How To Clean A Freshwater Fish Tank/Aquarium (Easy Guides)

The most common questions on the internet from aquarists around the world are about cleaning aquarium or fish tank.

Whether it’s to clean or remove algae from the fish tank, cleaning aquarium decorations, cleaning aquarium gravel, changing the water of a fish tank, cleaning fish tank glasses, and many more are part of the Clearing a fish tank or aquarium.

So, we have decided to create an article about “How To Clean A Freshwater Fish Tank/ How To Clean An Aquarium,” and we will be providing all the related queries and questions regarding this topic. And will keep a link to this main article.

Consequently, you will find all the related information in a single place, or you will know where to look for that particular information about your aquarium/fish tank cleaning. However, it’ll take some time to aggregate all the information. Until then, please support us.

As a fellow aquarist, I know how annoying to find the exact information in the time of need. So, you can keep this page as a bookmark to find easily for the next time.

Now let’s start our main conversation about our precious freshwater fish tank.

How to Clean a Fish Tank

The basic common steps for cleaning almost every fish tank or aquarium are kind of similar.  So, the best way to clean a fish tank (without cleaning them): step by step– (if you’re in a hurry)

  • Prepare the new tank water before starting the cleaning process. Let it adjust for sometimes (Fill the bucket with fresh tap water, use a thermometer to adjust the water temperature.                                                                                                                                                         Apply water conditioner, and aquarium salt according to the given instructions on the bottle. Add some bacteria supplement, if your fish tank is less than 4 months. Let the salt and other chemicals dissolve completely into the water).
  • Unplug the filter and heater; also, the air plug, if you have one.
  • Remove some water by using a siphon or something need to transfer the water.
  • Fish tank decorations and artificial plants, if the tank has; remove them all from the tank.
  • Start cleaning the inner side of your tank. Use different available tools to cleaning the inside; either purchase them from the market or make something from home to do the job.
  • Use a siphon or any other equipment to reduce the water level around 25%. Using siphon will help you to get rid of dirt or debris from the bottom of your tank.
  • Carefully scrub and clean all the ornamental features that reside inside the tank, including all the artificial plants, toys, and the filter.
  • Return all the equipment to its old setup. Don’t change the aquarium setup drastically without any necessity; it can create stress or shock to the fish.
  • Fill the aquarium slowly with the prepared water at the beginning.
  • Then, connect the power source.
  • For better result, keep the lights off for few hours after cleaning your tank.

Well, “how to clean an aquarium” answer to this question also depends on several other things. Like-

  • How big your fish tank is
  • Whether it’s a new or old one
  • Saltwater tank or Freshwater Tank

And many more, we will discuss all these questions consecutively. First, let’s discuss the Freshwater Fish Tank Cleaning elaborately below. This is a step-by-step guideline, so you don’t need to worry even if you’re asking how to clean a fish tank for beginners? Or, how to clean a fish tank without killing the fish? This is also your answer.

How to Clean a Freshwater Fish Tank? 

Now I will guide you step by step -how to clean a freshwater fish tank. Even if you are a noob or a beginner aquarist, if you follow our guidelines and adjust the situations according to you, you shouldn’t have any problem cleaning your aquarium.

1. Get the Supplies:

First thing you need to do is getting all cleaning supplies. There’re things you need to have before start cleaning your freshwater fish tank. However, all of these will be needed in your aquarium cleaning. Make sure you have everything we have mentioned here-

  • A Bucket or Two (Size should be according to your requirement) which you should use only for the aquarium cleaning purpose.
  • A Siphon Vacuum/ Gravel Vacuum
  • Algae Scrapper/ Algae Pad
  • Razor Blade (For acrylic tanks, please use plastic blade)
  • Chlorine Remover (Also known as Water Conditioner)
  • Bleach
  • Aquarium Glass Cleaner, or Lime Remover for Aquariums
  • Clean Old Bath Towel
  • Filter Brush
  • Paper Towels
  • Filter Media
  • A soft and clean brush

Run through this checklist before starting the cleaning process. After gathering all of these, you can proceed to the next step to clean up the fish tank.

2. Prepare the New Water

Before starting the fish tank cleaning process, you should prepare the new water for your aquarium. As the water needs, some time settle down and adjust with the current water temperature.

How to prepare fish tank water?

Take some water (Amount of water should be as much water you want to change) into the bucket from the tap. Check the water temperature, and adjust the temperature level according to your fish. You can use some cold or hot water to revamp the targeted water temperature.

Use water conditioner to neutralize Chlorine and other harmful metals from the water. Confirm the pH level is achieved. Then leave the water sometimes for everything to settle down to the desired condition.

Now let’s talk about some common questions regarding preparing the fish tank water. Before that, if you are Changing the Betta Fish Tank Water, Click Here.

Can You Use Tap Water for Freshwater Tank?

Yes, of course. Using tap water for fish tank is also suggested and best to use as long as you use the water conditioner to adjust. However, if you’re not using water conditioner to the water, let the water to sit (Two to Four Days) for some times before adding into the fish tank.

Can You Use Distilled Water in Freshwater Fish Tank? Or, Purified Water for Freshwater Fish?

No, you shouldn’t. Distilled or purified water removes all the minerals, nutrients, and important chemicals, which are necessary for the fish; so, it does no good for the fish.

Can I Use Bottled Water for My Fish Tank?

It’s not a good idea to fill your tank with bottled drinking water, as it’s a little expensive. But you can use bottled water for your fish tank if it’s not sparkling water.

Well water, Springwater or Filtered water is useable for your fish tank. Hence, you should check the water condition before adding to your fish tank. If the water lacks in any necessary minerals or has some harmful minerals for your fish, adjust accordingly.

Can I use Spring Water for Fish Tank?

Yes, you can. Springwater is a good choice for your fish tank if you need lower pH and hardness for your fish tank.

Is spring water good for fish?

Springwater has a stable temperature and comes with some necessary nutrients and inorganic ions. Although distilled or R/O (Reverse Osmosis) water doesn’t have the essential minerals to stabilize the pH level. So, beware the amount of spring water adding to your fish tank.

How Much Water Conditioner Per Gallon for Fish Tank?

Usually, 1 drop of water conditioner for per gallon of water, and 1 millilitre = 20 drops; hence, if the conditioner stated to use 1 ml. for 20 gallons, use 1 drop for every gallon of water. However, every water conditioner has their mixer, and have clear instruction mentioned on the bottle.

You will find the detail guidelines, which chemicals are included, amount of use, and other necessary directions for using that conditioner.

That being said, we can assume the water conditioner for per gallon of water:

1 Gallon Fish Tank = 1 Drop Conditioner

5 Gallon Fish Tank = Use 5 Drops Water Conditioner

For 10 Gallon Fish Tank = Use around 10 Drops

For 20 Gallon Fish Tank = 1 Milliliter or 20 Drops

So, follow this sequence to mix your water conditioner into the new fish tank water.

Do I Have to Put Bacteria Drops After Using Conditioner in a Freshwater Tank?

Most of the water conditioner has the necessary amount of bacteria in it. Also, as the days pass, your tank water and filter will grow the required bacteria. But, if your conditioner doesn’t have those essential bacteria, you can use some bacteria drops in your tank after using the conditioner.

What is the safe pH level for fish?

6.8 to 7.6. Since the 7.0 pH level is considered neutral, o and 14 are the lowest and the highest pH level consecutively.

The best pH level for the freshwater fish is around 7.0. Not too low or high than this. However, the pH level of a fish tank drops over time. To prevent the lower pH level of your Fishtank, do the regular water change partially.

Fish Tank pH Level Chart:

Fish Tank pH level Chart



3. Remove some water

Use the siphon hose or any other tools to remove some old water from your fish tank. Don’t transfer too much in this step because the water will also help you clean inside the tank.

During these cleaning process, do the work slowly and gently. Don’t scare the fish; it may even cause death to them. So, your main target, cleaning fish tank without killing them won’t be successful. Also, without fish, what you gonna do with a clean tank!


4. Cleaning Inside the Glass

Start the cleaning process inside the fish tank by using an algae pad. Try to purchase the pad from the pet stores. For hard and stubborn residue on the glass, use the razor blade to scrape it off.

Acrylic aquarium can get scratched by the razor blade. For an Acrylic aquarium, use a plastic razor blade instead.  Also, be careful not to hurt yourself.

Use pad and pad as necessary while scrubbing the aquarium glass from inside. Don’t use tools from other works to do the job.

You can perform this step before removing some water from your fish tank. Actually, I suggest you not to do so. Since it’ll be easy for scrubbing and cleaning after having less water in the tank, tank water won’t spill out easily during the cleaning.

5. Cleaning the Decorations

In the fifth step, clean all of your fish tank decorations. So, how to clean aquarium decorations? Or the best way to clean aquarium decorations:

  • Take out the aquarium or fish tank decorations.
  • Put them into a clean and soap-free sink or bucket.
  • Use an aquarium sponge to clean the built-up algae on the decorations.
  • Use the soft and clean brush (Toothbrush) to scrub the tight spots on the decorations.
  • Rinse them thoroughly.
  • If the decorations have perforations, then let them dry first.
  • Return the decorations into the tank.


How to clean aquarium decorations with vinegar?

Soak the decorations into the vinegar-water solution, and left them for around 10 minutes before rinsing them thoroughly. The ration should be 1:1 of water and vinegar.

How to clean aquarium decorations with Bleach?

You can also use bleach to clean your aquarium decorations. Soak the decorations into a bucket with 59 ml or 14 cup bleach for around 15 to 20 minutes. Rinse them thoroughly and wash them with water conditioner before putting them back.

Read: Cleaning Fish Tank with Vinegar


6. Clean the Aquarium Gravel:

Next, clean the gravel of the tank. Use a water siphon for normal cleaning.

So, how to clean aquarium gravel?

The best way to clean fish tank’s gravel- put the gravels into a bucket; then, take a garden hose and place them into the bucket with turning the faucet at full speed. Repeat the process as long as the gravel become clean.

But if you don’t have a garden hose, or you don’t want to remove them from the tank; then use the siphon to vacuum away debris, fish waste, excess food and dirt from the gravel. Ensure the vacuum process on every part of the fish tank.

Clean around 30% gravel each month. If your aquarium has sand substrate, reduce the water flow by putting a finger or kinking. Then use the siphon at some distance from the sand that won’t disturb the sand.

7. Remove or Transfer the Targeted Amount of Old Water

Since we have almost completed inside cleaning, remove the necessary or targeted water from the tank by using a water siphon or any other tools. While cleaning the aquarium gravel, this step can be performed together.

If you are using a siphon to transfer the water, be careful not to disrupt the aquarium setup and suck up the sand substrate from the aquarium. Move around the tank’s equipment slowly. That should do the work.

8. Return All the Tank Equipment Back

Here you put back the decorations, gravel or toys into your fish tank. Do this step gently and carefully, and you don’t want to distort inside the aquarium setup and create stress to the fish.

While putting back the tank’s equipment, check again everything is clean. If anything seems unclear or needs some scrubbing, do it again and put back into the tank.

If you are not planning to change the old setup, do it slowly. Any drastic change can out stress on your fish, remember that.

9. Fill the tank with new water (Prepared before)

Now slowly and gently fill up the tank with the new water, which you have prepared at the 2nd step. You can either use siphon hose or any other clean tools for transferring new water into the tank.

Before adding the new water, you should check the temperature level of both old water and the new, and make the required adjustment accordingly. Also, don’t overfill your tank.

Hasten water transfer could disrupt your tank setup and scare the fish.

10. Observe the Water

In this step, let the water settle down and become clear. The water will become clear soon. If the water doesn’t get clear, try to find the reason behind it whether your new water was cloudy or not.

There’s water clearing agent in the market, but you don’t need to use them. If the water doesn’t become clear itself, find out the reason and fix it.

If you see the water become clear, then move to the outer exterior cleaning part. Until confirming inside cleaning, don’t start outside cleaning work. Also, you could wait a few minutes and take a little rest before the glass and exterior cleaning.

11. Clean the Outside Glass and Exterior

Once the inside is clean and fresh, you can now start cleaning the outside glass and other exterior equipment like a light, hood, tank top, etc.

Use vinegar or aquarium glass cleaner to clean the outside glass. Spray the liquid on the glass, then hold the top side of the fish tank with one hand and use the other hand to wipe the glass by a clean damp cloth or towel. It’s best to use soft cloth for this job.

12. Clean the Filter about a Week later

Leave the filter as it is for now after a week or two clean your aquarium filter. Instant filter cleaning along with all the other equipment can cause disrupt the fish tank environment. So, cleaning the filter after a week is the best thing to do.

Once your cleaning is complete, just set the filter without cleaning. After a week later, remove the filter and it thoroughly. Then set it carefully as it was before.


Since we talked about a lot of things in between the cleaning steps, you may find it difficult to distinguish them. So, let’s have another look or summarize on all the steps in a single place- How to clean a dirty/unclean fish tank?

  1. Get the Supplies
  2. Prepare the New Water
  3. Remove some water
  4. Cleaning Inside the Glass
  5. Cleaning the Decorations
  6. Clean the Aquarium Gravel
  7. Remove or Transfer the Targeted Amount of Old Water
  8. Return All the Tank Equipment Back
  9. Fill the tank with new water (Prepared before)
  10. Observe the Water
  11. Clean the Outside Glass and Exterior
  12. Clean The Filter After A Week Later


Frequently Asked Questions (F. A. Qs)

How Often Should I Clean My Freshwater Fish Tank?

Depending on how many fish you have, the size of your tank, and also how you have it stocked, this could be anywhere once in every two weeks (3-14 days).

You need to change around 30% water on a regular basis, and supplement it with new and clean, dechlorinated water.

Suppose, you have a basic 10-gallon fish tank, with few fish in it and decorations. It would be best if you were replacing around 3 gallons of water per week.

You will need to use a gravel siphon, which is basically a hose with a tube at the end, to loosen up the gravel at the bottom and remove the waste and debris that has settled in there. This is where you need to worry about the most.

If all you do is scoop some water out of the top of the tank and replace it, all the junk at the bottom (like uneaten fish food) will continue to sit there and rot.

Should I remove fish when cleaning tank?

No, you should leave the fish as it is in the tank and do your cleaning process gently, as long as it’s a partial water change or cleaning. However, if you are planning to full water change, transfer the fish into the new prepared water before start cleaning using a fishnet.

During the partial water change, there will be plenty of water available in the tank for the fish, so don’t take it out, that will create stress to the fish. Catching will give them the highest stress level, hence avoid it.

So, can you clean a fish tank with fish in it?

Yes, you can as long as you are doing a partial water change and cleaning. Removing fish from the tank isn’t a good idea. So, leave the fish in the tank, unless it becomes necessary to remove it.

How do you remove fish poop from aquarium?

During gravel cleaning with a water siphon hose, fish poop will be sucked up. You just need to give some extra concentration while cleaning. It will also remove uneaten fish food, dirt, dead plant bits, shed scales, and other debris from the of your tank.

So, you don’t have to do extra work to remove fish poop from the tank.

Why did my fish die after I cleaned the tank?

The main reason is stress; during the cleaning or water changing process, fish went through a lot of stress, also after cleaning your tank, the water condition or environment they used to changes, this sudden change sometimes hard for the fish to tolerate.

So, these are the two common causes of why your fish die after cleaning.


Final Words

Cleaning your fish tank require time and sincerity. If you don’t have that dedication, you shouldn’t bother to have a fish tank yourself.

But if you are willing to put that effort and dedication, cleaning a fish tank shouldn’t be a problem for you.

And we are here to help you with your journey to keep a clean and healthy aquarium if you follow our guidelines and adjust to your own situation, you know- how to clean a freshwater fish tank without any problem.

The basics are the same for almost all types of fish tank, some special case and situation just need some adjustment, then you are good to go.

So, that’s all for today, until next time, keep your fish tank clean and take.

Now, there’s something we would like to hear from you:


Which Step among all the cleaning process is most important?

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