Algae Causes and Treatments for Aquariums

Glass Algae

Green spot is a typical form of seen in freshwater aquariums at home. In any aquarium, a tiny quantity of this sort of green is natural and anticipated, but an overgrowth may be controlled and avoided.

Characteristics and Causes

Spot algae are seen as circular, thin, bright green spots that adhere strongly to the surface of the glass and other hard surfaces. Typical causes are excess light and excess nutrients.

Low phosphates are most likely the cause of green spot algae on plants in your aquarium. If it's only on the glass and not on the plants, clean the glass and you'll be OK.

Prevention of Spot Algae

Use these tactics to prevent spot algae:

  • Regular water changes
  • Regular aquarium cleaning
  • Avoid overfeeding fish

The greatest preventive methods are regular tank cleaning and water changes. More significant issues can be avoided if abrupt algal bloom is addressed quickly.

Treatment for Spot Algae

Scrub or scrape off surfaces to get rid of spot algae. Spot algae can only be removed manually. Scraping with a razor blade on glass tanks is quite effective. In acrylic aquariums, sharp things should be avoided. Instead, use a plastic razor, a cotton pad, or a scouring pad that is extremely delicate.

Tank treatment: Increase phosphate dosing slightly in your estimative index (EI) fertilizer regime.

Spot treatment: Turn off the filter; use one of these three options, wait five minutes, and turn on the filter.

  1. If you have phosphate mixed in a solution, you can turn off your filter and dose your phosphates directly on the area that’s affected.
  2. If you have dry KH2PO4, mix your EI dose with tank water just enough to make it dissolve, then pipette/syringe it onto the affected area.
  3. If you do not have a phosphate solution, your alternative is a Fleet enema. Use 0.3 milliliters of enema per 10 gallons. Do this daily until it's gone, since you have no fertilizer regime. Do 50 percent water changes every third day to help keep the from getting out of control during this treatment.

If the algae keeps returning to the treated region fast with alternatives 1 and 2, you'll need to up the phosphates in your dosing routine, unless you're happy with spot treating the area every dosage.

Option 3 exposes you to the danger of nitrate deficiency during treatment owing to your lack of regular macro dosage. This impact is mitigated by a large fish load. If the nitrates continue to drop, Java ferns will blacken at the tips and melt a little.

Using the Estimative Index (EI)

The estimative index is a simple way of supplying nutrients to a planted tank. The concept behind EI is to simply introduce a tiny surplus of nutrients into an aquarium over the course of a week, followed by a substantial water change (such as 50%) at the conclusion of the week. This nourishes the plants by flooding the water column.

It is not essential to measure particular nutrient absorption rates. You can keep track of a variety of nutrients without ever needing to use a test kit. Aquarists use the same method with discus and other fish that require a lot of food to develop and reproduce. Once the hoses are out, a 50 percent water change takes roughly the same amount of time as a 25 percent water change. The changes in time and labor are minor.

EI helps to prevent nutrient deficits in plants and allows them to flourish freely. The majority of algae problems are caused by plant shortages rather than high nutrient levels (ammonium is a potential exception). Overabundance of light and, most commonly, inadequate CO2 monitoring and dosage are other problems for algae.


"Algae in the Planted Aquarium. Greater Washington Aquatic Plant Association." ;