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How To Easily Remove Algae

Updated: Sep 22, 2022

Do you have persistent algae that just won’t go away?

This article explains the easy steps to instantly neutralize any pesky algae growing on plants, fixtures, ornaments, rocks, and wood. The time involved will depend on the size of the tank and the number of items you want to remove algae from, but, in general, for an average-sized aquarium in the 30–75-gallon range, it should take no more than an hour of your time (and even likely less!).

For clarity’s sake, this may at first sound like a “magic solution” to any and all algae problems, but let’s dispel that false narrative quickly. While we may be able to easily remove the algae from items, the conditions in the water that led to the growth of the algae are the source of the problem.

If you break a leg and go to the doctor, the doctor won’t just give you pain medication and send you home. The doctor will analyze the leg, understand how it broke, and develop a prognosis to remedy the broken leg. Fixing your algae problem is much the same.

This treatment guide is like giving your aquarium pain meds and sending it home. The cause of that pain (algae) must be diagnosed, and a prognosis must be made to correct the conditions that led to the algae growth. The ideal situation for applying the steps below is after you’ve fixed the source of the algae growth and now want to remove existing algae from items in your tank. You can instantly improve the appearance of your aquarium by removing gross algae.

The critical component of this treatment process involves chlorine bleach, also known as sodium hypochlorite, which is toxic and lethal to aquatic life. Bleach or a bleach solution must never be used in a living aquarium or anywhere near live fish (not even the aquarium’s glass for fear of cross-contamination).

Where can bleach be used? Use it on live plants, fixtures, ornaments, rocks, and wood that has been removed from the tank. The key point is that these items must be entirely removed from the tank before being treated. Do not use bleach or a bleach solution in a live tank. Once safely removed, all items can be treated, thoroughly rinsed, and then safely returned to a live tank with no adverse effects on the fish, the filtration systems, or aquatic balance.

Follow the steps below:

Step 1: Get bleach.

In my experience, bleach is sold in every supermarket, so if you don’t have some at home, you can easily pick it up at a local store. I encourage you to spend a little extra and get name-brand quality bleach like Clorox. Different styles of bleach serve different purposes, so get a regular concentrate (8%) or performance concentrate (8.5-9.5%) formula.

The key ingredient you are looking for is sodium hypochlorite. Variations like “color safe” or “splash-less” are often made without the necessary ingredients to serve our algae-removing purpose. In the end, you get what you pay for, and if you care as much as I do about my tank, I don’t mind spending a few extra bucks to ensure it’s done correctly.

Additionally, bleach does have a shelf-life, so if you’re planning on using that bleach container that’s been sitting in your closet for the last five years, I’d toss it and get a new one. The chlorine in the bleach will diffuse (even sealed) over time, and the effectiveness of the bleach becomes severely diminished.

Step 2: Ready your workspace.

We’re using bleach. Bleach stains. It discolors, and it will even eat away and disintegrate some fabrics. Be mindful of what you wear (wear clothes you don’t care about) and where you work with the bleach. The bleach will splash on your clothes and the surrounding area, which will cause stains.

Included in your workspace and clothes are the tools you will need. This will depend on the size of your aquarium and the items you’re disinfecting, but generally, you’ll need:

  • 3–5-gallon plastic bucket.

  • Measuring tools like a cooking cup or teaspoon.

  • Something to mix the solution, like a large pasta spoon (or fish net).

  • Gloves (like dishwasher gloves).

  • Bleach Concentrate

  • De-Chlorinator Mix (optional)**

**Make sure to grab an extra bucket if you want to use the de-chlorinator solution after you treat the items.

Step 3: Create your treatment solution.

The bleach solution is simple and easy to make. You want to aim for 1/3 cup of bleach for every gallon of water. For a three-gallon bucket of water, you add one cup of bleach. For a four-gallon bucket of water, you add one cup and 1/3 cup of bleach. For a five-gallon bucket of water, you add one cup and 2/3 cup of bleach.

If you overdo it on bleach and your solution is too concentrated, you risk damaging your aquarium items. You want to ensure you don’t over a 20% solution of bleach to water (this is high and unnecessary). Ideally, you want to use warm water. Do not use water that is steaming or boiling in any way. This is important because bleach is toxic, and you do not want to breathe in fumes. Warm tap water is good enough. Do not boil the water.

  • 1/3 cup per gallon of water.

    • 3 Gallon Bucket? Add 1 Cup of Bleach.

    • 4 Gallon Bucket? Add 1 & 1/3 Cups of Bleach.

    • 5 Gallon Bucket? Add 1 & 2/3 Cups of Bleach.

  • Use warm water (not boiling or steaming; fumes are toxic).

Step 4: Choose items to clean.

Choose which items you want to remove algae from and safely remove them from the tank. I advise against removing plants directly planted into the substrate as the roots are delicate, and you risk killing the plant. If you can safely remove the plant without disturbing the aquarium or killing the plant, then, by all means, remove it and prepare it for the solution. If you’ve glued plants onto objects that can safely be removed from the aquarium, then take those out together but avoid using the bleach near the roots of the plants as they are generally more delicate.

Go ahead and rinse off anything you can get off with water, and don’t bother scraping or brushing items. A lot of organic matter, like fish food or rotting plants, will quickly wash away with water. We want to ensure our bleach targets the algae below the organic matter. Once you’ve rinsed them off, set them off to the side until you’ve removed all the items you want to remove algae from.

Step 5: Place items in the bleach solution.

One by one, place the items in the bleach solution and fully submerge them below the solution’s surface. The most important part of this step is timing. Use the chart to ensure you don’t keep items in the bleach solution too long. Too much exposure to the bleach solution will kill plants, stain items, and even destroy some decorations.

Step 6: Allow time to pass and remove items.

Once the recommended time has passed, remove the items from the bleach solution. I suggest immediately rinsing each item as you remove it from the bleach solution. Warm water is one of the best ways to remove the bleach solution. However, if you want to be one hundred percent sure you don’t have any lingering bleach on your items, you can place the items in a de-chlorinator solution. Many aquarium stores carry de-chlorinator treatment for treating tap water. Generally, it’s cheap and easy to find, but water will work just fine.

Step 7: Return items to the tank.

You can now safely return the items to your tank. The algae may still be present on some things, but this is expected. The bleach solution killed the algae, and over the next 24-48 hours, all the treated items will lose all the algae. All algae is different, and there are thousands, if not more, types of algae so the process will differ. Some will turn red. Some will turn white - some black or brown. This is normal. Your filter will naturally remove it from the tank after it dies off and disperses. Some algae will disintegrate within minutes. There are many variables, and it’s impossible to know precisely what algae you may have or how it will react, but it will certainly disappear.

Conclusion and Remedial Action

If, after a few days, the algae is still present on items, I would check the bleach you used. Is it old? Does it have a high enough concentration? It might not have enough potency to kill the algae as intended. Did you submerge the items for the recommended time? The algae may not have been exposed long enough to the bleach. Did you clean off all the organic matter covering any potential algae? These are a few questions to ask yourself if you have lingering algae after a few days. We’re always here to help, so if you have any questions or issues, drop them in the comments below, and we’ll get back to you soon.

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