Choosing the best substrate for your planted tank

[FinMaster]

I'm dealing with a substrate issue in my 75-gallon planted tank. The Controsoil base, which has been in there for years, has basically turned into mud. As a result, my plants - Amazon Swords, Jungle Val, and Corkscrew Val - aren't thriving like they used to.

My water parameters are pretty stable, with a pH of 8.0, and I've got a CO2 system with a controller. I'm looking for a new substrate that'll work well with my tetras and rasboras. I've been thinking of using organic potting soil as the base, topped with a layer of sand - possibly pool filter sand or play sand. Any thoughts or suggestions on this setup?

[BadgersSong]

I used to swear by the combo of 1" organic potting soil and 2" of sand, and it did work for me. However, I've come to realize that soil has its downsides. For one, it releases ammonia for a few weeks, which I actually utilized to cycle my tanks. If you have burrowing fish, be prepared for a mess. And after a year or two, the soil's nutrients tend to deplete, leaving you to supplement with fertilizers anyway.

These days, I've simplified things by using 2-3" of plain, un-rinsed play sand. The initial dust settles within a couple of days, and I believe it provides some nutrients to the plants. I then add root tabs as needed, usually every 3-4 months for heavy root feeders like swords. It's a more straightforward approach that works for me, and I've grown fond of its ease and effectiveness.

[BadgersSong]

I've had good luck with play sand from the hardware store. I've used Quickcrete and Black Diamond, which is actually a blasting sand. Some folks warn that it's too sharp for bottom-dwellers, but I've had no issues with cories and loaches over the years. That being said, your experience may vary. I've never personally tried pool filter sand, but I've heard it's a solid choice.

If you're looking for a completely safe option, go with a substrate specifically designed for aquariums. However, many people swear by regular play or filter sand, and it's significantly cheaper. I recently checked prices on Amazon and noticed that Black Beauty blasting sand, which I've used in the past, is no longer that much cheaper than aquarium-specific black sand. If I were in the market for colored sand, I'd probably just opt for the aquarium-grade stuff.

[coltin]

When it comes to substrate, I've learned that simplicity is often the way to go. I used to swear by 1" of organic potting soil topped with 2" of sand, but the drawbacks started to outweigh the benefits. Soil releases ammonia, which can be a real pain, and burrowing fish will turn it into a mess. Not to mention, the nutrients in the soil tend to give out after a year or so, leaving you to add fertilizers anyway.

Now, I just use 2-3" of plain, un-rinsed play sand. The dust settles out after a couple of days, and it seems to provide the plants with some nutrients. I add root tabs as needed - every 3-4 months for heavy root feeders like swords. It's not the most exciting solution, but it works. I've never had any issues with it, and it's far less hassle than dealing with plant substrates.

[Lachlan]

I've never had any personal experience with soil in a tank, but from all the reading I've done, it seems like it's more trouble than it's worth. I've come across a lot of people who swear by it, but the potential drawbacks just don't seem to be worth the risk for me. Sand or smooth gravel, on the other hand, is a much more straightforward option.

[FinMaster]

When it comes to substrate, I've learned that simplicity is often the way to go. I used to swear by 1" of organic potting soil topped with 2" of sand, but the drawbacks started to outweigh the benefits. Soil releases ammonia, which can be a real pain, and burrowing fish will turn it into a mess. Not to mention, the nutrients in the soil tend to give out after a year or so, leaving you to add fertilizers anyway.

Now, I just use 2-3" of plain, un-rinsed play sand. The dust settles out after a couple of days, and it seems to provide the plants with some nutrients. I add root tabs as needed - every 3-4 months for heavy root feeders like swords. It's not the most exciting solution, but it works. I've never had any issues with it, and it's far less hassle than dealing with plant substrates.

No, I don't think we need to get that fancy. Sand or a smooth gravel is probably the way to go, like Lachlan said.

[manal]

I've never had any personal experience with soil in a tank, but from all the reading I've done, it seems like it's more trouble than it's worth. I've come across a lot of people who swear by it, but the potential drawbacks just don't seem to be worth the risk for me. Sand or smooth gravel, on the other hand, is a much more straightforward option.

One of the main issues with using "soil" in aquariums is the general lack of understanding of what soil actually is and what it needs to be effective. Most store-bought garden soil is essentially just ground-up and partially composted mulch, often containing hardwood tree chips, bark, or pine mulch, with some sand added in. There's rarely any actual soil content, and even brands that used to be reliable are constantly changing their source materials. It's a real mess.

The problem with this type of soil is that it's mostly made up of light organic matter that's barely composted, lacking the clay or silt particles needed to hold nutrients long-term. This poorly composted organic matter can tie up beneficial bacteria for a while, releasing unknown substances from the trees it was made from.

If you're determined to use dirt in your aquarium, you'd be better off using riverbottom sandy loam or silty loam – essentially, dirt from right next to a river or stream. This type of soil has some clay content that can hold and bind nutrients, along with sand and organics that provide a good long-term structure. You can just dig it up, let it dry out and sterilize it a bit if you want, or use it as-is.

I'm not a fan of sterilizing, but a low-temperature bake at 175-200 F for an hour or so should do the trick without altering the chemical structure. Alternatively, you can just let it air dry for a while.

There's a simple test that soil scientists use to get an idea of the soil type, called the "spit test". Take a small amount of soil, spit on it, and rub it in a circle with your finger. You'll be able to tell if it's sandy, clay will feel slippery, and silt will be somewhere in between. Organic matter will be left as dark particles. It's a crude test, but it's effective with a bit of experience.

The point is, there's no consistency or understanding of the dirt itself, which is why people have such mixed experiences with using it in aquariums. I'd never use bagged "soil" except to modify existing soil that's lacking in organic matter or to help with pH. A bit of peat moss can help with acidification and adding organic matter to high-clay soil. Mixing sand into clay soil can also make it more desirable.

[FinMaster]

I've never had any personal experience with soil in a tank, but from all the reading I've done, it seems like it's more trouble than it's worth. I've come across a lot of people who swear by it, but the potential drawbacks just don't seem to be worth the risk for me. Sand or smooth gravel, on the other hand, is a much more straightforward option.

One of the main issues with using "soil" in aquariums is the general lack of understanding of what soil actually is and what it needs to be effective. Most store-bought garden soil is essentially just ground-up and partially composted mulch, often containing hardwood tree chips, bark, or pine mulch, with some sand added in. There's rarely any actual soil content, and even brands that used to be reliable are constantly changing their source materials. It's a real mess.

The problem with this type of soil is that it's mostly made up of light organic matter that's barely composted, lacking the clay or silt particles needed to hold nutrients long-term. This poorly composted organic matter can tie up beneficial bacteria for a while, releasing unknown substances from the trees it was made from.

If you're determined to use dirt in your aquarium, you'd be better off using riverbottom sandy loam or silty loam – essentially, dirt from right next to a river or stream. This type of soil has some clay content that can hold and bind nutrients, along with sand and organics that provide a good long-term structure. You can just dig it up, let it dry out and sterilize it a bit if you want, or use it as-is.

I'm not a fan of sterilizing, but a low-temperature bake at 175-200 F for an hour or so should do the trick without altering the chemical structure. Alternatively, you can just let it air dry for a while.

There's a simple test that soil scientists use to get an idea of the soil type, called the "spit test". Take a small amount of soil, spit on it, and rub it in a circle with your finger. You'll be able to tell if it's sandy, clay will feel slippery, and silt will be somewhere in between. Organic matter will be left as dark particles. It's a crude test, but it's effective with a bit of experience.

The point is, there's no consistency or understanding of the dirt itself, which is why people have such mixed experiences with using it in aquariums. I'd never use bagged "soil" except to modify existing soil that's lacking in organic matter or to help with pH. A bit of peat moss can help with acidification and adding organic matter to high-clay soil. Mixing sand into clay soil can also make it more desirable.

I've come to the same realization about those so-called "organic potting soils." I recently picked up a small bag to test it out, and I was shocked to find it had the consistency of ground-up tree bark – hardly what I'd call actual soil. It was a mess, to be honest. I had to cover it with sand or gravel just to keep it from floating on the surface.

Using the adobe clay from my yard would've been a better bet. I've heard some good things about DynaDirt Aquatic Planting Soil, so I'm considering giving that a try before I redo my 75-gallon tank. I'm thinking of combining laterite with some DynaDirt, topping it with sand, and then testing it out in some pots with plants in smaller tanks. We'll see how they do.

[BadgersSong]

I've had decent success with Miracle Grow Organic, but in all honesty, I think just using dirt from the yard can be just as effective. Of course, you've got to take the necessary precautions, but it's definitely worth a shot.