Aquatic plants require three main things in order to photosynthesis and flourish: Energy, nutrients and CO2. In an aquarium environment, energy can be provided by via flourescent lighting. Nutrients can be provided by dosing macro and micro nutrients and CO2 via “DIY” or pressurized CO2 systems or naturally. (CO2 naturally diffuses into the water column, along with oxygen). For plants to properly grow, they require all of these things to be properly balanced, or “Houston, we have a problem”. This is especially true if one has excessive lighting, and low CO2 and/or nutrient levels, as these conditions equal algae. As with water chemistry, the key to healthy plants is finding a balance between lighting (energy), nutrients and CO2.
Hobbyist have labeled the different balances low-tech and high-tech. Low-tech (also know as low light) setups utilize low lighting levels, low fertilization levels and (generally) no CO2 injection. High tech (also known as high light) setups utilize high lighting levels, high fertilization levels and pressurized CO2 injection.
Water changes. We do them religiously every week/month/year(!) but, why? Well like so many other things we do with our aquaria, there are many reasons, and for the most part, they are used to get rid of build ups of certain unwanted substances. One of the things that builds up are nitrogenous wastes. With the nitrogen “cycle” over a period of time nitrites will begin to build up. Although plants do absorb nitrites, unless you have a heavily planted aquarium they will not be able to cope with the average stocking levels in our aquairia. When we do a water change, we get rid of some of the nitrites. Another thing that builds up are hormones. Yep, hormones. Fish naturally excrete them and can be harmful, especially to fry and eggs when they build up. Also, what about all that gunk? You know what I am talking about. That pile of fish poop, food, plant waste and such that builds up in between that red rock and that piece of driftwood in your tank? Well with your siphon and gravel vacuum, you can take care of it!
So next time you are in the middle of doing a water change, think about all the good you are doing your fish!