Step one: Keep your cool! Once fish disappear in green water, we often act with a sense of urgency. We tend to overcompensate with large water changes and other big ideas. In most cases sudden BIG CHANGES in the aquarium have negative consequences.
The larger the change, the greater the resulting biological imbalance
Small, gradual actions allow for the fish tank to adjust more quickly to the biological changes.
The most immediate threat of green water is oxygen depletion. Green water is a free-floating algae bloom and algae takes up oxygen just like any other plant. Creating surface agitation in the aquarium can easily increase oxygen levels. Adjusting the filter return to increase surface water movement will increase available oxygen in the tank. Further, the tank temperature can be lowered a few degrees increasing the water’s capacity to hold oxygen.
Follow these steps to clear green water
- Keep water changes at about 15 – 20% every other week.
- Remove waste from the tank with an aquarium siphon.
- Remove nitrates, as this is the primary food source for algae.
- Cut feeding to once every other day. Don’t feed more then the fish can eat within about one minute.
- Decrease the lighting period to no more then 6 hours per day.
Following the steps above will put your aquarium on a path to recovery.
Preventing green aquarium water
Once the tank has cleared up future green water outbreaks can be avoided by limiting the amount of waste in the aquarium and keeping nitrates as low as possible.