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How To Set Up A Freshwater Aquarium

Updated on June 16, 2013

The Proper Way To Set Up A Freshwater Aquarium

Photo by author taken with Canon Powershot A610

This is like deja vu all over again. I have written a couple of articles on setting up and starting freshwater aquariums, but I'll make one more for the monkey quest. I will also make the instructions a little simpler to understand so that even I can understand what I am trying to say. Believe me, there are days when it is a toss up.

Some Platys, White-Skirt Tetras and Neon Tetras
Some Platys, White-Skirt Tetras and Neon Tetras

Choosing An Aquarium

Photo by author Showing a couple of Platys, White-Skirt Tetras, and Neon Tetras.

Choosing an aquarium is not hard, but there are a lot of different types, styles and sizes to choose from. That can make it more difficult. The first thing to consider is how large of a tank do you want to have. One important consideration for this is the size of your living quarters. If you live in a small "efficiency" apartment, it is doubtful if you will want a 55-gallon tank and a built-in tank is definitely out for any apartment. Remember that deposit on your apartment? You really might not want to go tearing into walls.

But do not fear or fret. There are aquariums that come in small sizes that can keep several small fish healthy and happy. Starting at around 1-gallon sizes that still have filtration systems and can support living plants, on up to 20- and 30-gallon tank sizes and beyond.

If you move from your apartment, you will need to take nearly all the water out of the larger aquariums in order to move them. One reason for this is the weight of the water. Freshwater weighs about 8 and one-third pounds per gallon, so a full 20-gallon tank will weigh over 165 pounds just from the water alone, then there is gravel and other substrate and decorations and plants. All of these things add weight to the aquarium.

Another reason is that the weight of the water in a tank that is being lifted and moved around has been known to cause tanks to develop serious leaks. There are some products that might repair the leak, but usually a leaking aquarium means a new aquarium.

Another consideration for the size of your aquarium is how many fish do you want to keep? Naturally, you can keep more fish in a large aquarium than in a smaller one. By using a bubble stone you not only add an interesting visual effect to your tank, but also help to increase aeration so that you may have a few more fish than if you did not have the bubble maker.

Several Black Mollies

Several Black Mollies
Several Black Mollies

Mollies, especially Black Mollies are one of the most popular breeds for tropical freshwater aquariums. Usually they are a hardy and proliferate breed. They are live bearers, which means that they give birth to living baby fish called "fry." After giving birth, the mother and other fish in the aquarium immediately do their best to eat all the new fry. The fry try to take refuge in plants and other objects in the tank in order to hide from the larger fish until they grow big enough to not be able to fit in the other fish's mouths.


Marineland Eclipse Hex Fully Integrated Aquarium Kit, 5-Gallon
Marineland Eclipse Hex Fully Integrated Aquarium Kit, 5-Gallon

Another of the smaller aquariums for small spaces. This one is built tall so that it leaves a smaller footprint. For more information please use the link.

Koller Products AquaView 3-Gallon 360 with Power Filter and LED Lighting
Koller Products AquaView 3-Gallon 360 with Power Filter and LED Lighting

This is a nice size tank for a small room. It can be set up on an end table or possibly even a bookshelf. The tank is built so that the fish are able to be viewed from any angle without reflection of the other sides like in typical tanks.

Tetra 29137 Water Wonder Aquarium Kit, Black, 1.5 Gallons
Tetra 29137 Water Wonder Aquarium Kit, Black, 1.5 Gallons

This is a small unusual styled tank. It is large enough for a couple of small fish or one betta. The LED lighting system can be adjusted to give some interesting looks. There is room for plenty of decorations too. Please click on the link to see some decorating ideas and for more information about the tank.

Petco Bookshelf Freshwater Fish Aquarium
Petco Bookshelf Freshwater Fish Aquarium

This tank is built long and low so that it can fit on a bookshelf as its name implies. Great for an office, or home study.

Marina Style 20 Deluxe Glass Aquarium Kit - 20 Gallons
Marina Style 20 Deluxe Glass Aquarium Kit - 20 Gallons

This is a larger tank than the others featured here. It really is a deluxe kit that contains everything you will need to set up the aquarium. You just have to supply the fish, plants and water. It also comes in a 10-gallon size with all the same features as the larger model.


Step 2--Preparing to Set Up The Aquarium

A 20-gallon aquarium with fish and plants
A 20-gallon aquarium with fish and plants

After you have picked out your aquarium, you must then set it up for the fish. Please do not buy your fish at the same time you buy your aquarium unless you have a really good place to keep them. They will not live in those plastic bags forever you know. In fact the sooner you can get them out of those bags, the better it will be for them.

Your aquarium will need to sit up for at least a week before you can add any fish to it.

So the first thing you want to do is to make sure that your tank does not leak. With most of the today's smaller sized tanks this is not a problem, especially for those without seams. The more traditional rectangular cube tanks are the ones that need to be checked out. Again this is usually not a problem, but it is better to check it out and make sure before setting up your tank in the place you have picked out for it and then discovering that there is a leak in it.

One of the simplest ways to check for leaks is to put the tank on top of several sheets of dry newspaper and filling it with water. Do this with the tank empty of any gravel, decorations or anything else. Once the tank is filled, let it sit for a couple of hours on the newspaper.

If the newspaper is still dry after a couple of hours, then you can be pretty certain that your aquarium will not leak on you. You can then remove the water (do NOT lift the tank and pour the water out as this can cause the seals to leak) by dipping it out until there is only an inch or two of water left in the tank. Then you can pour out the remainder of the water.

Dry the tank using a clean lint free towel or paper towels.

Place the tank on its stand or wherever it is that you have chosen to display your aquarium.

Be sure to wash your gravel and sand thoroughly before adding it to the tank. Especially if you are adding sand. This will help to prevent very tiny particles of gravel and sand from becoming suspended in the water and making the tank cloudy and the fish hard to see. It will settle eventually, but with filtration pumps and aeration stones working it will take it a much longer time to settle. And then almost anything will set it to rising from the bottom and becoming a cloudy mixture again.

Put in the gravel or gravel/sand mixture and spread it around. A lot of folks like to have the gravel slope from the back of the tank to the front with the back being thicker so that uneaten food and other debris can move toward the front where it is easier to clean up. This is a great idea that even works sometimes. If nothing else, it gives the tank an interesting appearance. You can even add "hills" and "valleys" to your aqua-scaping.

Then place the plants and other decorations where you want them. Remember, you can always move them later if you want to. Also at this time attach the filtration system and heater but do not turn them on until you have the tank filled with water. The filter's pump motor may burn out and the heater may burn out or break the glass the heating element is encase in. So wait until there is some water in the tank before turning these on.

Once this is done, take a regular dinner plate or if that won't fit, a saucer or even small bowl and put it on top of the gravel in the middle of the tank. Your are going to pour the water onto the plate (gently at first) to keep from making a pit right in the middle of the aquarium from the force of the water being poured in and moving the gravel around.

After the tank is from halfway to three-quarters full, you can remove the plate and finish filling the aquarium. Fill the tank until it is about two inches below the rim. Now you can turn on the filtration system and heater. At this time you can add the water conditioner that probably came with your aquarium kit according to the instructions on the bottle.

Check the temperature of the water and adjust the thermostat on the heater so that you have water temperature of between 72 and 82 degrees Fahrenheit (22 - 28 degrees Celsius). It takes a while to get 20-gallons of water heated to the right temperature, so be prepared to take your time and check the temperature often. Make only very small adjustments until you have reached the desired temperature. Let the filtration system run during the "break in" period. Allow at least one week for a break in period before adding fish to your tank.

You will want to put in fish that are hardy and can take the stress of the tank going through its normal nitrogen cycle. Guppies are generally good for this and your pet store people can also make recommendations. It takes a while for the "good" bacteria to build up and get rid of the very toxic ammonia and only slightly less toxic nitrites in the tank. A good water testing kit is recommended, or you can take a sample of the water to your pet store for testing. Most of them will do this for free.

Fish Need To Eat

Tetra Tropical Color Flakes, Clear Water Advanced Formula
Tetra Tropical Color Flakes, Clear Water Advanced Formula

The Tetra brand is a recognized brand by fish hobbyists. The company has developed several types of dry flake fish food that serves different purposes for your fish. This type of food is to enhance the colors of your fish. For most aquarium a one liter size is a LIT of fish food.

TetraMin Plus Tropical Flakes, Cleaner and Clearer Water Formula
TetraMin Plus Tropical Flakes, Cleaner and Clearer Water Formula

This TetraMin Plus is a general purpose fish food that will keep most tropical fish healthy and give them the nutrition they need.

Tetra Blood Worms Freeze Dried Treat, 0.28-Ounce, 100-Ml
Tetra Blood Worms Freeze Dried Treat, 0.28-Ounce, 100-Ml

Let me ask you a question. Do you think you would like to have the same thing for every meal without any variety al all? Of course you wouldn't. Most fish eat living things in the wild. These bloodworms are freeze dried so they are not living, but they will add variety to your fish's diet and provide needed proteins.

TetraMin Tropical Crisps, Clear Water Advanced Formula
TetraMin Tropical Crisps, Clear Water Advanced Formula

This is what the product description reads like:

The Ultimate in Fish Nutrition

Healthy, easily digestible protein, vitamins, and carbohydrates that bring out the best appearance in your fish

Reduces fish waste and improves water clarity

Sounds yummy if you're a fish.


The Nitrogen Cycle

A Tank That Has Gone Through The Nitrogen Cycle
A Tank That Has Gone Through The Nitrogen Cycle

Before this nitrogen cycle was fully understood, hobbyists lost plenty of fish due to the presence of these nitrogenous compounds in their new tanks. I am not going to go into the chemistry of the processes involved because they are quite complicated and somewhat difficult to explain to someone that does not have a background in chemistry. I myself have a good background, but since it had been years since I had used any of this knowledge, I had to do some research on it to be sure that I had it right in my mind.

Basically here is what occurs in a new tank. Due to the presence of uneaten fish food becoming spoiled and breaking down through natural process a nitrogen compound called ammonia is formed in the tank. Living fish also produce ammonia in their natural body processes and it is excreted in their urine and feces and a small amount from respiration in the gills. Ammonia is highly toxic to fish and other living organisms including some plants.

In nature, this ammonia usually does not prove to be a problem because it is generally swept away by currents in the water and diluted out to levels that are harmless. But in an aquarium, the ammonia has no where to go so it remains in the tank and presents a hazard to your fish.

Certain bacteria and some plants use the ammonia and convert it to another form of nitrogen compound called nitrites. Although the nitrites are toxic to the fish, they are less toxic than the ammonia. It takes a little while, but other bacteria then form in the tank and act to convert the nitrites to much less toxic nitrogen compounds known as nitrates.

Although the nitrates are less harmful than the nitrites and far less harmful than ammonia, a build up of nitrates in the aquarium can cause stress to the fish and may eventually increase to toxic levels if not removed. The best way to remove these nitrates is by a change of water in the aquarium. Usually a change of about one-third of the water will prove to be helpful. This fresh water is usually tap water, and it must be conditioned to remove chlorine and certain heavy metals such as copper and iron.

Some hobbyists will set up and treat their fresh (tap) water the day before to prepare it for going into the aquarium. Some of them even put in a spare heater so that the temperature of the fresh water is the same as that of the aquarium and the fish are not subject to a sudden temperature change.

The water that is removed from the tank is then disposed of. Some use it to water their house plants since it contains nitrates which are found in fertilizers. Some of the water can be used to add to a new aquarium that is being broken in. In that case, no more than one-half of the water is "old" water from another aquarium while the remainder is fresh tap water that has been conditioned to remove chlorine and other unwanted chemicals. Too much of the "old" water will put you right back in the position of having too many nitrates in the water.

It seems that the largest build up of these beneficial bacterial is in the filter of the aquarium's filtration system. This would mean that it would not be wise to change the aquarium water and the filter at the same time. The filter should only be changed a couple of weeks after the water change has taken place or even change it out before changing the water. That is so that the "good" bacteria will have time to build up a good population in the aquarium from those that were in the filter.

A used filter like we have been discussing may even be used in another aquarium that has not yet gone through its nitrogen cycle. Just place that "used" filter in place of the filter in the filter pump system and let it spread its bacteria into the new tank.

One important point is that it takes the presence of fish in the aquarium in order for this process to cycle through. (This is not exactly true since the use of fish food in the uninhabited tank will also work and no fish are killed by doing this.) Because of this some fish may be lost while the tank is cycling through. It is wise to use some types of fish that are somewhat tolerant to the presence of the nitrogen compounds so as to cut down on the number of fish that are lost. It breaks my heart whenever one of my fish die for whatever reason, and I know that people who keep fish feel the same way.

One kind of fish that is recommended for this is guppies. But some people don't want to raise guppies. I suggest that you talk to your local fish supplier to find the fish best suited for your needs. In saying this, I am talking about a person who runs a tropical fish store as opposed to someone who works at say Wal-Mart.

I have nothing against Wal-Mart, but I have noticed that the aquariums in every Wal-Mart I have ever been in have not been well cared for. Often there are dead fish floating at the top of the tank, and the personnel that work them usually are there for only a short term and so they will usually not know much about taking care of the fish. They only catch and sell them.

So I have told you this to prepare you for the fact that some of your fish may die while your new aquarium is going through this nitrogen cycle. There are some products that claim to be able to shorten or even eliminate the processes by adding the correct kinds of bacteria to your tank when you use their product. I have not heard one person in a fish store give their blessings to these products. They usually say that it doesn't hurt to use them and maybe they might do some good, but it generally just takes time for Mother Nature to fix up the aquarium for healthy fish. Sometimes over three weeks is needed for the tank to fully cycle through.

Supplies You My Need For Your Aquarium

API FRESHWATER MASTER TEST KIT 800-Test Freshwater Aquarium Water Master Test Kit
API FRESHWATER MASTER TEST KIT 800-Test Freshwater Aquarium Water Master Test Kit

This is a must for testing your aquarium's water to make sure that everything is going the way it is supposed to go. I use this type testing kit for my aquariums and it has helped me get through the nitrogen cycle that can kill fish.

Aqueon Aquarium Water Changer - 25 Feet
Aqueon Aquarium Water Changer - 25 Feet

Hook this up to a standard kitchen faucet and it will use the vacuum created by the tap water to remove water from your tank and send it right down the sink's drain. When you have removed enough water, just turn the valve and it will then begin refilling your tank. There is even a kit available in case your aquarium is more than 25 feet from your sink.

Koller Products TOM Aquarium Algae Scraper Multi-Tool, 22" Length
Koller Products TOM Aquarium Algae Scraper Multi-Tool, 22" Length

Use it like a squeegee to clean the inside of your aquarium walls of algae and any other unwanted things that may be on them.

Penn Plax Airline Tubing for Aquariums –Clear and Flexible Resists Kinking, 25 Feet Standard
Penn Plax Airline Tubing for Aquariums –Clear and Flexible Resists Kinking, 25 Feet Standard

You will need tubing to attach an air pump to a bubble stone and to other aquarium decorations that run off of air power.

Penn Plax PPX Aqua Mist Add A Stone 10+ACI-
Penn Plax PPX Aqua Mist Add A Stone 10+ACI-

Place this in the rear of your aquarium and it will send a curtain of small air bubbles up for a dramatic effect.


Do you now or do you plan to keep tropical fish?

A Fancy Show Guppie
A Fancy Show Guppie

Do you keep tropical fish?

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Keeping fish may cause you to watch a whole lot less television than you are used to watching.

Please Leave A Comment Or Just Say Hi! - I like to know who's been here so I know who to thank.

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    • profile image


      2 years ago

      Thank you so much for the great info. I'm just about to start setting up a new aquarium and I needed some advice.

    • DuaneJ profile image


      5 years ago

      I'm a big aquarium enthusiast. I currently have two freshwater aquariums. The small one houses tiger barbs, rosy barbs and danios. The bigger one houses two my big beloved oscars. I've had them for 5 years now :-)


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