Re: Low-tech aquarium
Stan…in principle there is absolutely nothing wrong with using garden soil in an aquarium as a medium for plants. However, it does entail certain risks. You are right they may contain substances that could prove toxic to aquatic life.
However, soils behave differently when they are submerged and usually this just means that sometimes they don’t work very well as an aquatic planting substrate; even though they work perfectly well in your garden. Also, for instance, certain soils can cause metal toxicity or long-term turbidity depending on their composition and local water chemistry. But in short, the fertility of a submerged soil does not necessarily guarantee vigorous growth, in many cases it is the least toxic soil which provides the best growing conditions.
The advantage of using proprietary brands like John Innes is that they are guaranteed to be of consistent composition, and have been tried and tested and proven to be safe and work well as submerged substrates. This, in no small measure, is also due to their relatively high cation exchange capacity, which means that they have the ability to hold nutrients in a form plants can easily utilize.
However, there is nothing stopping you experimenting with your soil. You could use 2 litre drinks bottles one containing submerged John Innes, for instance, and another garden soil to compare growth rates of the same aquatic plant species. Obviously all other variables would have to be the same, so that you could be sure that any difference in growth rate is down to the soil alone. Whilst you are at it you could also keep an eye on water chemistry to determine if any toxic substances leach out; that is if you have access to the necessary test kits. But there is no need to be too scientific about it; you should get a good idea how well your soil works by observation alone.
Stan…in principle there is absolutely nothing wrong with using garden soil in an aquarium as a medium for plants. However, it does entail certain risks. You are right they may contain substances that could prove toxic to aquatic life.
However, soils behave differently when they are submerged and usually this just means that sometimes they don’t work very well as an aquatic planting substrate; even though they work perfectly well in your garden. Also, for instance, certain soils can cause metal toxicity or long-term turbidity depending on their composition and local water chemistry. But in short, the fertility of a submerged soil does not necessarily guarantee vigorous growth, in many cases it is the least toxic soil which provides the best growing conditions.
The advantage of using proprietary brands like John Innes is that they are guaranteed to be of consistent composition, and have been tried and tested and proven to be safe and work well as submerged substrates. This, in no small measure, is also due to their relatively high cation exchange capacity, which means that they have the ability to hold nutrients in a form plants can easily utilize.
However, there is nothing stopping you experimenting with your soil. You could use 2 litre drinks bottles one containing submerged John Innes, for instance, and another garden soil to compare growth rates of the same aquatic plant species. Obviously all other variables would have to be the same, so that you could be sure that any difference in growth rate is down to the soil alone. Whilst you are at it you could also keep an eye on water chemistry to determine if any toxic substances leach out; that is if you have access to the necessary test kits. But there is no need to be too scientific about it; you should get a good idea how well your soil works by observation alone.
