Algae Explained

Algae is present in virtually every aquarium on the planet. Like all other plants algae needs light, heat, and a nutrient supply. In general terms algae do not compete with other plants as they have different nutritional needs than higher plants. In order to do well, they need much more nitrogen than their higher counterparts. Thus, they do not do well in an aquarium with favorable water conditions and plants that are growing well. If water changes are not done on a frequent basis, (once a week in my opinion is best) and other conditions in the aquarium are deteriorating such as organic breakdowns producing nitrates, the nitrogen levels will increase to levels that are intolerable for the higher plants. When this occurs, Photosynthesis slows, and the plants stop growing. Algae conditions are now favorable, and will multiply rapidly because these are the favorable conditions of algae. Because of their rapid growth rate, they rob the other plants of light and nutrients to the point where they cause further damage and eventually the plants die.
New aquarium setups are perfect for these conditions because the filter has not had time to be broken in and the normal breakdown of nitrogen by bacteria does not yet occur. New plants need a lag time to form roots and grow before they can produce oxygen and take up nitrogen to stabilize the new aquarium setup. The next section will now cover each specific algae and show why they are actually useful in solving existing problems in your aquarium.

Blue Green Algae

Blue green algae is present as blue green, violet, or brown-black covering plants, rocks, and substrate. They particularly favor the substrate where water circulation is poor and or the substrate is overfertilized. Other causes are that food and debris accumulate, oxygen levels are low, filters are poorly maintained or tap water high in nitrates is added. I use my fingers in a new tank setup to remove the slime from the plant leaves, if you don't then your plants will literally suffocate to death, and suffer from lack of light due to the covering. Cure? Remove existing algae, get your filter working properly to utilize nitrogen feeding bacteria, do frequent water changes, monitor water nitrate levels with a good test kit, and clean up excess debris with a siphon. There are no critters that will eat this form of algae.

Red Algae

Red algae grows in beards or off color green threads on plants, rocks, or driftwood. They are difficult to remove and they will kill the leaves of the plants. They thrive in hard water with a PH over 7.0, and again, a high nitrate content. Cure? Up your CO2 to acceptable levels, soften the water, get your PH down to 7.0 or lower, (usually accomplished with CO2 gas, buffers are not recommended by me) and methods used above for blue green algae concerning getting nitrate levels down.

Diatoms (substrate or gravel algae)

Diatoms grow in a thin brown layer on rocks, driftwood and plants. The culprit is lack of adequate lighting, and also lack of adequate oxygen and again, excess nitrogen. Cure? Up your lighting so that photosynthesis begins again and oxygen is produced and nitrogen products are consumed.

Green Algae

Light green floating algae more often than not is a result of overfeeding your fish. (most aquarists overfeed, take what you think your fish need in the palm of your hand and then cut that in half and that will be plenty) Other forms include the common glass algae. Cure? For green water a three day blackout of the tank (cover all so it is total darkness) with at least 40% water changes DAILY for those three days will generally take care of green water. Again, nitrate levels need to come down and water changes will help to do this as well as get rid of excess nutrients. For glass algae a good old fashioned algae scraper will take care of it.

Green Thread Algae

Unfortunately, this algae actually occurs only when all conditions are RIGHT with an aquarium, namely clean, well fertilized water! So their presence is a good sign? Cure? Remove by hand being careful not to pull up the plants with them in the process. Florida Flag Fish love this algae and will keep your aquarium clear of it. (Florida Flag Fish get to be good size and are territorial and semi aggressive so do your research on them first before adding to a community tank)

Bottom Line? (For all algae)

KEEP NITROGEN LEVELS LOW! How? By properly maintaining your filter, frequent water changes (once a week, thirty percent), less food during feeding and more frequently for those who think their fish are not getting enough, using a good test kit for nitrates and keep them betwen 3 and 5mg/L or below, not zero though, using proper lighting, using carbon dioxide in some form, using algae eating critters, NEVER overfertilize, and planting densely enough to begin with including some fast growing stem plants with newly set up aquariums.

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