Dealing with Algae in Freshwater (i.e. not marine) Aquariums

Algae are primitive plants which come in a vast range of types, none the less they can be divided into a number of basic types. These are listed below, as each of the different types have slightly different causes, they require slightly different cures, but first some general dos & don'ts, which if followed will greatly reduce the risk of algae becoming a problem for you.

1. Do Not overfeed your fish - uneaten fish food will rot down and add algae promoting nutrients to your aquarium.

2. Do Not overfeed your plants -excessive use of plant foods will encourage algae (algae are plants too!)

3. Do carry our regular part water changes, we suggest 10 - 20% every week or so. When carrying out water changes use a gravel cleaner to stir up the gravel & remove debris.

4. Don't skip on water changes because everything's looking "OK"

5. Ensure consistent light levels by :-
a. Switch the light on and off at the same time every day, to give a light period of 10 - 12 hours per day.
b. Keep the tank in a dark position, away from natural day light.
c. Change light bulbs every 12 - 18 months (the output from most fluorescent tubes falls by about 50% in this time)

6. Try to encourage other plants, if growing well they will out compete the algae.

7. Remember an aquarium without any algae is a very unnatural environment, a small amount of algae is to be expected.

8. Algae thrive in disturbed conditions, avoid excessive or too frequent attempts to get rid of them as this can actually encourage them.

9. Biological control in the form of algae eating fish and shrimps can be very effective.

Green water algae - free swimming algae which discolour the water, in extreme cases producing a thick pea soup appearance.
Not too common in aquariums, where it occurs, it is often where the aquarium is in a very light room e.g. conservatory. The best cure - Pay particular attention to points 1, 2, 3 & 5 above. Turn off tank lights & cover tank with a blanket for up to 14 days if necessary. If using an external power filter, clean this out and ensure a good layer of polymer wool (Eheim "ehfisynth" is particularly suitable) is included in the filter media. Use of a suitable flocculent (which will make the algae particles clump together) will help Interpet "Filter aid" & "greenaway" are two such products, but there are many others.
NOTE - do not add water from a pond or similar out door water source to an indoor aquarium as this can often introduce green water algae's.

Hair Algae - long filamentous algae growing on rocks, plants and the glass, in extreme cases swamping the plants and preventing their growth.
The cure - regular physical removal by hand, pay particular attention to points 1 - 4 & 6. This type of algae generally grow where nitrate and phosphate levels are above optimum levels. Some regular, if possible daily, water changes will help. but don't exceed 20 - 25% of the aquarium volume per change.
If Nitrate & Phosphate levels are raised there are various commercial products available to remove them e.g. "Rowaphos" and "Nitrate minus". Algae shrimps can be very useful in removing hair algae proving you don't have any fish which might eat them.

Algae shrimps can be a great help in controlling hair algae.

Black Hair Algae - similar to ordinary hair algae but generally grows in short tufts particularly on the edges of plants and rocks.
The cure - as for hair algae, but in addition we have noticed that these algae's. can grow where heavy metal levels are raised. This type of algae can be associated with the use of hot water from a domestic hot tap. This can add traces of copper to the aquarium (instead always use boiled water from a kettle to warm water which is being added to an aquarium). Another possible cause is, over feeding of bloodworm & tubifex foods (both of which can contain raised levels of some metals.)

General Green algae (primarily on glass) - fairly short, usually fairly slow growing, algae which grows on flat surfaces and is most noticeable on the aquarium glass (not to be confused with blue-green algae).
The cure - physical removal, there are various scrapers available on the market such as algae magnets, and hand held scrapers, otherwise clods of filter wool can be used. We suggest that you clean your glass every week or so let the dislodged algae settle for ten minutes or so, and then remove with a gravel cleaner as part of your regular maintenance routine. Pay particular attention to points 5, 6 & 7 above.

Blue/Green (slime) algae - strictly speaking these are more correctly classified as cyano-bacteria. These "algae" form thick vivid green velvet like mats covering, plants, rocks, gravel and glass of the aquarium. This is probably the hardest type of algae to live with and cure.
The cure. regular daily water changes, remove as much algae as possible with each change. Introduce lots of fast growing plants to out compete the algae. We particularly recommend Hornwort & frogbit, which as floating plant helps to provide shade. Pay particular attention to points 1 & 2. Algae shrimps and the siamese flying fox (Crossocheilus siamensis) will also help. Cellpharm Algattack which uses bacteria to tie up algae promoting nutrients has also helped. A combination of all of the above usually works!

The siamese flying fox Crossocheilus siamensis - there is some confusion in the literature as to which is the true siamese fox, but this is the one you want in which the black line continues into the fork of the tail!

Brown algae - soft slow growing algae, often seen in newly established tanks.
The cure - usually appears at about the two or three week stage in new tanks, it will usually disappear on it's own after about a month. If not it can be easily removed with algae magnets, scrapers etc. Persistent brown algae will grow in light levels, so note point 5.

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