There is little doubt that an aquarium with flourishing plants is a pretty impressive sight, and one of the most common questions that we are asked is how to grow plants without excessive algae growth. Growing plants is easy as long as you follow some basic rules.
Unlike people or fish for that matter, plants are able to produce their own food by using light. Plants in your garden and those found in rivers all use the sun to achieve this, so in an aquarium what we are trying to do is provide and replicate the sun. The most common way to do this is through the use of a fluorescent tube. These tubes are not the same as those used to light your house, they have a spectrum developed to ensure strong plant growth. Aquarium plants need approximately 10 - 12 hours light per day. One of the most important things to remember about these tubes is that they only have a life between 12 and 18 months depending on the type that you are using. Itís not that the tube will not emit any light after this time, the problem is that the spectrum in the tubes changes and starts to inhibit plant growth but encourage algae growth. So if your plants have stopped growing and the algae is suddenly on the rise, it might be time to consider changing tubes. We recommend Power Glo tubes as they last for up to 18 months and are excellent for aquariums that are 18 inches in depth. For aquariums deeper than this we recommend using two lights or a single high output T5 light.
Feed the plants
Just like their outdoor cousins, plants in aquariums also require regular feeding, and although plants are able to use fish waste as a source of food this is incomplete and needs to be supplemented. The major source of nutrients that plants require is iron and one of the reasons that plants turn yellow is that they are deficient in this. The number of plants effects the rate of iron consumption, but most planted aquariums require iron to be supplemented once or twice per week. Iron aside there are also many trace elements that are found in water that help plants grow. Many of these are removed by biological filtration and need replenishing on a daily or bi-weekly basis. To get the best results from plant foods, you should use a combination. One that adds iron on a weekly basis and the other to replace trace elements. We find that both Seachem Flourish and Flourish Iron or Aquasonic Basic Grow and Daily Grow are good combinations for a planted aquarium.
A quick note, too much iron can be just as bad as too little iron so always follow the directions, or better still get an Iron Test Kit so you can accurately monitor the iron levels of your aquarium.
All plants require a source of carbon. This is typically obtained fromcarbon dioxide. Some CO2 will occur naturally in an aquarium, however an aquarium with several plants will deplete the aquarium of these carbonates quickly. Other factors such as filtration type and the amount of surface water that is disturbed will also play a role in how much carbonate is available for your plants. The best way to add carbonates to your aquarium is with a CO2 diffuser that injects CO2 directly to your system. Alternatively a lower cost option is to add a liquid carbon supplement such as Flourish Excel which is a liquid organic carbon source that does not impact pH.
Getting the Right Plants
It is pretty difficult to grow tropical fruits in a cold climate because the conditions are not correct and the same thing can be applied to your aquarium plants. Some plants require warm water to survive, and equally some plants will die if the water is too hot. Always ask if a plant is suitable for the type of aquarium that you have.
The only plants that will grow under water are true aquatic plants which sounds silly, but there are some plants on the market that are only display plants. These are not true aquatic plants and last for a maximum of about 2 months.
After buying your plants make sure that you plant them correctly by not covering the crown of the plant. (This is basically where the leaves start and if the plant has a sinker on it, then the gravel should be no higher then the top of the sinker.)
To grow successfully, plants need water movement. Not strong currents but enough flow to help to move nutrience towards them and waste products away from them. This can easily be achieved by positioning the outlet of the filter at one end of the tank and the inlet at the other to create a circular current, or small power heads can be positioned in the tank to achieve the same effect.
Like fish, plants need good quality water to grow well which means that regular water changes are essential. These changes remove phosphates and nitrates from the water that can cause major algae problems and inhibit plant growth if left unchecked. Another major cause of plant death is water with an acid pH. This quickly damages plants and no matter how much light and plant food you give them, they will not recover.
Plants also grow better when they are provided with a carbonate hardness of KH of about 60ppm. This can be achieved by using a Carbonate Hardness Test Kit and a some Carbonate Hardness Generator. The plants use the carbonates in the water, which means they require less carbon dioxide. A moderate Carbonate Hardness will also ensure that your pH remains stable.
This is an overview of what is required to achieve healthy plant growth. When followed, a lovely planted aquarium will result.