The only thing better than watching brightly colored fish swimming in a clean, clear, aquarium is watching those same fish swimming in and out of a dense grove of bright green water plants. With plenty of places to hide and explore, the fish seem even more vibrant. But beyond creating a more natural-looking environment, healthy green plants also help to give your fish a healthier aquarium ecosystem.
All animals breathe in oxygen and exhale carbon dioxide while green plants take in carbon dioxide and release oxygen. This occurs underwater as well as on land. When you add filtration and aeration to your aquarium you remove the chemical wastes the fish leave behind, as well as adding oxygen to the water. In a healthy pond or stream, plants do both those jobs without mechanical assistance. They can do the same in a well-planted aquarium. In fact, two things you need to be concerned about when you add plants are (1) that your filter is not taking out the wastes the plants need to grow; and (2) that through aeration you're not depriving the plants of carbon dioxide.
Put In Plants Before Fish
If you intend to put plants into your tank, do it before adding fish. First, the larger the tank the better. Plants will quickly crowd even a 25-gallon tank. A finer grained gravel will hold the plants better. Contour the gravel so it's higher toward the back of the tank – say, 2 inches deep in front, 4 inches in back – so you'll be able to see all of your plants. Add some aquarium plant fertilizer, available in stores that sell the plants, to the gravel. The amount will depend upon the brand you use.
Check the PH
Check the pH of the water you're going to use. It should be neutral, around 7 or slightly less. If not, ask the fish store for some water softener. Fill the tank about half way, high enough so the tops of the plants will be buoyed up but not so high that you can't get your hands easily into the gravel. Secure the plants in the gravel. While they might look straggly at first, don't plant clumps of vegetation. Single plants will develop and their roots and rhizomes (the parts of the plant that produce new plants) will spread on their own. Getting the plants to stay in the gravel is also easier if you plant individual plants rather than full grown buoyant fronds that will float up out of their positions. Some suppliers sell plants rooted in rock so that all you have to do is set the rock into the gravel.
Once you're satisfied with your plantings, fill the tank. At this point there's no reason to turn on your filter. Make sure the water temperature is right – what's good for the fish you're planning to put in is all right for most plants (between 70 and 80 degrees Fahrenheit). All your plants need then, like plants in a pond, is light and food.
Your fertilizer has provided some food for now. As for light, this is one of the most difficult of your plants' needs to supply in an aquarium. Most aquarium hoods and regular fluorescent lights do not provide nearly enough light to sustain plant growth. They are made for looking at your fish. You will most likely need double the wattage – by a popular reckoning, 5 watts for every gallon of water.
Lights Are a Necessity
Grow lights or daylight lights are absolutely necessary to provide the plants with the right range of the light spectrum. If you have glass separating your light from the tank water, it's best to remove it or the glass will block some of the light. One of the best ways to accomplish all of this is to have no cover at all on the tank and set a plant nursery light fixture above the aquarium. This means you'll have to avoid buying fish that are good at jumping out of the tank, but it also means that your plants will grow out of the water, creating a beautiful water garden.
All this light, of course, will stimulate the growth of algae. So a few algae eating fish will go far in reducing its growth. So will a few floating plants whose roots will absorb the excess nutrients floating through the tank.
Now test your water's pH. It should be pretty near a neutral 7. Start up your filtration and add your first fish. Keep regular checks on your pH and nitrates and follow the procedures for setting up a tank without plants. As your plants grow, they will be able to handle more fish waste so adding fish will not produce the shock on your tank's system that adding fish alone would. The plants will be providing the normally difficult biological filtration by breaking down the fish waste. This will also allow you to keep more fish in your tank than you would without healthy plants.
What plants to plant? Hundreds are available. Some of the easiest to maintain – vallisneria, elodea, hygrophila, and echinodorus oriental (plants, unlike fish, usually go by their Latin names) – are easy to find in aquarium shops. For the more exotic plants, supply houses can be found in aquarium magazines or on the Internet. Tropica Aquarium Plants has an especially useful Web site that has photos of the plants, their temperature, pH, and light requirements, and their relative difficulty to maintain.