Understanding the balance is the key to any planted tank. Any successful planted tank will be a balanced tank. These are a couple of things that the hobbyist often hears about, but many do not understand them or their implications. The purpose of this article is to introduce the reader to the balance, explain why it is important, and how to achieve this balance.
First, what does the balance consist of. The balance in question is the proper proportions of light, carbon dioxide, and nutrients. Plants require all three of these things in order to survive and grow. In order for the plants to take in the nutrients, there must be CO2 and light present. When any one of these three things is out of proportion there will be an outward sign to let the hobbyist know that something is not in balance. The amount of nutrients and CO2 required will be dictated by two things; lighting level and biomass of the plants, therefore, the appropriate levels for nutrients and CO2 will be different for every tank.
This brings us to point number two; why the balance is important. Plants, unlike algae, need CO2 in order to photosynthesize, without the presence of CO2, the plants cannot take in the nutrients and thus it leaves them for algae to use. Likewise, if there are too many nutrients present for the amount of CO2 in the water, the plants will not be able to use it all up and some will be left for the algae. Light comes into play in that the more light there is, the faster many plants will photosynthesize. Because of this, there will be a greater demand for CO2 and nutrients. So as there is an increase in light, there must also be a proportionate increase in CO2 and nutrients. Just as each one of these elements can be too high, they can also be too low. If the lighting is too low then there will be an excess of CO2 and nutrients, and there will be dying plants. If nutrients are too low (as in 0), then the hobbyist will have a situation where there is nothing for the plants or for the algae. In a case such as this the hobbyist will get a nice thick green mat of cyanobacteria, also known as Blue Green Algae.
So, how can this balance be achieved. This is something that will require the diligence of the hobbyist. First it is important to understand that the answer to plant problems is rarely a result of insufficient lighting. This issue, though, can be resolved simply by choosing plants that are appropriate for the light level. As for nutrients and CO2, these issues will require that the hobbyist watch the tank carefully, If algae starts to appear then either a decrease in nutrients or an increase in CO2 will be necessary. If there have been problems with nutrient deficiencies in the plants, the the answer must be to increase the CO2. If, however, there have been no nutrient problems in the tank then a reduction in dosing may be called for. There exists a couple of dangers in this portion of understanding the balance though. One of these dangers is the assumption that in order to achieve a balanced tank the hobbyist must dose nutrients and inject CO2. This, however is erroneous thinking. It is important to remember that the nutrient and CO2 levels are dependent on the biomass. If a tank has high lighting because of the types of plants that have been chosen, but there are only a very few plants, then there will not exist a need for as many nutrients. The plants have a maximum rate at which they can absorb the nutrients, and as a result, there are excess nutrients, they will be used by the algae. By the same token, in a lower lit tank, the levels of CO2 and nutrients will also need to stay low. In many cases the fish waste and the fish themselves will provide sufficient nutrients and CO2 for the plants. In a case such as this, the high tech approach to planted tanks is completely inappropriate and should not be used. This is the biggest danger that many aspiring planted tank hobbyists fall into, they learn about nutrient addition and CO2 injection and assume that it must be applied to all planted tanks period. Doing this shows a lack of understanding of how to balance a planted tank.
When the hobbyist understands what the balance is and understands that the balance level for every planted tank is different then that hobbyist is well on their way to a successful planted tank. Understanding this balance will allow the hobbyist to keep the full spectrum of planted tanks, from very simple, to high tech. Understanding this balance will also save the hobbyist from hours of frustration resulting from the upward spiral of higher light leading to more nutrients leading to expensive CO2 equipment. So as a hobbyist, understand the balance, and enjoy a beautiful planted tank.