Aquatic Botany: Stage 2 – The Substrate

December 28, 2007

Alright; really this should be lumped in with Stage 1 – Basic Layout, but I was tired, so I didn’t get around to mentioning this.

Substrate, the soil or gravel or sand at the bottom of the tank that you plant your plants in to, will determine a great amount on how your plants grow, and subsequently affect how the tank itself matures. There are plenty of types of substrate, but some are better than others…

Let’s start with the bad, shall we? The worst of the worst is sadly the most common. It is the gravel. Gravel is made up of rocks, and who knows what these rocks can be. There could be cuprous (that is, containing copper) rocks that can leach out and wreak havoc on your invertebrates (shrimp, lobster, crayfish, etc), or the stones could be limestone (as was my case once) and react with any carbonic acid formed from CO2 diffusion in to the water. There isn’t really any engineering that goes in to your run of the mill Walmart gravel, and they will contain little, if any, usable nutrients for the plants to use. Now, I’m not saying that if you are a beginner in aquariums that you cannot use gravel. There are benefits to using gravel as a beginner. For one, if you are using an undergravel filter then this is actually probably one of the better choices, seeing as deitrus (fish crap) can make its way through the cracks in the gravel and in to the filter. It’s also cheap. Well, there are its positive aspects for you. Cheap and fish crap passes through it.

One step up and we have nothing more than playground sand. Sand rarely contains nutrients as well (though it can) and your average tube/bag of sand you can pick up at a hardware store has the potential of carrying some funky insects/parasites/bacteria/diatoms (not sure about that, if diatoms can lay dormant in sand). However, sand is just as cheap as gravel. Not only that, but sand is much easier to plant in. A tiny plant with tiny roots is more likely to take hold in sand than with 100x larger particulate gravel. Not only that, but sand has much more area. What I mean by this is that the surface area is greater in 1oz of sand than 1oz of gravel. This allows more area for bacteria to dwell in, and this is important for a healthy aquarium. Bacteria are an important part of cycling an aquarium, which is one thing that most eager new fish keepers don’t know/care about and thus incur fish loss. Why do you need to cycle an aquarium?

  • Fish poop has ammonia in it. Ammonia can kill fish.
  • As ammonia builds up, ammonia-digesting bacteria thrive and grow. These turn the ammonia (NH3) in to nitrite (NO2). NitrIte.
  • Nitrite is also not good for fish or other fauna. As ammonia dwindles and nitrites soar, ammonia-digesting bacteria begin to reduce in number, giving way to nitrite-digesting bacteria. These newcomers change nitrIte (NO2) in to safe nitrAte (NO3).
  • After a while, all the hazardous ammonia and nitrite will be gone, leaving only safe, plant-beneficent nitrate. Without letting the aquarium cycle, all the fish would be dead or in pretty bad shape (less a miracle).

So why does this mean sand is better than gravel when it comes to cycling? To put it simply, there is going to be more bacteria in sand than gravel and thus cycling will go much quicker. Also, if you want to see a helpful diagram of the cycle, see here.

Back on topic now…substrates…

Coming up next we have kitty litter. Yup. Kitty litter. I don’t know how or why this works, but apparently kitty litter can be used as a substrate in an aquarium with no ill effects and have some outstanding results with the plants. However, common sense must prevail. Come kitty litter has chemicals in it for various reasons (clumping, antibacterial, odor, etc) and therefore only certain brands and varieties should be used. One such brand I have recently (see above link) heard of is SpecialKitty. Can’t say if these are truly better than ordinary sand with fertilizer tabs or not, but it’s an option.

Before we get to the good good stuff, I will briefly mention Soilmaster Select (SMS). The stuff works like the good stuff, but not quite as well (experiences differ) and is cheaper. It’s made for fields.

Finally, we get to the commercially made, purpose engineered substrates.  A quick look at a retailer’s site shows just a few of the many options. These substrates are sharp looking, relatively easy to plant in, contain good amounts of nutrients right out of the bag, and some even have beneficial bacteria already in contained liquid to boost cycling. A few brands have gained notoriety, and you will often hear of Aquasoil, Flourite, and EcoComplete. I prefer the EcoComplete, though it is a bit more expensive. I just like the black look it has. If I could find the Black Flourite I would go with that, but I highly doubt I will find it. The other problem I run in to is that if I go with Flourite, I would need to strain and rinse it a bit before tanking it; a step that, though not too hard, I prefer to skip. Rinsing is a bit tedious and time consuming, but it does lead to a clearer tank once the water is put in.

Then there’s the entire fertilizer/supplement dosing deal. That’s later…


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