Hair Algae

(Unedited version)
Originally appeared in the November 2007 issue of
Tropical Fish Hobbyist Magazine

Hideous, hairy, stringy, matted, algae, the bane of the planted aquarium keeper. It can run all over the bottom of your tank and pull up your carpeting plants when you try to remove it. It can grow in huge nasty globs on the surface of your aquarium cutting out light. It can fill your tank and even sometimes trap and kill your fish. Of all the types of algae it's hair algae that causes the most problem for the most aquarists.

So what exactly is hair algae?

There are a number of algae species that grow into a hairy nasty mess. It's difficult to specifically identify algae because there are so many, they can look very similar, new ones are discovered regularly, and there's a lack of good reference materials to identify algae with. In fact algae is so diverse that some types of algae are more closely related to fungus or animals than they are plants. If you think crypts, vals and swords are hard to identify, try getting a good specific identification of your algae. In fact your nasty ball of hair algae may contain several different species of algae. For the most part then we have to talk about algae in general terms and descriptions.

The hair algae I'll be discussing in this months column can refer to any of the long stringy nasty green algae that can invade your aquarium. Algae are often discussed in terms of their color, which is caused by their pigmentation. Chlorophyll is a pigment whose predominance makes most plants, and green algae, green. Green algae can have other pigments but they have more chlorophyll. Even within the group of green algae the organisms are not necessarily closely related. Just because two types of hair algae look the same, they may not be related and different forms of treatment may be more effective for each type. You may have to experiment with several options before finding something that works.

Where does it come from?

Algae can come into your tank from many sources. Anything that goes in to your tank that has been in another aquarium or natural body of water could potentially have algae on it. This include plants, fish, snails or any other living thing in your aquarium and the water they came in with. Fish, shrimp and most animals will be your least likely culprits. Snails shells often have algae growing on them. Plants and any decorations and equipment that's been in another aquarium will most likely have some types of algae growing on them. There is even debate in the aquarium community as to what extent airborne spores might play in bringing algae in to the aquarium. There are lots of types of algae, its very small and can come in to your tank from many sources.

Reducing Hair Algae

The first thing you can do in your battle against it is to remove as much as you can manually. Depending on how much you have in your tank, what kind it is and if and where it's attached this can be a little difficult. If the hair algae is attached to your plants you can pull them out with the algae. Removing the hair algae will often take 2 hands, one to hold down your plant and one to pull off the algae. You can also remove parts of the plants that are heavily infested, but you don't want to remove too much of the plants as they are they are the warriors in your battle. Good healthy plants are a key to getting rid of and keeping away algae.

I like water changes as a next step. Most aquarium authors encourage water changes. If you have a problem with the buildup of excess nutrients, water changes will help that. Depending on the water you use it should also add some micro-nutrients to the tank.

There are some aquarists that believe in a low tech tank, water changes should be kept to a minimum for various reasons. One school of thought is that the water changes, change the chemical composition of the water quickly giving the algae the advantage since it adapts to changes in the environment faster than plants do.

Plants like to get used to one particular environment and stay that way. Changes mean their old leaves are no longer optimal for their surroundings, the more change the more they need to drop old leaves and grow new ones. When they have to do that they spend a lot more energy and the old leaves start decomposing and adding to the problem.

I still believe that regular water changes in any tank are good. 20 years ago I was in the low water change crowd. Some friends convinced me to try doing more water changes. I started doing them and believe my fish and plants have done better because of it and so I advocate for doing regular water changes. I think they benefits outweigh the possible disadvantages. If you do them regularly then they won't cause huge swings in your tank.

Speaking of water, what's your water like? In her book Diana Walstad indicates that algae have the advantage in water that's alkaline and has a high pH. If you have naturally soft water out of the tap that's a great advantage for you. For those of us with water like liquid rocks there are other options. First you can purchase or filter your own water. RO water is often used in planted aquariums. Usually it is mixed with tap or several additives are mixed with it to achieve the desired water conditions. Adding CO2 will also lower your pH and can be very beneficial to the plants but does require more tank care.

Another options and what I do in the majority of my tanks is to just grow plants that prefer the rock like water. Many plants will do well in this type of water, val hornwort, swords, mosses and native plants are some that grow well for me in hard, alkaline water.

Regardless of what type of water you have it's always a good idea to research your plants. I can't tell you how many times people will tell me of their plant growing woes and then send me a photo of a dying house plant in an aquarium. Many plants sold as aquarium plants aren't. Be sure to research your plants and fish before purchase or be prepared to spend money on things that just won't work. You need to have healthy aquatic plants to compete with your algae. New growth should be noticeable and should continue indefinitely.

Speaking of healthy plants, another method used to keep an aquariums algae down relies on optimal plant growth. In systems like the Tom Barr's Estimative Index, fertilizers, and CO2 are combined with good lighting in an effort to maximize plant growth, there by inhibiting the growth of algae. Doses are added daily to several times a week and large water changes are carried out weekly to ensure there are no excessive build-ups. Results can be impressive but this is a labor intensive way to grow plants. You have to stay on top of it to keep the tank levels consistent, and you will need to trim regularly to keep up with excess plant growth.

Another way to use desirable plants to curb algae is by letting your plants grow across some of the top of the tank or even out of the tank. More plant growth means less for your algae, and plants growing across the top and out of the tank have the added benefit of being able to use the CO2 in the air. Plants across the top of your tank can also provide shade, which can hurt some algae. Just be sure to leave enough light so your plants don't suffer.

Make sure you have adequate lighting for your aquarium and replace bulbs frequently. Most sources site 6 months to a year as a good time to change bulbs. Insure that your aquarium isn't getting sunlight from a window. Often a patch of hair algae can be linked to a passing period of daylight that streams in to a tank from an open window across the room.


Good aquarium practices are a key in fighting hair algae but you also may wish to employ a small clean up crew to aid in your battle. Several fish and invertebrates will eat at least some species of hair algae. Some of the ones that I've found to be successful are Florida flag fish (Jordanella floridae), Ameca splendens, and some mollies. Though most shrimp don't seem to eat it I've found that ghost shrimp often will. And if you want to try something really unusual the tiny crustacean gammarus will also eat hair algae.

Mollies are often available at local fish stores but the other fish may be hard to find. Look for people interested in livebearers or native fish the ALA and NANFA are good places to start looking. You can also check on line for auctions or shops or ask your local stores if they can order them for you. Once you have them all three fish are easily bred in the home aquarium.

Ghost shrimp can often be purchased at many aquarium shops. They are often sold as feeder shrimp. In the planted aquarium with smaller fish they can usually do very well. They even breed in the aquarium readily carrying their eggs and young fry under their bodies, eventually releasing tiny replicas of themselves.

Gammarus and the very similar looking Hyella are tiny freshwater shrimp. They are easiest to find in a local body of water. They are often in ponds natural and man made, in the plants purchased at nurseries that sell pond plants, and in many if not most natural bodies of water. Some fish will eat them but I've found that with small fish in the tank enough gammarus survive. Unfortunately they will also eat mosses so shouldn't be placed in an aquarium where you wish to grow them.

You may notice that there are several different methods for dealing with the growth of unwanted hair algae in the aquarium. Often I find that it's a slow process of making slight changes in different areas with small successes until finally a stable and satisfactory environment is achieved. Be aware that the advise you find is just that, advise, based on personal observations. Because our water is different to start with, we use different plants and animals and have different lighting, schedules and even have species of algae, our experiences can vary considerably. Using your own personal observations, knowing the options available and being willing to experiment are key factors in controlling hair algae in the aquarium.

Welcome to the Jungle | Into The Forest | The Creepy Crawlies | A Clearing in the Thicket | Algae Eaters for the Planted Aquarium
North American Natives | Why things go wrong Pt 1 | Why things go wrong Pt 2 (Algae) | Algae Eating Shrimp | Lo-Tech Tanks
Welcome to the Fish Room | The Stemmed Plants | Mosses | A Livebearer Biotope | Planted Tank Social | The Genus Hygrophila | Cyanobacteria
Easy Plants | What I Did Last Summer | Decorations in the Planted Tank | Botany-An Introduction to Plant Biology | Botany-Anatomy of a plant
Botany-How Plants Work | Easy Rosettes | Going High-Tech | Floating Plants | Dealing with Success | Bringing the Outside In | Vallisneria
Hair Algae | Flowering Aquarium Plants Part 1 | Flowering Aquarium Plants Part 2 | Liverworts in the Aquarium | Elements of Design
Planted Aquarium Maintenance | More Mosses | Invaders | Ferns in the Aquarium | Setting up a Planted Aquarium
Seaweeds of the Pacific Northwest | Proserpinaca | Hardware for the Planted Aquarium | Rotala | Neocaridina Shrimp | Lo-tech Tank Tips

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