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Understanding green water


It is so frustrating – you have set up your aquarium, added your beautiful fish then the water turns green. Not just a little bit green, but a bright yet cloudy, pea soup green and you can’t even see your fish. This is the result of what is known as an ‘algal bloom’.

This green water in your aquarium is ugly, and it’s bad for your fish.

It’s simple enough to deal with, but can return in a flash if you don’t do something about the underlying cause.

Aquarium treatments, such as Green Away, are a helpful short-term solution, but it’s important to be clued up on the causes so you can accurately treat these problems and prevent further outbreaks.

There are two primary causes of green water; too much light and too much waste. Algae use light, and chemicals from decaying waste to reproduce and grow. Control these factors and you’ll solve your green water problems. 

But my aquarium is green now – what can I do about it?

  1. Start by doing a small (10%) water change - tap water also contains nitrates so big water changes only re-introduce the algae food. Do this every 2 days for a week to gradually reduce the algae from the water while you take the following action:
  2. Deal with your light levels. As recommended above, put a timer on to reduce the hours the water is exposed to light and ensure your aquarium isn’t exposed to direct sunlight.
  3. Reduce fish feeding for a few days and ensure all left-over food, dead plants or fish are removed promptly.
  4. Treat with Green Away which kills the algae then binds it together so it can be trapped in the filter. Ensure your filter is coping with the additional muck. Clean the foams and change the filter cartridge regularly as they will be dirtier than normal. 

Here are some other things to consider when experiencing green water:



Extreme cases of green water, and the use of some green water treatments, can lead to a lack of oxygen in your aquarium; with deadly results if left unchecked.

Introducing some form of aeration via an air pump and air stone or bubble wand will make your fish much happier and healthier.  



Ongoing prevention