The single most infuriating problem in your aquarium is likely the ongoing battle against algae. Left unchecked, it can cover the glass - in colors ranging from black to bright green - making viewing your beautiful inhabitants impossible. It can also quickly cover the decorations, diminishing the appeal of the entire environment.
Some algae is easy to remove. All you need to do is scrub. To help keep water clean, use of a premium grade carbon will help reduce dissolved organics and slow the return of algae. However, if certain types of hair algae appear in your aquarium you may have a persistent problem that requires tougher measures.
Many aquarists who encounter hair or other tough algae treat the symptoms, not the problem. For example, they may bleach all their decorations and gravel and then treat the water with a dechlorinator, placing the health of their fish at risk, only to discover the algae making a fast comeback within days.
Avoiding Algae Problems
Most phosphate comes from three sources: tap water, fish food, and carbon. In the case of city water, the municipality may actually be adding it to protect its pipes. In well water, phosphate often come from the leaching of lawn and garden fertilizers.
To avoid unwanted phosphate levels, make sure no uneaten food is to remain in the aquarium. To reduce or eliminate phosphate already present, commercial phosphate removers can be effective. Of course, an excellent way to start is by using water purified through reverse osmosis (RO), and then using it for regular water changes.
The right choice of filter media can also make a big difference in phosphate levels: