Healthy plants provide a lot of benefits to an aquarium. With great beauty they help the aquarium live up to its name as an enclosure that represents a natural aquatic environment. They provide a lot of surface area for beneficial bacteria to grow, aiding the nitrogen cycle, and they consume nitrates, the end product of that cycle, as nutrients. Fish and other aquatic animals respond naturally to live plants, often using them as hiding or breeding places. Plants also release oxygen in the water column during the photo period. Overall, plants provide well rounded balance for an aquatic ecosystem.
The "holy trinity" of growing healthy plants consists of balancing lighting, nutrients, and carbon dioxide.
- Lighting provides essential energy for photosynthesis (simulating sunlight)
- Choose the right light for the tank size and kind of plants and other aquatic life to be kept
- Brightness is measured in lumens, different plants have varying brightness requirements
- Color temperature (intensity of varying wavelengths) is measured in Kelvin, and different plants have varying requirements
- Keep a regular photo period schedule, for plants need consistent photosynthesis duration at the same time each day, establishing a natural rhythm of work and rest
- All plants require nutrients for growth and healthy functioning
- While nutrients come from the beakdown of plant and animal waste and uneaten food (nitrates), usually additional fertilizer is required, especially for fast growing plants that consume more nutrients
- Nutrient rich substrate, eg., Fluval Stratum, is helpful for rooting plants, yet sometimes root tab fertilizers placed among roots (2 to 3 times per year) can be helpful
- All plants, but especially epiphitic plants and floating plants draw nutrients from the water column, so liquid fertilizers are used to boost nutrient levels
- Bear in mind that adding more fertilizer than the plants can consume fuels algae growth
- Plants need CO2 dissolved in the water column for photosynthesis
- In nature CO2 is absorbed from the atmosphere, but in an enclosed aquarium CO2 absorption is limited
- Injecting CO2 into the water column enhances plant health and growth significantly
- Plant pearling occurs when plants are photosynthesizing and releasing oxygen faster than it can dissolve in the water column
- CO2 levels must be monitored, because excessive CO2 can be harmful to fish and other inhabitants
- Use a drop checker to measure CO2 levels
- Inject CO2 only during the daily photo period, and only as much as the plants consume
- During the night run aeration to supplement oxygen levels which plants use for respiration at night, as well as all other tank inhabitants
Many plants require regular trimming to keep them under control, especially fast growing stem plants
- To minimize the stress effects of trimming, trim fewer plants at a time, wait a week or so, then trim more plants
- When a lot of the plant mass is trimmed at the same time, a lot of plant tissue is damaged all at once
- The damaged tissue releases nutrients back into the water column in the same way a melting plant would, or as a dead fish adds a sudden nutrient load
- The beneficial bacteria suddenly have more work to do, and must gear up to break down what the plants release, leading to a bacteria bloom that can cloud the water column
- Meanwhile, the plants themselves are stressed/shocked by the trimming, needing time to recover and requiring less nutrients (if feeding with fertilizer, cutting back for a few days helps)
- While that's happening, algae can take advantage of the temporary imbalance in the nitrogen cycle, feasting on the excess nutrients in the water column
- Trimming to maximize density of newly planted stem plants, promoting thick bushes
- Trim low on the first cut, just above the first few leaves, they will then branch into two heads rising
- Trim again, this time cutting off below the newly branching head, and replant those with double the foliage
- After those plants with the double heads grow out, trim them so that the doubles will double again, making four heads
- Continue this process as long as desired
- The leaves of rosette plants can be trimmed as needed or desired, especially damaged leaves or those leaves plagued by intractable algae
- Cut as close to the rosette as possible and a new leaf or more will grow back
- Trimming for creating greater density is more hit or miss than for stem plants
- Epiphytic plants are slow growing, but can be trimmed for damaged and decaying leaves, but don't cut the rhizome
- Carpeting plants can be trimmed "lawnmower" style, wait for the plants to develop a good root system before mowing
- With mosses, cuttings do not float up to the surface, but sink to the substrate
- After trimming the cuttings can be siphoned out with a water change, or sucked up by a turkey baster
- Moss cuttings that are missed can get lodged in certain places and start growing again, which is not so good if it gets lodged in the carpeting plants and begins to take over
- Cleanup after trimming most plants, besides mosses, is quite easy
- Cuttings float to the surface
- Those cuttings can be scooped out with a net, careful not to scoop out small fish or shrimp or snails
Acclimation for New Plants
- Instead of planting right away, allow new plants to float for a few days
- While floating they are closer to the light, have more available CO2 which helps them in transition
- Plants have time to adjust to new surroundings, recovering from stress of being moved, and growing stronger
- Many plants will start growing more roots, preparing for planting, ready to grow
Importance of water changes
- Plants help reduce the need for water changes for managing nitrate level (in contrast to fish only tanks), because they consume nitrate as food
- Still, weekly 25% water changes remain beneficial for introducing new minerals that plants need into the water column