Filtration – Keep Your Fish Tank Clean Your Fish Need It

It may seem like a very basic concept, but keeping your fish tank clean is one of the most important things you can do for your fish. Good filtration is key.  It’s right up there with getting them food and keeping them in water!

What are the repercussions of letting your tank get filthy? There are many. We are going to explore how to keep your tank clean, what happens when you don’t keep it clean, and highlight some basic water ecosystem knowledge along the way.

Sit back, grab a cup of joe, and get ready for a thank you card from your fishy friends. They want you to read this article. They also want a new plant in their tank!  If you haven’t even set up your tank yet then check out our starters guide here….. Easy Steps to Setting Up Your Own Aquarium.

Duh, a Clean Tank, but How?

There are so many components to keeping your fish happy in a well maintained tank. You aren’t new to this planet so you probably realize by now you have to keep your fish tank clean if you want your fish to live, right? Good. We are on the same page then!

Let’s figure out just what you need to keep your tank happy and healthy for your favorite little aquatic buddies. It’s not overwhelming if we can breakdown the main points and explain the why behind the duties.

Ammonia Stress

Stress? Your fish have stress? They just float around all day and make bubbles. That sounds like a very stress free, albeit boring, life to me.  Yes, it’s true, fish can get stressed too. However, it’s almost directly related to their environment and nothing else.

Ammonia stress is when your fish begin to have a negative reaction to a build-up of ammonia in your tank. This can happen gradually or really fast depending on how small an environment you have. If you have a small tank, you are going to see a rapid succession of symptoms before you hit full on ammonia poisoning.

Ammonia buildup is related to waste from fish and not enough oxygen in the water.  Essentially, you are suffocating your fish. The symptoms range from mild (general lethargy from your fish), moderate (gasping for air at the surface of your tank), and finally, severe (inflamed eyes).  These are all still classified under ammonia stress and can be resolved if you act quickly.  However, if you are paying attention to your tank, you will notice the more mild symptoms and act accordingly before it gets out of hand.

What to do when you notice ammonia build up in your tank?

If you do notice an ammonia issue, you must act quickly. It may be very tempting to go rush out and buy a bunch of chemicals to fix the problem. However, if you talk to any good tank owner, you know this isn’t the best solution. Some of the chemicals can have unwanted side effects on your fish. The other issue with this is the chance of error in amounts you pour in. You could easily kill your fish if you aren’t using the proper amount.

The fastest and safest way to remove ammonia from your tank is to do a water change. A water change can be done quickly and will effectively start helping with ammonia build up. It allows the biological filtration process to do what it does best: filter! Your fresh water is going to be ammonia free. Granted, you must take proper steps before just dumping some fresh water into your tank from your sink.

You need to make sure this new water is properly treated and at the same temperature as your tank water. It’s better to take a portion of the old water out and replace it with a small portion of new water. Do this every week to keep ammonia from building up in the first place.

If your problem is borderline severe ammonia stress for your fish, you may want to do a full tank clean. Deep clean your tank by using a gravel vacuum, scrubbing down the glass, scrubbing up all of your plants, castles, etc., renewing cartridges in your filter, and of course, getting all new pre-treated water in your tank.  Acclimate your fish properly so they do not have a severe temperature or water shock.

If you have a fish death, you have reached ammonia poisoning and have a bigger situation on your hands.

Ammonia Poisoning

Ammonia poisoning is very similar to ammonia stress, but it’s reached the level of fish death. If you have one or more fish pass away, it’s most likely ammonia poisoning. While this is a sad situation, you can still save your remaining fish if you act very quickly.

I would recommend first getting a bucket or bowl of water properly treated and temperature acclimated for your fish. Get your fish in that new water as soon as possible. Then, it’s time to get to work on your tank.

You are going to want to clean everything. That ammonia level has reached a point of no return and you will need to start new with your biological filter system. Clean everything and I mean everything. You even need to take your mechanical filter out and clean that. Replace the cartridges in it while you are at it.

Scrub down all of your plants and features in your tank thoroughly.  Do NOT use any household cleaners on it because that can be just as toxic for your fish.  Just clean thoroughly with warm water. I would also suggest buying new gravel or sand if you don’t feel like thoroughly cleaning that.

Next, get some fresh water back in your tank and start running the filter immediately. You want to get aeration in the water and get some biological factors going in your tank to get that good bacteria back in control. Once you feel confident your tank is clean and your water is ready for your fish, put them in and watch them carefully.

What Causes Ammonia Stress and Ammonia Poisoning?

The most common cause of these is just not cleaning your tank properly. Other possible reason for ammonia build up can be too small of a filter. If you have done both of these it’s time to look at some other issues that can arise in your tank.

Do you have the right ratio of fish to tank size? This is an important step when starting a tank and often overlooked. Another issue can be overfeeding these fishy friends. If you do, there can be excess waste which translates to too much ammonia.

Proper Filtration is Key

Filtration is often a 3-party system in a fish tank: biological, chemical, and mechanical. The most important of all of these is the biological portion. It is the basis for your tank. The biological filtration, in essence, is the balance of good bacteria in your tank with oxygen. If this gets out of whack, you are in big trouble.

Chemical filtration is optional in a lot of cases. Most of the time it is unnecessary but if it is needed, you are probably going to use an activated charcoal. This can eliminate any toxins in your tank and quickly. Chemical filters are often used in worst case scenario cases or if your fish need medication to be removed from their water.

Mechanical filtration is the most well known form of filtration in a tank. You probably planned or have already bought a filter for your tank. This is going to do a clean sweep of your tank and remove the debris, gently aerate the water, and help keep the nasty ammonia and nitrites at bay. We’ll get more into that later, and you can read our nitrates can kill article here.

As you can see, filtration is a huge part of keeping your tank clean. If you want to know more about filtration in your fish tank, check out my article on it by clicking here.

Water Changes Are Vital

I’m betting you wouldn’t drink a glass of water that has been sitting out for a week or two in your house. You can also bet that your fish won’t like that either. Changing the water in your tank is vital to keeping your fish happy and the water from accumulating too much ammonia or nitrites.

How to do a water change and how often?

Water changes don’t have to be complex or frustrating procedures. You can simply take out about ¼ of the water in your tank using a siphon and then replace it with fresh water. Make sure your new water is at the same or similar temperature to your tank water, it has sat out for a little while, and doesn’t have any other components added to it.  Another consideration is ensuring that the water retains or matches the desired pH levels, has the same water hardness (GH or dH levels) and also the carbonate hardness (KH) is maintained.  For more information on this see our article ‘Water Hardness Matters – Chemistry Made Easy’

How often should you do that? Well, if you do it weekly, you won’t have to clean your tank nearly as often. I would say that would boil your deep cleaning of your tank down to about once a month. That’s not so bad!

Aeration is Essential

Even though your fish friends live in water, they still need plenty of oxygen. Getting an aerator is an easy way to accomplish that. A lot of mechanical filters will have one built in but read up on it to make sure it is enough aeration for your number of fish and tank size.

Aeration has another purpose besides providing more oxygen in the water. It actually stirs up or agitates the water in your tank. What in the world does that have to do with keeping your tank clean? A lot actually!

Stirring up your tank allows you to get a lot of the debris swept out of the rocks or gravel and into your filter. Think of it as a mixer on an extremely low speed. It’s going to gather up everything and distribute it evenly. This allows your mechanical filter to work at optimal levels.

Keep Algae At Bay

Algae is not only unsightly in a beautiful tank but it can cause some issues for your fish as well. If you get an overgrowth of algae, you are going to throw your biological and chemical balance off in your tank.  Not to mention, you are going to make your mechanical filter work on overtime.

An easy way to keep algae overgrowth away is getting a magnetic scrubber. These are even a little entertaining if you are into zen and all of that. It will help keep it from adhering to the sides of your tank.

Another obvious way to keep that algae away is to clean your tank regularly. I think once a month is okay as long as you keep up with weekly minor cleaning like a magnetic scrubber and changing out water partially.

Correct Tank Size to Fish Ratio

This is a big one in keeping your tank clean, folks. Obviously, if you have too many fish for your tank size, the water is going to get murky awfully fast. Just think, extra food, extra waste, extra CO2, extra bacteria, the list goes on and on.

Make sure you read up carefully on your fish before purchasing them. How big of a tank do they need? Another thing to consider is looking into your tanks size vs. mechanical filter capability. If you get a filter that is for a smaller tank, you are going to run into a toxin build up really fast.

It’s better to have a tank that’s a little too big, a filter that’s a little more power than you need, and less fish than any of the opposites. You don’t want your fish unhappy or unhealthy in their tank. What’s the point in that?


Keeping ammonia stress at bay doesn’t have to be super complicated. There are some easy steps to take to make sure you don’t have ammonia stress in the first place like: proper filter size, proper tank size, cleaning weekly, deep cleaning monthly, water changes, algae control, proper feeding habits, and proper filtration.

For more information on the comparison of fish tank filters go here.

Finally, if you just keep an eye on your tank and the way your fish are acting, you will be able to detect any problems before they start. Your fish will be happy, you won’t have to be cleaning in a frenzy, and your tank will look majestic.

8 thoughts on “Filtration – Keep Your Fish Tank Clean Your Fish Need It”

  1. I would have never thought to just switch out 1/4 of the water at one time so you don’t have to change it as often. Thank you also for mentioning the other benefit to having an aerator for your tank, how it can get the stuff that’s stuck in the gravel to come apart.

  2. I’m glad you stressed the point that having a clean tank is as important as their food. Having a good aerator is key in my opinion too!

  3. It doesn’t seem too complicated to protect your fish from excess ammonia. I didn’t know people actually use activated charcoal in the tank!

  4. I’ve been to some restaurants and seen their tanks, horrible, dirty, sometimes cloudy water… wanted to go back there and clean the tank myself!!

  5. I’d never just dumb chemicals in there to clean the water of extra ammonia, I’d just get rid of the water and start new.

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