Live Aquarium Plant Tips
The benefits of live aquarium plants over artificial in an aquarium are numerous. They are closer to the animals' natural environments, are less likely to harm the fish, can lower nutrients in the aquarium over time, provide grazing and breeding grounds, and are visually more dynamic than plastic plants or silk plants. However, they also require more care to keep them healthy. Live aquarium plants can be damaged by some fish and other animals and are not suitable for all aquariums.
Like any animals kept in aquariums, plants have their own needs and requirements. This guide is meant to provide general information so be sure to research any plant addition to your aquarium. Plants are comparable with corals in saltwater aquariums in that the lighting, placement, growth and water chemistry should be carefully chosen and monitored.
Proper lighting is perhaps one of the most important things we can provide for our plants. Lighting requirements varies from plant to plant. A number of "rules of thumb" circulate regarding the amount of lighting needed, most notably "rules" based on wattage per gallon. It is said that low light plants need 1-2 watts/gallon while high light plants need 4-5 watts/gallon. This rating is inaccurate and out-of-date. Newer high-efficiency fixtures like LED technology uses low watt bulbs but can be much more effective than fluorescent lighting.
The spectrum of the bulb is more important than the wattage of it. Plants tend to prefer bulbs with a Kelvin rating of 5500-10000K. This refers to the "color temperature" of the bulb; plant bulbs usually have a slightly yellow color as opposed to bulbs used in saltwater reefs systems that are more bluish. The depth of the aquarium, clarity of the water, reflectivity and other factors contribute to the lighting needed and the plants that can tolerate it. For example, deeper aquariums should have lower-light plants or more intense lighting than a shallower aquarium of the same volume. The "photo period" (length of time the lights are on) should be about 8-10 hours in most cases.
Most freshwater planted aquariums use natural substrates like Fluorite or freshwater sands. Iron-rich substrates are available specifically for planted aquariums. Avoid using large-grained substrates.
Plant Selection, Placement & Planting
Just as with fish, plants come from different environments and will thrive best in an aquarium that replicates this environment. Some prefer soft, slightly acidic water while others can tolerate a high pH and harder water. Some fish also eat or uproot plants and should either not be kept with live plants or plants that are easily replaceable or fast-growing should be chosen. Some plants grow very slowly while other grow quickly and may need to be pruned and "harvested" regularly.
While most plants can be planted in the substrate, some prefer different levels and have different growth patterns so the "aquascaping" in the aquarium should be considered. Plants are often divided into "foreground" (compact plants that remain shorter and are usually planted in the front of the aquarium), "mid-ground" (plants that grow to or can be easily pruned to a moderate height) and "background" (larger plants that serve as a backdrop in the aquarium). Some plants, particularly mosses and some Anubias swords, will grow onto hard surfaces like rocks or driftwood while most can be planted into the substrate.
While planting your new plants, take care to not damage their roots. A small hole can be dug in the substrate to place the plant into and then filled in much the same way a flower would be planted in a garden. Some plants grow from bulbs rather than roots and the bulb should only be about 2/3 buried in the substrate. Bunched plants that grow from cuttings rather than roots can likewise be planted in the substrate from one end, either in a bunch or individual stalks. Weights are available to help some plants stay in place while they become established. Mosses and plants that cling to hard surfaces can be held in place by floss or fishing lines until they "attach", at which time the line can be removed.
Supplements & Nutrition
Aquatic plant supplements and nutrients are available to replenish depleted water. Heavily planted tanks (over 70%) especially will deplete their nutrients quickly and may need to be supplemented regularly as the plants grow. Systems that are not heavily (under 70%) planted may not need many supplements since the fish in the tank will provide "fertilizer" through their food and wastes. One of the most popular supplements is iron, which is used to make chlorophyll in the plants' cells (that's the stuff that makes plants appear green). Some substrates are iron-infused and other iron supplements can be in the form of liquids or substrate-additives (like the fertilizer sticks used in terrestrial gardens). Take care to not overdo nutrients in the aquarium; they are no substitute for proper lighting and care. Plants use nutrients in relation to the amount of light they receive. Plants not exposed to enough light will not use the extra nutrient, but algae will. Excessive Phosphate levels will also encourage algae growth rather than healthy plant growth.
Carbon Dioxide is the most notable gas involved with keeping healthy aquarium plants and needs to be closely monitored in heavily planted tanks (70% or more). Levels of CO2, used by plants in photosynthesis, need to be conserved within the aquarium. Respiration from the fish and decomposition within the aquarium usually provides enough CO2 for lightly to moderately planted aquariums; compressed CO2 canisters and regulators can be used to inject CO2 into the water if necessary in heavily planted systems. Keep surface agitation to a minimum (canister filters can often be used to combat this) as this will limit lost CO2 to the atmosphere. Do NOT aerate the tank with an air stone.
Controlling algae while promoting plant growth can be a balancing act as algae is itself a plant. Algae is normal in any healthy system. Excessive algae growth can be caused by excessive lighting (too intense or on too long), high nutrient levels, high Phosphate levels (especially in the case of green water), poor light quality (seen most often with bulbs over 6-8 months old), improper temperature (in the case of cyanobacteria and some black algaes) and a number of other causes.
A number of the plecos traditionally thought of as "suckerfish" and "algae-eaters" do in fact eat and damage plants more than the algae you may wish to eliminate. Always choose fish and algae-eaters safe for planted tanks. Some examples are: Dwarf Suckermouth Catfish (Otocinclus sp.), some freshwater shrimp (Caridinia sp.), Siamese Algae Eaters (Crossocheilus siamensis) and some snails. Keep in mind that certain snails species will eat plants and others may breed rapidly and become a nuisance in and of themselves.