How to Setup Your New Freshwater Aquarium – A Guide to Setting Up Your Fish Tank

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Setting up a new aquarium is easy, but it can take some time before you can safely add plants, fish, and other creatures.

If you plan well, and allow plenty of time for each step in the process, you can look forward to many years of enjoying a beautiful aquarium filled with healthy inhabitants.

As you go through this detailed guide, it will help to have some ideas about the water chemistry and environmental needs of each species you plan to house in the tank. 

Equipment YOu’ll Need

It can take just a few weeks to several months before it is safe to add fish to your new tank.

Here are the tools and equipment you will need for each stage of the process. Make sure you don’t rush it, as some materials release trace elements that need time to naturally clear before adding fish to the tank.

freshwater aquarium setup man feeding finished aquarium

Initial Equipment Checklist

  1. Level – very important for making sure that the stand is perfectly level. 
  2. Step Stool – a step stool makes it much easier to reach the bottom of the tank without leaning into the walls of the tank or putting excess pressure on the upper lip of the tank as you reach into it.
  3. Tank Stand
  4. Aquarium and Hood
  5. Waterproof Floor Covering – At least 1 – 2 feet all the way around the stand. No matter how hard you try, water can and will spill during water changes and other maintenance operations. Waterproof floor covering can help save your floors from water damage.
  6. Corrugated Cardboard – Choose 2 pieces that are at least 1” bigger all the way around the bottom of the tank. The corrugated cardboard will provide cushioning for the bottom of the tank, which can help extend the lifetime of the seals. 
  7. Aquarium Safe Sealant – Keep this mainly for emergency purposes after the tank is out of warranty.
  8. Primary Aquarium Filter – there are many kinds of filters to choose from. Use a high power filter or canister filter for larger tanks. Smaller tanks will still have good water flow and filtration even with bubble up filters. 
  9. Airstones or Air Curtain (Depending on Tank size) – Even though you will not be putting fish in the tank right away, aerating the water keeps it fresh and free of harmful pathogens. 
  10. Water – the first few days will be mostly dedicated to checking for leaks. Unless you have polluted, cloudy tap water, or it’s water chemistry is very different from what you need, you can go ahead and use it at this stage. 
  11. Power Supply Strip – Many aquarium devices either do not have power switches or have them in places where you will have to reach behind the tank to get to them. A power supply strip with dedicated power buttons for each socket will make aquarium maintenance easier and safer. 
  12. Battery Power Backup – If you lose power and heat, you may lose all the creatures in the tank. The battery system should be able to accommodate enough heaters plus the air and filters for 24 hours and be rechargeable by some means other than the main power outlet. 

Equipment for Days 3 – 5

  1. Water Conditioner – Choose a brand that will neutralize, at a minimum, chlorine, chloramine, and ammonia. It will also help to look for one that will chelate heavy metals. I have used Jungle’s Start Right for decades, and find it works best.
  2. Water Chemistry Additives – you should always have pH adjusters (up, down, and crushed coral), water softening pillows, and aquarium water hardening agents. Some tanks may also require aquarium salt or other chemicals to create and maintain optimal water chemistry in the tank.
  3. Bubble Up Filters and Media – even though the main filter should supply enough water circulation, you may still need some additional aeration combined with other media to solve emergency water quality problems. I always keep zeolites (they lock up ammonia), activated carbon, and filter floss onhand. It is also important to have a good air pump, check valve, and air control valves to use with the bubble up filters.
  4. Fertilizers or other Plant Care Needs – Depending on the plant species, you may need CO2 injectors, trace elements, and other fertilizers. 
  5. Plants – Live plants play a key role in developing and maintaining healthy water chemistry. While some people say you can let a tank complete its first nitrogen cycle without plants, I have always found it best to add them at least one month before adding the fish. 
  6. Decorations – Driftwood, some gravels, stones, and other materials may have chemicals in them that leach into the water. Placing the decorations in the tank early on gives you a chance to monitor water chemistry and how the decorations impact it. 
  7. Testing Strips and Meters – Most aquarium keepers use a test kit with disposable testing strips to monitor pH, hardness, ammonia levels, nitrates, and nitrites. You may also be interested in electronic meters. A good quality meter may also measure salinity, and other water chemistry elements that you cannot measure with strips. If you are going to use CO2 systems for plants, I definitely recommend a meter for measuring oxygen content in the tank.

Post-Initial Cycle

Once you’ve cycled the tank for the first time, it’s now safe to add your fish, so you’ll want to make sure you have the following items.

  1. Aquarium Fish and Other Animals
  2. Water Siphon
  3. Algae Scraper
  4. Fish Net
  5. Fish Food

Basic Steps For All Freshwater Aquariums

Regardless of the size or shape of the tank, there are some basic steps that apply to all aquariums.

That being said, if you are starting a tannin-rich tank, or one for livebearers, there are some things you may need to adjust in order to create the best possible water chemistry and environment. 

1. Planning

One of the worst things you can do is go to a local pet store, see some cute tropical fish in a tank, and decide to buy a few on the spur of the moment. Proper planning is essential if you want to give your new pets the best possible home.

Here are some questions you should consider before you even buy a fish tank and suitable inhabitants.

  • What type of fish are you most interested in keeping? Since freshwater tropical and cold water fish come in many shapes, sizes, and colors, it is best to take your time making a list of possible inhabitants for your tank. At this stage, it is absolutely fine to have 50 or more different species on your list. 
  • What is the tank size and basic care level required for each species you are considering? 
  • What are the water chemistry needs for each remaining species on your list? It doesn’t matter if you choose to keep just the alkaline, acidic, or neutral water thriving fish on your list. The important thing is to narrow it down to one pH. Next, you will need to look at the remaining fish and choose between hard and soft water fish. 
  • Will the remaining fish on your list make suitable tank mates? At this stage, you may only have 2 or 3 species left on your list of prospective aquarium inhabitants. As long as they are compatible in temperament, and there is enough room in the tank, you may be able to have multi-species in the tank.

Repeat the above questions for plants and other inhabitants such as snails, shrimp, and other creatures. Once you have these lists in place, go back and compare them to the fish and other inhabitants for compatibility. 

2. Choosing a Location

Now that you have some firm ideas about the plants and animals that will live in the tank, it is time to choose a location. Here are some things to look for:

  • The area should be free of drafts and odors – Pay careful attention to where and how cooking odors, smoke, and other airborne chemicals tend to make their way around. Try to avoid areas where odors collect or build up. Things that may not pose a threat to you can be toxic to aquarium inhabitants.
  • Make sure the floor is level and sound – One gallon of water weighs about 8 pounds. A ten gallon tank plus gravel and water will weigh over 100 pounds, not counting the stand. If your footsteps cause floorboards to squeak, or the floor feels shaky, it will not be a good place for an aquarium. It is also very important to make sure the floor is level. While you may be able to brace the aquarium stand to compensate for an uneven floor, I don’t recommend that unless you know the building’s foundation is solid. 
  • Choose a Room Where the Temperature Will be the Same as the Optimal Range for the Tank – This will mostly eliminate the need for adding heaters to the tank. 
  • Avoid windows and other strong lighting sources – Many fish get started and will bash into things when lightning strikes nearby or car lights startle them at night. Direct sunlight and excess light from windows or other sources will also contribute to algae problems. Finally, depending on the angle of the light, it can also create mirror effects inside the tank that will cause fish to act erratically.
  • Avoid areas where sharp vibrations can shake the tank – Vibrations that rattle your dishes and glassware can also disrupt aquarium water in a way that is very stressful to the fish.
  • Avoid areas with loud or sharp sounds – Some fish are very sensitive to loud sounds and will become disoriented if there is too much noise.
  • Avoid areas where pets and young children can get near the tank unsupervised.
anubias-and-other-plants-in-a-fish-tank

3. Setting up the Tank

Once you choose a suitable location, actually setting up the tank is fairly easy. Just follow the manufacturer’s instructions for setting up the stand. Make sure it is level on all corners and sides before installing the aquarium. 

As something of an aside, many aquarium stands do not have a solid surface beneath the tank. Instinctively, these stands make me very nervous because of the amount of weight from the water pushing down on the glass or acrylic. To be on the safe side, I always recommend using ¾ plywood to cover the bottom of the stand, and then the two layers of cardboard on top of that.

Many fish keepers are sure to disagree with me on this; however, I have yet to have a tank spring a leak let alone completely fail in over 25 years. 

4. Check the Tank for Leaks and Environmental Suitability 

When filling the tank with water, pay careful attention to the maximum water line location.

Going over that limit can lead to tank seal and wall damage. Regardless of the material the tank is made from, wait a few days after filling with water to make sure there are no leaks. 

During these first few days, you can install and run the primary filter (without zeolites) so that the water does not become stagnant, and test the backup power system.

This is also a good time to see how other environmental factors such as sounds, odors, and lighting affect the aquarium. If you notice problems, this will be the easiest time to simply remove the water from the tank and set it up in another location.

5. Add Substrate 

The best substrate for your aquarium will depend on its size, and the kinds of creatures you plan to keep in the tank. You will need approximately 1 ½ pounds of substrate for each gallon of water. There are three main kinds of substrate you can choose from:

Gravel

This is the most common substrate and works well for aquariums with plants and most kinds of fish. Gravel is the best choice for colonizing nitrifying bacteria, and is also the easiest to clean with a siphon. 

Aquarium gravel also comes in many colors, which makes it easy to use with numerous themes and color arrangements. I personally prefer undyed gravel because there is less chance of winding up with paint or dyes that may chip off or leach into the water. 

Check our reviews of the best gravels here.

Sand

Sand is ideal for tanks with shrimp, and fish that like to dig in it for one reason or another. I tend to avoid using sand because it compacts too much and makes it harder for beneficial bacteria to colonize the substrate. 

Some authors claim sand is easier to keep clean because food and other materials cannot get below the surface. Quite frankly, I never had such a mess in my tank as when I used sand because I had to put a filter on the siphon outlet to prevent the sand from leaving with the debris. That, in turn, caused the filter to clog up! 

If you want to try using sand in the tank, I recommend using plastic dividers so that you can have some sandy areas and some with gravel. Use a fish net covered with a coffee filter to gently stir up the sand and then try to catch debris in that when it needs cleaning.

Be ready in increase cycling of the main filter (if it has that capacity), or use a bubble up filter to pull the debris out of the water as quickly as possible after scraping the bottom.

Check our reviews of the best sands here.

Aquarium Soil

As with sand, I would only put aquarium soil in areas that are partitioned off with plexiglass dividers.

It is useful for plants that require more nutrients from root based feeding.

Never use pond soil, potting soil, or other land-based soils in an aquarium. Some may have dangerous chemicals and fertilizers in them while others will simply cloud the water and make it impossible to keep clean.

Regardless of the substrate type, you can use the same basic process for placing it in the tank.

First, wash off the substrate in clean water. Use a plastic strainer (never use metal tools unless they are certified safe for freshwater tanks!) to rinse out the substrate until the water runs completely clear. 

If you are going to use plexiglass to build substrate terraces or partitioned areas, go ahead and install those forms. As a word of caution, I also don’t recommend putting heavier loads of substrate in one area, and lighter in others. You can always put plexiglass bottoms in taller partitions so that the weight distribution of the substrate is the same in all areas of the tank. 

Next, put the substrate in a gallon-sized, food-grade plastic bag. Lower the bag to the bottom of the tank, and gently release the substrate from the bag. Use your hands to spread the material out and repeat the process until the substrate is thick enough.

Never simply dump sand, gravel, or any other substrate into the tank from even a small height. It is all too easy to scratch or chip the bottom of the tank without realizing it. 

anubias-and-other-plants-in-a-fish-tank

6. Install Equipment

There are many different kinds of equipment that you may be interested in using in your freshwater aquarium. Aside from the primary filter, now is the time to install the following:

Thermometers and other gages

Since you will starting the process of adjusting the water chemistry very soon, now is the time to install pH and other electronic monitoring systems if you choose to use them. 

Additional air support

Install airstones, air curtains, and regulation valves. Do not forget to add a check valve right after each device and before any splits in the tubing. Some people only put one check valve on the primary line from the pump to the devices. I prefer to ensure there are no possible places where water backup into the line can cause a leak that empties the tank.

Over time, aquarium tubing can and will stretch around valve and connector ports. In some cases, that will create a better seal. In other cases, it can increase the risk of a leak. 

Heaters

If you cannot keep the tank in a room where the temperature will remain in the optimal range, you will need to install heaters. Follow manufacturer instructions for setting the temperature and then watch carefully for a few days to make sure you have a good sense of how the heaters work. 

7. Add Decorations

Before adding decorations, scrub them in water to make sure they are free of dust and anything that might flake off. In the case of driftwood, it also helps boil and rinse (repeatedly until the water remains clear) before adding it to tanks that won’t be tannin rich. 

Always start off by introducing decorations upside down until they are completely submerged in water. Shake the decoration a few times, and then turn it right side up while submerged. This process ensures the decoration doesn’t have trapped air pockets that may be harmful to fish and other creatures. 

8. Add Some Plants and Fertilizer

In order to establish the nitrogen cycle in the aquarium, you will use plants to break in the water. Choose plants that will survive a wide range of pH fluctuations as well as any changes you might make to lighting, water hardness, and salinity along the way. 

Some people will tell you soak plants in a mild bleach solution, or try to quarantine them before adding them to the tank. I have never found either method to be of use simply because all fish carry opportunistic infections. 

When adding your first batch of plants, be sure to leave enough room for new plants that you might want to add once the water chemistry stabilizes. It will also help to add some fertilizer since it will be at least one month before there is enough fish waste to provide adequate nutrition for the plants. 

Once the tank is fully cycled, you can go ahead and add plants of interest that have more stringent water chemistry needs. This process can take several months to one year depending on the number of fish in the tank and the amount of waste they produce.

9. Preparing the Water

Once the first batch of plants are in place, it is time to test the water for pH, hardness, nitrites, ammonia, and nitrates. If the pH and hardness are outside the optimal parameters for future inhabitants of the tank, go ahead and make adjustments. Do not take steps adjust ammonia, nitrites, and nitrates.

freshwater aquarium with plenty of fish

10. Cycle the Tank

As mysterious as this process sounds, it is actually nothing more than letting the filters run in the tank until ammonia and nitrite levels drop to zero. Depending on the amount of water in the tank, this can take as little as 3 weeks, or it can take several months. 

During the cycling period, test the water every 5 days for pH, hardness, ammonia, nitrates, and nitrites. You can adjust pH and hardness as needed, but do not try to adjust the ammonia, nitrites, and nitrates. At this stage, these three waste products are needed by the nitrifying the bacteria. Getting rid of them will just starve and slow down the very process you are trying to establish. 

It should be noted this is the only time you should not be concerned about seeing ammonia and nitrates in the tank. After you add fish and other creatures, the toxic potential of these chemicals means that you have to neutralize them as quickly as possible. 

You should see a sharp rise in nitrates and nitrites followed by a gradual decline. Once ammonia and nitrites reach zero, it is safe to start putting fish and other creatures in the tank.

Special Aquarium Setup and Water Chemistry Considerations

Even though the setup process is essentially the same, there are some special points to keep in mind if you are setting up a tank with a specific water chemistry, as well as how size impacts water chemistry.

Small Tank (1 to 5 Gallon Aquarium)

Small tanks have a lot less water volume, so conditions can change to extremes rapidly until the tank reaches a balance. Once the tank is cycled, I recommend keeping at least 50% zeolites/50% activated carbon in a separate bubble up filter, plus nitrate absorbing pads. 

Since small tanks have very little room to begin with, I don’t recommend using plants in them that require CO2 injection. Oxygen in small tanks can get used up very quickly, especially if the fish are stressed or overstocked. In small tanks, the situation can go from fine to deadly in less than an hour.

Medium Sized Tanks (6 – 20 Gallons)

For the most part, tanks in the 10 – 15 gallon range are the best in terms of being able to adjust water chemistry easily as well as stabilize it to new levels. Unless you need highly alkaline water, these tanks usually don’t require extra buffering to maintain a higher pH. 

Insofar as plants, I also don’t recommend ones that require CO2 injection for these tank sizes. Even though there is more water volume, it still isn’t enough to prevent a deadly emergency if the plants themselves start emitting CO2. As strange as it may sound, some plants will actually stop emitting oxygen when too much CO2 is present. 

Large Sized Tank (21+ Gallons)

Once you start getting into tanks larger than 20 gallons, it becomes much harder to change the water chemistry, and then stabilize it at a new level. Where it may only take a day or two to adjust the pH in a smaller tank, you may struggle with it for a week or more in larger tanks. 

Even if you use natural or chemical pH buffers, you will need to test the pH daily for at least 5 – 10 days after nitrates and ammonia reach zero, and continue to monitor on a daily basis.

I’ve had some tanks stabilize and then stayed balanced in about two weeks, while others took several months.

Neutral and alkaline tanks tend to be harder to stabilize because most processes going on in the tank tend to push it towards acidic. 

Larger tanks are the best suited for plants that require CO2 injection. It is still important to monitor oxygen levels in the tank, and keep oxygen tablets onhand to address emergency lows.

 Brackish Water Tanks

Even though brackish water fish can tolerate a wide range of salt levels, it may help to match the optimal for the current weather season.

As time goes on, you can adjust the salinity from the starting point to mimic changes that would occur as they migrate, or during times when the levels change because of rainfall. 

 Tannin Tanks

You can use natural driftwood known for producing tannins and simply add it to the tank. Within a few weeks, the tannins will leach out and produce the famous clear brownish colored water that these tanks are known for. Since tannin-rich tanks are also very acidic in pH, it is important to monitor the pH carefully. 

Along with pH Up (to make the tank less acidic), I also use crushed coral in a bubble up filter because it will dissolve more slowly as the pH rises. This is very useful for preventing rapid swings downward. Since driftwood can be unpredictable, simply using pH up will not always work. 

cichlid freshwater fish

How to Add New Fish and Other Creatures to Your Cycled Tank

Start off by adding a temporary bubble up filter with 50% zeolites and 50% activated carbon as a precaution against ammonia surges that can occur when fish are stressed, and when adding a sudden load on the biofilter.

There are several factors that influence the method you use to transfer fish or other creatures from the transport bag to the home tank. In order to choose the best method, you will need to know the answer to the following questions:

1. Did the fish come directly from a breeder or are they from a retail seller?

Usually, if you buy fish directly from a breeder, they will be raised and kept in optimal water conditions. As a result, matching the water they come in will be important. Even though you may need to adjust water conditions later on to spur breeding, it is best to start the fish off with water chemistry that is closest to their current living conditions.

Fish from retail sellers, on the other hand, may have spent only a few hours to a few days in the retail tank. Depending on the seller, the water also may or may not be optimal for the species in question.

Under these circumstances, the faster you get the fish back into water with optimal parameters, the better.

All you need to do is float the bag in the tank for about 15 minutes to equalize the temperature, and then release the fish into the tank.

2. Are the fish injured or showing signs of illness?

Even though your tank may be brand new, it doesn’t make sense to put fish with damaged fins or disease symptoms into the new tank. Put these fish in a hospital tank instead so that they have a chance to recuperate.

You will still need to put antibiotics in the home tank just in case other fish from the same group are on the verge of getting sick.

3. Do the fish have specific acclimation needs?

While there are many species of fish and other creatures that can withstand a good bit of water chemistry change, others cannot.

For example, many species of miniature shrimp require a special adaption process that can take several hours or days.

Since there are many species of fish and other creatures to choose from, it is best to consult care guides for each species to find out if you need to do more than pay attention to water temperature.

Troubleshooting

 Here are some common problems you may come across while setting up your new tank:

Tank Leaks

If the tank is brand new, it should not have leaks. The best thing you can do is empty it out and return it immediately to the store where you bought it from.

If the tank is over 30 days old, you may have to work with the manufacturer to get a refund during the remainder of the warranty period.

Even though it is possible to repair aquariums, I don’t recommend it for brand new tanks because it may be just the beginning of more leakage problems. 

Cloudy Water

Rinsing everything carefully before you put it in the tank usually prevents cloudiness from gravel, filter media, and other types of dust. If you do get some debris, the filters should remove it within 24 hours. 

Add one bubble up filter with just floss in it for each 5 gallons of water to remove the debris if the main filters aren’t clearing the water. There are also chemical chelating agents that will pull debris down to the substrate level. I don’t recommend them because I’ve never seen them work properly.

Three or four days into the tank cycle, tiny micro organisms, or infusorans, may multiply rapidly and cloud the water. This is actually a good sign because it means there will be plenty of food for nitrifying bacteria once the infusorans die off. Once the cloud clears, the tank is well on its way to having a robust and healthy nitrogen cycle.

Foul Odor

Infusora die-offs should not cause a foul odor in the tank. Pay careful attention to ammonia levels in the tank, and also make sure insects or other unwanted creatures haven’t found their way into the water.

Usually, even an established aquarium will not suddenly develop a foul odor unless something is dead in the tank. This includes large numbers of plant leaves as well a fish or other animals. 

As long as the water chemistry is good, plants are properly trimmed, and the tank is not over stocked, you should not have any kind of foul odor in the water, simply because waste products will not build up to cause problems. 

Decorations, Filters, and More Don’t Stay in Place

There is no getting around the fact that plants, thermometers, bubble up filters, and many other items will float in the water if not anchored properly. Over the years, I have found that different objects require different anchoring methods. 

First, try to avoid plants or toys made from plastic or other lightweight materials. Aside from the potential for injuring fish, they do nothing useful for the water chemistry. Dense wood, ceramic, and stone toys usually won’t develop buoyancy problems. 

The easiest way to deal with bubble up filters is to attach a suction cup to the airline tubing, about 2 inches up from the top of the filter. Simply affix the suction cup to a side of the tank so that the filter bottom rests on the substrate surface. 

Use aquarium safe thread or fishing line to tie moss and other plants to driftwood or other less buoyant items in the tank. Even if the plants will eventually have large root systems, this will also help in tanks where you plan to have fish that will disrupt the substrate or dig around the roots. 

Final Word

As you can see, starting a new aquarium isn’t especially difficult, nor does it require a lot in terms of complex devices and tools.

Taking the time now to let the tank cycle properly will make it much easier to care for all the inhabitants of the tank. It will also give you more time to learn more about the fascinating world that aquatic creatures inhabit.

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