Hair algae in the planted aquarium - How to get rid of it and keep it from coming back

Hair algae AKA filamentous algae is unfortunately all too common in the planted tank. Even though it can be a nuisance aesthetically, it's not bad for our fish. There are a couple algae eaters that nibble on hair algae, but no one will be able to wipe out an infestation. In a breeding tank, it provides excellent hiding spots for juvenile fish or microscopic critters that serve as a food source for fry or micro predator fish like dwarf gouramis and threadfin rainbows.

In today’s guide I’ll teach you how to identify hair algae, determine where it's coming from, show you how to get rid of it and keep it from coming back.

Rather watch a video? Check it out ⬆️

Appearance

Hair algae is pretty easy to identify. It can vary a bit in color and length, but is always fibrous. Some types of hair algae branch out from one stalk while others only form one branch. They can be extremely soft, or really tough. They can get really long and show up as a single strand, grow in little tufts and patches or create thick matts. In some cases, it’ll even have a unique odor when you pull it out of the tank, though that’s not super common.

I let things get really out of control in this tank - absolute hair algae infestation!

Causes

Obviously the first thing anyone will want to do, is to pull out all the hair algae. However, if you don’t figure out what’s causing hair algae to grow, daily manual removal can become a full time job!

As with other types of algae, whether or not you use CO2 will influence how you diagnose the source of your hair algae. In either case, low flow is a large contributor. High flow to moderate flow is important in combating hair algae because it prevents debris from settling on surfaces. Those debris will eventually start to rot and form the basis of algae growth. Flow is also important because it helps to distribute nutrients (and CO2 if you’re using it) to plants. Keeping your plants healthy is one of the best things you can do to deter any type of algae. Healthy leaves don’t allow algae to grow on them and outcompete algae, preventing it from growing on rocks and wood.

For tanks with CO2, it’s often the case that lights are cranked all the way up and CO2 levels are low. Even fluctuating levels of CO2 can trigger a hair algae bloom. So make sure to set your CO2 levels to an appropriate amount ~ 30 PPM and make sure it stays there. If that doesn’t solve the problem, then try lowering your lighting a bit.

For tanks without CO2, high lighting is the most common source. It’s pretty much a guarantee! Also consider the health of your plants. If they are struggling to grow and leaves are forming with holes in them, then chances are you need to address plant health issues as well.

Removal

The first step with any algae is to physically remove as much of it as possible. Fortunately hair algae is easy to grasp and rip off by hand - it doesn’t cling to surfaces like black beard. No matter how diligently you remove hair algae by hand, there will always be a few chunks remaining, and these of course have the potential to grow large again.

In cases of extreme infestation, you may need pull out hardscape and plants to spray them down with a three percent hydrogen peroxide solution. That’s a pretty typical concentration when you buy it at the supermarket. Simply put it in a spray bottle, and spray down objects. Let them sit for 15 minutes before rinsing off hydrogen peroxide. I like to stick plants in buckets with lids for the fifteen minute period so that they don’t dry out. For hardscape, you can let it sit as long as you want, but for live plants, be careful not to exceed fifteen minutes.

It’s a good idea to scrub rocks and wood down at this point to knock off any chunks of algae that you miss when pulling by hand.

Spraying plants with tons of hair algae and scrubbing off sticks and stones.

After waiting a couple days, I can see that most of the hair algae is dead! It’s turned kind of a pale, whitish color, but sometimes it will turn red when it dies. There might be a few little living sprigs left, but for the most part, mission accomplished. It’s best to pull out what remaining bits of hair algae remain, and for those that you can’t get completely pulled out, spot target with Seachem Excel or another liquid carbon.

Dead hair algae has turned almost completely white after a couple of days.

Prevention

OK, so you’ve done all this hard work to get rid of your hair algae. Now it’s time to take some steps to prevent it from coming back.

For CO2 and no CO2 tanks alike, keeping your plants healthy is one of the best ways to stave off hair algae ~ check out this video to learn more about plant care. In order to ensure that your filters are putting out a good turnover rate, make sure to give them a good clean out.

If you are running a no-CO2 tank, make sure to not blast your light on the highest setting, and keep it on for 8 hours a day. Whether it's built in, or you have to buy one, keeping your lights on an automatic timer is super convenient. It’s so hard to be consistent about manually turning lights off and on at the same time every day and it’s easy to forget to turn them off at night if you’ve had a long day.

Although it sounds counterproductive to use fertilizers to get rid of algae, a lean fertilization regiment can really help keep your plants healthy, and healthy plants do a good job of repelling algae from growing on them.

If you are running a CO2 tank, make sure to keep your levels at 30 PPM. You can also get away with using stronger light and fertilizing a little more if you use CO2. That’s because CO2 unlocks a higher potential in plants to consume more nutrients and light, making them grow faster and healthier - and I’ll say it again healthy plants are the best way to keep algae in general at bay!

Algae crew

Last but not least, a strong algae crew can help prevent hair algae outbreaks from ever occurring. They do this by eating biofilm, an organic layer in our aquarium that attracts algae. They also eat algae as it’s starting to grow, when it’s more palatable. Even though Amano shrimp and otocinclus will graze on small amounts of young hair algae, they will not eat mass quantities of it.

Blue bolt shrimp.

If you live in Norther Colorado and are having a hard time staying on top of your algae, feel free to reach out and schedule a cleaning or consultation! If you don’t like in the area, we also offer remote consultations.

That’s it for hair algae. Hopefully you found this article helpful. Drop a comment if you have any questions or enjoyed the article!