin that using soil in an aquarium doesn't offer any real advantages. In fact, it can lead to significant issues, like ammonia spikes that can persist for months and pose a risk to fish and invertebrates. The potential benefits just aren't worth the risks.

The fertilizer in potting soil is also a concern, as it's formulated for terrestrial plants with different nutrient requirements. Terrestrial plants need nitrates, which aquarium plants don't require. Using this type of fertilizer in an aquarium can lead to algae problems.

Aquatic plants will thrive just as well in inert sand or fine gravel, with or without substrate fertilizer tabs or liquid additives, depending on the specific plant needs, lighting conditions, water hardness, and fish load.

I'm not convinced that using soil as a nutrient layer is entirely without merit. Providing plants with a rich source of nutrients in an otherwise barren tank has to be beneficial, right? I mean, sure, you can add these nutrients in other ways, but that doesn't change the fact that plants will thrive with a soil substrate beneath the sand or gravel.

[oldraider]

Down the line, the soil's nutritional value dwindles and it can become more of a liability than an asset, requiring replacement. A simpler approach is to use sand or gravel, supplemented with root tabs, which provides a more sustainable solution.