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Getting Rid of Algae in the Freshwater Aquarium

  • Marine Depot
  • Nov 13, 2020

The worst thing about running an aquarium is algae, and some fishkeepers even leave the hobby because of it. A clean, pristine prism of water can quickly become a green swamp, and once algae takes hold it is hard to get rid of. But don’t fret here are some tips on how to prevent or get rid of algae in the freshwater aquarium.

Lifegard Aquatics Nano Tank with Built-In Filter (8.3 Gallon) – CRYSTAL Elevated Low Iron Glass

Avoid Introducing It

This sounds obvious but avoid introducing any form of algae to your tank, as once it’s in there, it’s very hard to get rid of. Algae can be introduced on plants and can quickly transfer onto decor or into a mature filter, so only ever introduce plants that are free of algae, like tissue cultured. If it does find its way onto decor, the decor can be sterilized with bleach or dried out. If you have an old tank with a case of bad algae, don not transfer anything into the new one.

Scrape it Out

All tanks get algae, and the sparkling examples you see on Instagram are just cleaned more often or for the gram. Use a scraper on the inside glass daily to keep it algae free and prevent any build-up. An algae magnet to scrub algae while keeping your hands dry and if you do it little and often, just like any chores around the home, it prevents algae from growing into bigger, tougher jobs.

Siphon it Out

Just before the next water change, give the algae thorough scrape. Use a siphon to suck out all the dislodged algae spores and detritus that would go on to fertilize the next algae growth. Regular water changes are key to keeping algae in check, as it is physically being removed from the system each time. 

Magnetic algae cleaner and siphon cleaning out algae
Mag-Float Magnetic Algae Cleaner

Starve it Out

Algae thrive on spare nutrients that build up as byproducts in the water. Use nitrate and phosphate removers to soak up these algae fertilizers and remove them from the water. Algae uses ammonia too, so use a large biological filter to tightly cycle any ammonia as soon as the fish produce it. If your tap water contains fertilizers switch to reverse osmosis water for a purer source.

Naturally Graze it Out Fish to help get rid of freshwater algae

Mother nature can help out with your algae battle in the form of algae-eating fish and invertebrates. Add a pleco, algae-eating loaches, even Mollies, and all will graze algae all day long, reaching all those little spots that you can’t. Small freshwater shrimp also work day and night to eat algae and polish every grain of gravel in the tank. They pay themselves off in free labor by helping you stay on top of it. Add an army of algae eaters of all kinds and you’ll notice the difference.

Deprive it of Light

A blackout can work as a last resort for bad algae manifestations as algae can survive many scenarios, but can’t live without light. Turn the lights off and completely cover the aquarium for two days. Plants and fish will be fine but algae can’t cope without this vital energy source. Lighting can be cut down to just six hours per day afterward which should weaken it enough to gain control of the algae.

Give it Some CompetitionFreshwater plant to compete with nuisance algae

Live plants have been fighting algae for millions of years and can beat it in several ways. This time actually add nitrate, phosphate, and Potassium (NPK) to feed the plants so that they can grow is another method of how to get rid of freshwater algae. Rampant growth won’t let algae take hold and they can also overgrow it and shade it by covering the surface. They can emit natural algae fighting chemicals so give plants the right light, CO2, and fertilizer and they will fight algae for you, the natural way.

Kill it Off

In severe cases, algaecides can be used to get rid of algae in the freshwater aquarium, although they don’t address the root cause of the algae growth nor stop it from coming back in the future. They do, however, upset the equilibrium in the tank. Use algae treatments as directed but monitor the fish and make sure you add extra oxygen from an airstone. Remove any dead and dying algae from surfaces with a brush, and siphon it out and discard the water.

Zap it with UV

An ultraviolet sterilizer can be used to treat green water in an aquarium. Green water is tiny unicellular algae that float in the water and turns it into the color of pea soup. Connect a UV to your filter and algae that is exposed to the UV rays inside are damaged, causing them to clump together and die off.

Aqua UV sterilizer to kill free-floating algae in the aquarium

Filter It Out

Algae thrive on nutrient sources. Slime algae, like Cyanobacteria, start in the least disturbed area of the tank where dirt collects and flow is low to non-existent. Use a powerful filter and/or powerheads to increase circulation all around the tank, lifting dirt and keeping it in suspension for the filter to remove. Strong water flow can help to tear sheets algae from rocks and gravel too. So trap as much fish dirt and particles from the water as you can with a powerful filter, just be sure to clean out the filtration often. A clean aquarium suffers much less from nuisance algae than a dirty one.

Go All Out

Use three in combination or even all of the above measures of how to get rid of algae in your freshwater aquarium for good. Cut down lighting, introduce algae eaters, scrape algae, change out more water, upgrade the filtration, and plant heavily and you’ll not only beat it, you’ll stop it from coming back.

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