Create a Thriving Eco-System in your Water Tank

Aquatic Plants

The growing capacity of your garden does not have to be limited to what can be grown in the soil. Plants that grow in water not only add to the aesthetic appeal, but they also aid the overall functionality of the water tank.  Advantages of Water Plants include:

  • attractive
  • improve water quality (acts as filter of unwanted substances)
  • helps eliminate algae production
  • provide food & shade for fish
  • prevent water from overheating
  • overall less maintenance required



Algae Prevention

If you find you have an increase of algae on the pond, here are some possible reasons:
  1. You have too many fish. Koi need 200 gallons of water per fish to reach 6-8”. Goldfish need 100 gallons/fish.
  2. Not enough coverage on the pond surface, which should have 60% coverage from floating plants or shading.
  3. Not enough aeration, especially in the lower half of the tank.
  4. You are overfeeding your fish (They should use a “spring-fall” lower-protein feed between 50 & 60 degrees). Only feed every 3-4 days, what your fish can eat in 3 minutes.
  5. Stop feeding your fish once the tank drops below 50 degrees, this allows them to go into their winter slowdown without food on their bellies. Full guts could harm or kill your fish.
  6. All browning water plant debris needs to be removed. This includes trimming off segments of water hyacinths. This also includes pruning back most permanent water plants in December to a 6” height.
  7. Do not fertilize water plants during Nov, Dec, & Jan. This is also their quiet time!
Algae takes over quickly. Don’t put off these winter adjustments. It will only increase as the winter sun hits the tank. Remember that algae forms rapidly from sun exposure & fish/plant nutrients.


Types of Plants that grow in Water

The advantage of investing in water plants is that you are able to further enjoy and reap the rewards of your hard work. Keep in mind that 60% water surface coverage is ideal for these plants. There is an array of different plants that grow in the water and that suit different environments.

  • Floating Plants
  • Marginal Plants
  • Submerged Plants
  • Oxygenating Plants

Floating Plants

water hyacinth

  • full sun
  • tender plant
  • grow and spread rapidly
  • may not last through the winter
  • can be invasive to other plants (may be illegal to grow in certain locations)
  • enjoy crowded spaces, do not enjoy too much space
  • trim off any brown leaves and lobes
  • you can use water hyacinth in your biological filter (the top of your waterfall)

water lettuce

  • full sun & light shade in warmer temperatures
  • tender plant
  • quick growth rate (good coverage for price)
  • may not last through the winter


  • should be grown in full sun (love sunlight)
  • slow growing perennial
  • aesthetically pleasing (may not bloom in water tank)
  • colder climates, winter: keep plant dormant and cool w/o freezing plant
  • lowered to bottom of water tank during winter

water lily

  • full sun
  • perennial, easy to grow
  • aesthetically pleasing, but needs full sun to bloom
  • place in back of water tank for the most sun
  • shallow rooted plant
  • lowered to bottom of water tank during winter

hardy water lily

  • blooms spring through fall (dormant fall through winter)
  • easier to grow than tropical lilies (require a lower temperature of 60 degrees)

tropical lily

  • dormant in winter (can be left in water/stored)
  • larger and more extravagant, fragrant
  • flowers are in bloom for longer periods (1-2 months)
  • have higher chances of producing multiple flowers at once


  • moderate sun
  • perennial
  • invasive (can easily take up majority of water surface)
  • dormant in winter

parrot feather

  • highly invasive
  • low maintenance


  • full sun
  • perennial
  • doesn’t require much attention/care
  • difficult to control plant growth
  • heavy surface coverage
  • competes with other plants for nutrients
  • can climb on other floating plants and choke them
  • consider using floating barriers to prevent too much growth

floating fairy moss (azolla)

  • full sun
  • difficult to control plant growth (can double/triple its biomass in just a few days)
  • competes with other plants for nutrients
  • heavy surface coverage
  • fixes nitrogen
  • can climb on other floating plants and choke them
  • consider using floating barriers to prevent too much growth

Fairy Moss (Azolla) and Duckweed are types of highly invasive floaters. They tend to quickly take over the water surface and may end up competing with other plants for essential nutrients. When these floaters start to take over, they can be  added to  greenhouse bedding, a compost pile, or act as food for fish and chickens.


Marginal Plants –

these are the plants that grow in water and that we plant in our Floating Islands


  • full sun or partial shade
  • perennial
  • sensitive to cold


  • partial sun
  • easy to grow
  • edible when cooked
  • may attract whiteflies, if so cut the entire stem off and dispose of them outside

Submerged Plants

These plants that grow in water need to be planted in pots with a heavy soil mix, sitting 12″ below the water’s surface. Consequently, they require stands to hold them at the required height.  Unless you have a larger dome, the chances that you will see blooming is minimal. However, the leaf structure provides a lot of interesting surface coverage.  Do not use cement blocks for stands, or any other material that may adversely affect the Ph balance of your tank.

Oxygenating Plants

These plants that grow in water provide oxygen for your tank.  They should sit at least 24″ under the water’s surface to provide oxygen to the lower water regions of our tanks.  The primary oxygenators include anacharis, hornwort, and foxtail. The preferred technique in our tanks would be to suspend them inside a mesh bag (with a rock added to keep the mesh bag hanging low in the water).
Water plants not only add to the practicality of the water tank, they also increase the beauty within the growing dome. Until next time, Happy Gardening!

Common Fish for the Pond

Floating plants in the pond rely on the fish for their nutrients. The freshwater species of fish listed below are the most common types of fish raised in the Growing Dome pond. Local pet stores or fisheries are the best place to get freshwater fish, but they may also be purchased online and shipped to your door overnight.

  • Goldfish
  • Koi
  • Yellow Perch
  • Freshwater Sunfish, such as Bluegill
  • Catfish
  • Bass
  • Tilapia

We recommend waiting a few weeks after adding your water plants before introducing fish into your pond. This lets the environment adjust and be more stable for your fish. It is also important to treat tap water and test well water before adding fish to your pond. Water softeners are not recommended for your above ground pond because they replace electrolytes necessary to your fish (calcium and magnesium) with sodium, resulting in death of the fish.

Edible Fish

Edible fish can also be harvested in the Growing Dome, whether you have Aquaponics in your greenhouse or not.  Tilapia is probably the most common and will require more oxygenation than just goldfish.  You must also keep your tank above 50 degrees or they may die, but they will add a sustainable source of protein to your diet, while also giving your plants additional nutrients!  Please do your own research on food safety, when consuming fish from your Growing Dome.