Common Problems With 100 Gallon Tanks

Although it’s nice to have your own private view of the underwater world, but it can be quite difficult to maintain it. As the adage says that all that glitters is not gold. Hence all the aquarium enthusiasts will be aware about the common problems that show up with large fish tanks and aquariums.

A small fish bowl does not require much effort from your end, except replacing the old water with fresh and similar tasks, but a large aquarium – a 100 gallon tank, will require a lot more. However, that does not mean that an aquarium does not offer you anything. You might be wondering that if there are so many efforts required to maintain it, why would people want to invest in one.

Here’s why:

Reasons Why People Like To Have An Aquarium

Some of the top reasons why people like to invest in a large fish tank or an aquarium are as follows.

  • Stress Relief
    It’s safe to say that you can say goodbye to all your stressors when you’re looking at the underwater world that will give you nothing but peace and serenity. This is one of the reasons why people have it in offices, hospitals and similar places. Even the cleaning process can be therapeutic and stress relieving.
  • Better Sleep Quality
    Since a large fish tank is a telltale way to say goodbye to your stressors, it can calm your mind which can help you sleep better at night. It gives your brain, the time to consolidate memory and build new connections. Watching it before you go to bed can help you sleep better.
  • Reduced Pain and Anxiety
    Since watching a fish tank or an aquarium is almost hypnotic, most people experience calmness which results in normalizing your blood pressure and heart rate. Even the noises of the aquarium, splashing of the water and the view can instantly calm you, which can be a good distraction from pain and anxiety.
  • Added Beauty and Aesthetic Appeal
    People like having one around because it makes the interior of a house, look more exquisite and high end. Even if it is at a mall or a hospital, it adds to the aesthetic appeal of the entire room.

That having said, let’s jump into the common problems faced by people who keep 100 gallon fish tanks.

Disclosure: This article contains affiliate links. When you follow a link to purchase the products, I sometime earn a commission, at no additional cost to you. Read my full disclosure here.

Common Problems With 100 Gallon Tanks and How To Avoid Them

  • Overfeeding
    The number one factor that can result in water getting polluted quickly and fish dying would be overfeeding. If you add more fish food, than necessary, then it can result in algae formation and can require a lot more cleaning than usual. This in turn, can be a hassle owing to the hectic routines.Overfeeding
  • Adding Too Many Fishes In A New Aquarium
    Another problem that arises is when you get too excited about a new aquarium and add too many fishes instantly. Since a new aquarium is like a biological clean slate, the microbes that filter water are not established fully, so a sudden overload of fish waste can create a toxic environment for them. Hence you should add fish only after some time has passed.Adding Too Many Fishes In A New Aquarium
  • Over Cleaning
    When you buy a new aquarium, the biological balance is unstable, hence you should avoid scrubbing the props or vacuuming the aquarium gravel when it does not need it. You may end up eliminating the beneficial bacteria and upset the balance further.Over Cleaning
  • Leaving The Light ‘On’ All The Time
    Since all animals require a resting period, it will be stupid to leave the light on all the time. When in nature, the day and night cycle remains consistent, but in an aquarium, you must ensure that the light has a timer so that your fish do not get stressed out.Leaving The Light ‘On’ All The Time
  • Buying Compatible Fishes
    You must do a plethora of research before buying a new fish and adding it into your aquarium or fish tank. Not all fishes are compatible to live with one another, hence you must find the ones that are compatible with the existing inhabitants and will not outgrow your aquarium. Some fishes even have a water chemistry requirement like low pH that regular tap water may not offer. Hence, you should research these aspects first or else it can be the wrong investment.Buying Compatible Fishes
  • Rust or reddish water
    Well, water’s common iron-rich source water is most likely to blame for the discoloration. This problem may worsen and aggressive algae growth may result from high oxygen levels. The pH adjustments are difficult with hard water.
    Therefore, to stabilize pH, use chemical filter media, such as polyfilters, and water softeners. For a permanent solution, think about a reverse osmosis system.Rust or reddish water
  • Green Water
    Algae blooms can be brought on by too much light or an abundance of nutrients for algae, such as nitrate and phosphate, which are frequently the result of inadequate filtration.
    Use algaecides for short-term relief, but concentrate on regular water changes, the upkeep of activated carbon, and filter maintenance to address the underlying issue. Check the nutrients in the source water, and regulate how long it is lit.Green Water
  • Regular Ammonia Spikes
    Low nitrifying bacteria, which are frequent in new setups or after affecting substrates in mature tanks, are the cause of ammonia spikes. To preserve beneficial bacteria, add bacterial additives frequently and refrain from over-cleaning substrates and filter media.Regular Ammonia Spikes
  • A large number of white or tan worms
    Planarian population growth as a result of excessive feeding or low-quality water is one potential cause. Thus, to improve water quality and control planarians, reduce overfeeding, perform routine water changes, add bacterial additives, and make sure proper filtration is in place.A large number of white or tan worms

Benefits of a 100 Gallon Tank

  • Enhance Species Compatibility: A 100-gallon tank provides ample space to accommodate a wide variety of fish species, ranging from larger Cichlids to smaller sharks.
  • Harmonious Coexistence: The spacious environment minimizes conflicts among fish, creating an ideal habitat for species that do not typically cohabitate well together.
  • Aquascaping: Enthusiasts of marine life and coral reefs can fully explore their creativity by designing captivating underwater landscapes.
  • Mimicking Natural Habitat: The increased size of the tank allows fish to exhibit more natural behaviors and interactions, offering valuable insights into their population dynamics.
  • Visual Delight: Aquarium enthusiasts will be mesmerized by the vibrant array of colorful and diverse fish in a 100-gallon tank, providing a visually stunning experience that boosts mood and enjoyment.

How to Maintain a 100 Gallon Tank?

  • Water Changes: To ensure that your fish are kept in a healthy environment, it is necessary to perform a 25% water change every two weeks.
  • Nitrogen Balance: In order to keep the nitrogen cycle in balance, you must cycle your tank. By doing this, you can make an environment that supports the health of your fish.
  • Water quality: For the well-being of your aquatic inhabitants, it’s crucial to maintain the water quality in your tank at its ideal levels.
  • Dechlorination: Use a dechlorinator to disinfect tap water in freshwater tanks after each water change. The harmful chlorine that could harm your fish is removed in this step.
  • Marine Salts (Marine Tank): It’s important to keep the high salinity levels in marine tanks at the proper levels. Your marine ecosystem will flourish if you add marine salts.
  • Filtration System: For a tank of this size, choosing the appropriate filtration system is essential to preserving the water’s clarity and quality.
  • High-Power External/Canister Filter: By using a high-power external or canister filter, you can maintain the cleanliness and clarity of the water in your tank.
  • Aquarium Pump (Budget-Friendly): To maintain water quality if a high-power filter is out of your price range, think about supplementing your filters with an aquarium pump.
  • pH Levels: Keep an eye on pH levels, which can be affected by algae and decaying plants. If necessary, add distilled water to adjust the pH.
  • Water Hardness: Use a refractometer to measure the hardness of the water, and a litmus paper test kit to check the pH level.

How Many Fish You Can Keep in a 100 Gallon Tank?

Fish stocking in a 100-gallon tank is based on the fish’s size and swimming style. Tetras and other smaller fish can adhere to the 1-inch per gallon recommendation. But larger or oddly shaped fish, like fancy goldfish or angelfish, require more room. For example, a goldfish requires a minimum of a 20-gallon tank, while angel fish benefit from additional vertical space in a 29-gallon tank. Always keep in mind the particular requirements of your fish to provide a safe and cozy environment.


It can be safely concluded that many efforts are needed to maintain a 100 gallon fish tank but would be an excellent accessory for your home and mental health. It’s almost like a stress buster. You must take precautions as mentioned above, and you’ll be good to go. It’s always best to do your own research, instead of making impulsive decisions. Cleaning a fish tank is no joke. It requires hours of manual effort, hence you should be ready for that!

Scott Evans

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