Hair Algae


Jan 23, 2005
Hi tom, what is the best way to fight it in a healthy well growing tank? everything seems to grow well, but among the glosso and the wallichi there are clumps of long ugly green hairs.
ph 6.7-6.8
kh 5
no3 30
po4 0.8-1.0
good amounts of K and FE
light 10 hours of 1W/L

Tom Barr

Staff member
Jan 23, 2005
Re: Hair Algae

Did you see the hair algae thread I added?

Tom Barr

Hair algae tends to bug folks more than others, good nutrients alone often cannot eradicate it.
But good nutrients can prevent it from infesting your tank.
The problem: how to get rid of what's there.

Sterile technique: Dip everything in H2O2/Bleach etc, prevent any water, fish waste from allowing any spores into the tank.
Once the algae does make it past this line of defense:

Rapid response:
This is where many fail, they hope it'll just go away. Seldom does that occur. Many think it'll be taken care 5 days from now when they do a water change, that typically works. But if you see algae, that means something else is wrong, something that affects plant growth. Algae will respond first to these changes.

Neglected tank with bad infestation:
Okay, so you have slacked off, now you have a nice infestation. Hair algae that infest gravel pieces: rotate the gravel's top 1" under, no light, no growth, bury the algae alive(think cheesy horror film). This is fairly easy.
Plants: prune the stuff off, pick and preen. If this is bothersome, remember the rapid response next time, it's easier to deal with a small patch rather than ignoring a problem and hoping it goes away. Uproots the plants and give them a good inspection, work each section of the tank, perhaps 1/4 to 1/2 of the bottom surface at a time each week, after a couple of three weeks, algae will be gone. Adding good nutrients during that time will select for the plants even further.
Pull up everything from those sections, clean it. Clean the filter, net out any dead leaves, fluff the plants, and any dirt that's around the tank after you are done trimming. Get everything out of there. Clean your equipment,driftwood and rocks. Bleach and H2O2 are good for this. H2O2 on wood, the rest: bleach.
Add some Amano shrimps etc.

Now if you remove all the algae or most of it, then you add good nutrients, after a few repeats of this, algae will not do very well no matter what.
You have totally reduce the biomass of algae, increased the ability of the plants to grow and be healthy, removed the algae from surfaces, only young wimpy zoospores are left looking to grow on surfaces. They take a while to grow up into harder to eradicate adults, so by the next 3-4 days or week, you hit them again, they will die off and only very resistant seasonal spores will remain. These spores are not like the zoospores, they need a large change in the conditions to thrive and bloom/activate their growth.

Generally things like a decline in CO2 or O2 levels, increased light(with no increase in CO2/nutrients etc), NH4 and temperature.
Of course neglect helps these things occur in our tanks.

If you keep up on it, then things go well, if you do not want to keep up on it or find you don't... even if you want to, try less light, then if that's still not enough, go non CO2.

Hair algae is much like duckweed or other plant like weeds. Cladophora is a lot like a plant and is in Plantae: this species possesses: Chl a and b, starch as a storage product, same chloroplast type as vascular plants and pigments. Green spot algae and Chara are both green algae that are highly evolved and do well in most plant tanks. Hair algae is not far behind. Now what does air do to smaller algae that can live on less nutrients? It blocks the light below, same deal with plants, they out compete algae for light, so at lower lighting, the plants do very well. Rather than breaking the light cycle up, it's a question of competing for the light itself.
You can run a UV after a good pruning/cleaning, you can run a diatom, you can add Excel, you can add H2O2, you can add copper at lower doses(just like H2O2).
Once you get things settled and do this the following week, these are not needed. I don't need them and simply don't use them any longer. I know the tank will balance out and in favor of the plants.

Folks that have done reworks and tried this know things will be okay and you do not need to use other things other than pruning, water changes, good nutrient levels. It's the same old thing 1000 times.

time for me to go prune my neglected tanks at home.


Tom Barr