Aquatic Plants - The Science Backstory

In my last blog entry, I covered the basics of Aquatic Plants in aquarium life. This week, I will cover the nuts and bolts of how plant life affects the environment. In other words, the science behind the curtain of tank walls. So, let's hop right in with the first topic: Carbon Dioxide.

CARBON DIOXIDE (CO2)

Without carbon dioxide, plants cannot perform photosynthesis (the process where they turn light energy into energy that they can use). Most plants will do well with the carbon dioxide produced by breathing fish and other animals in the aquarium, but there are of course exceptions. Some aquarists use CO2 injections to promote plant growth. This can produce wonderful results when balanced with sufficient lighting and necessary nutrients. Even plants that would survive without any additional CO2 can start growing much more rapidly when they receive extra CO2. CO2 can come from fermentation or from a gas cylinder filled with liquid CO2. 

Fermentation
Producing CO2 through fermentation is actually quite straightforward and can be carried out even by aquarists on a limited budget. You will need a 1.5-2.0 liter plastic bottle. Poke a hole in the cap and let an airline tube run through it. (The attachment must be airtight.) The airline should ideally have a non-return valve. Fill half of the bottle with water. Shake in ½ cup of sugar and ½ teaspoon of baking yeast. Secure the cap and wait for the fermentation process to start. It should be up and running in no time, just like when you bake a loaf of bread. When gas starts to evaporate through the airline, attach an air stone to the tube and place it in the aquarium. The fermentation process will normally provide the aquarium with plenty of carbon dioxide for at least two weeks. 

Healthy Aquatic Plant Environment

NUTRIENTS

Just like terrestrial plants, aquarium plants need nutrients to survive.

Macro nutrients: Nitrogen, Phosphate, Potassium
Other nutrients: Boron, Iron, Nickel, Zinc

In addition to the elements mentioned above, plants need trace elements of many other elements as well. If you fail to provide your plants with all necessary nutrients, it can lead to stunted growth, yellow leaves or even prove fatal. So, how can nutrients enter the aquarium? Nutrients are present in tap water and well water.  They are present in fish food (and will therefore also be excreted by fish). Nutrients are present in potting soil and aquarium substrate. You can purchase special fertilizers intended for aquarium use.

Before you decide on using fertilizers, keep in mind that simply filling your aquarium with a lot of fertilizers will not aid plant growth. Fertilization must always be balanced with light and carbon dioxide. It is also very important to purchase a special aquarium fertilizer, since fertilizers for terrestrial plants contain too much nitrogen which will cause algae growth and injure the fish. 

SUBSTRATE

As I pointed out earlier, some aquarium plants must be planted in the substrate or in pots, while others grow attached to rocks, driftwood etcetera. There are also floating plants and plants that can grow in several different fashions. If you want to keep plant species that need a substrate to grow in, ideally chose a substrate where the particles are 1.5-3.0 mm. There are naturally exceptions to this rule, but many plant species can not tolerate finer substrates since their roots cannot handle anaerobic conditions well. When the particles are 1.5 mm or bigger, it is easier for water to circulate which prevents clogging.

When it comes to substrate depth, the requirements vary a lot from species to species. The popular Amazon Sword, will for instance grow quite big and need to be rooted in at least 8 cm of substrate.

Amazon Sword

PREVENTING DISEASE

Unhealthy Aquarium Plants

Only purchase vegetation that look healthy. Don’t buy flora from aquariums where the fish seem unhealthy. Plants can carry malicious microorganisms and infect your fishes. If you want to feel safe, sterilize the plants before you place them in your aquarium. You can for instance use a dilute solution of potassium permanganate (provided that you have plant and fish species that can handle traces of potassium permanganate). Keeping a plant in potassium permanganate for 10-15 minutes will kill most malevolent microorganisms.

Healthy Fresh Water Aquarium Flora

Remove all damaged leaves before planting. It is better to remove a lot of leaves than allow them to decay and pollute the water. Don’t panic if most leaves die, turn yellow or dissolve after planting. The shock of being repotted can make plants lose their leaves, but they’ll grow new ones.

That's it for this week!

Sources:

http://www.thetropicaltank.co.uk/plantbas.htm

http://www.aquaticcommunity.com/plants/grow.php

http://www.aquaticcommunity.com/plants/aquarium.php