How to Clean a Fish Tank

6 min read

Image via Alexander Geiger/


By Kali Wyrosdic


Setting up an aquarium can seem intimidating at first, but once you get your feet wet you’ll see that aquariums are much easier to setup and maintain than you thought. All it takes is getting into a good routine plus a little elbow grease and you can have a freshwater aquarium setup (or cleaned) quickly and easily. Get the complete details on how to set up and clean a fish tank, plus answers to some common questions about fish-tank maintenance, below.


How to Set Up a Fish Tank


Once you’ve got your equipment and designated a good spot in the home (out of direct sunlight and free of drafts) to keep the aquarium, follow these ten easy steps to set up and clean your freshwater aquarium:


Step one: rinse the tank with warm water, wiping it out with a paper towel if necessary. Do not use soaps or detergents of any kind; they’ll kill your fish.


Step two: thoroughly rinse off any gravel, aquarium rocks and any other tank decorations with warm water before placing them into the empty tank. Use a colander to rinse the gravel and rocks until the water runs through clear and free of debris.


Step three: fill your tank one-third of the way with room temperature aquarium-specific water from a clean bucket. There are two types of aquarium-specific water you can use: pre-treated, fish-safe aquarium water by the bottle from your local pet store or tap water that’s been treated with a conditioner like Tetra AquaSafe or EasyBalancePlus to de-chlorinate and remove other harmful chemicals and heavy metals. If you choose treated tap water, always follow the directions on the back of the bottle.


Step four: connect your airline tubing from the pump to any bubble bars or decorations you have.


Step five: aqua scape with any fake or live plants you want to include. Ideally, these can be arranged to hide your air pump and filtration equipment. If you choose live plants, make sure the water is warm enough before planting them in the gravel or you’ll shock the roots and kill the plant.


Step six: finish filling the tank with water, leaving some space between the water and the cover of your tank (especially if you have fish that are prone to jumping).


Step seven: setup your filter and cycle your tank. “Cycling” a tank refers to the growing of healthy bacteria on a new filtration system, which removes dangerous toxins and preps the tank for your fish. You’ll want to set up your filter whether it’s an outside or hanging filter by priming it (filling it with water).  You can use over the counter aquarium-specific liquid ammonia or starter fish to accomplish the task of cycling. The length of cycling time is dependent on many factors, so research it carefully for your specific tank.


Step eight: affix your submersible heater next to the water flow in your aquarium then place an in-tank thermometer on the opposite side of the tank as far away from the heater as you can.


Step nine: plug in and turn on the air pump, power filter and heater. Let your setup run for 24 hours before adding any fish (this provides time for the temperature to stabilize and you to make any necessary adjustments) and check the conditions and temperature every few hours. Don’t worry if the tank gets cloudy for a day or two; this is natural and caused by a harmless bacterial growth that usually goes away on its own.


Step ten: after waiting 24 hours, introduce your fish to their new home by floating the bag your fish comes in in your tank water for about half an hour to equalize the two water temperatures. Once your fish has been floating in the bag for about 15 minutes, add some aquarium water to the bag. After 15 more minutes, take a fish net and gently remove the fish from the bag and place it in the aquarium.


How to Clean a Freshwater Aquarium


Cleaning your aquarium isn’t as hard as setting it up. Monitor the pH levels and visible gunk regularly and change your filter cartridge every two to four weeks. Perform a 25 percent water change every two to four weeks as well. You can use algae scrubbers and other tools to keep your aquarium looking spiffy between cleanings and changes.


To change the water, turn off the heaters, pumps and filters and remove all the decorations and plants from the tank. Wash everything in warm, clean water and set them aside. Try not to remove your fish too often when cleaning, as it’ll cause them stress and can make them sick. If you must, gently remove your fish with a net and place them in a large glass or bucket with some of the original tank water.


Using a gravel cleaner or homemade siphon and vacuum the gravel until you’ve removed about one third of the water from the tank. This should give you ample time to clean almost all of the gravel (and anything you don’t get to you’ll be able to clean next time). Always make sure to replace the old water with fresh, pretreated water that’s the same temperature as the old water.


It’s a good idea to keep all your aquarium supplies together. Setting aside your sponges, towels, buckets, nets and scrubbers will help prevent the introduction of any harmful pollutants into your aquarium.


Commonly Asked Fish Tank Questions


Q: How do I get rid of algae in my fish tank?

A: Algae is bothersome and grows in every aquarium, but you don’t have to wait for your regular aquarium cleanings to get rid of it. Tools such as simple scrubbers or magnetic scrubbers can be used to gently scrub the algae off your tank walls.


Q: How do I clean fish tank gravel?

A: Buy a gravel cleaner from your local pet store, or make your own siphon out of a length of plastic tubing and use a water bucket.


Q: How do I clean a fish bowl?

A: Fish bowls are a lot like aquariums, but they need to be cleaned much more frequently, especially if they aren’t equipped with a filter. If the fish bowl doesn’t have a water filter, change the water frequently, but only by 10-to-15 percent of it at a time. For small fishbowls, remove the fish and place them in a large glass with enough water from the tank to make them comfortable. Then, follow the above instructions for scrubbing the sides and decorations, making sure to never use soap or detergents.


Q: How many fish can live in a 10-gallon tank?

A: It depends on many factors, including the breed and size of fish you plan on buying. For small, slim-bodied fish like neon tetras, cloud minnows, danios and gourami, a good rule of thumb is one inch of fish per gallon of water. However, you’ll need to consider your filtration system, if there are any healthy live plants and how often you change the water as these could change the number of fish you can have in the tank.  


Q: Can I use table salt to make my freshwater aquarium saltwater?

A: No. Adding marine salt to freshwater aquariums has been used for stress reduction or for fish tanks that house fish native to brackish water, but you should never add table salt to a freshwater tank in an attempt to make it a saltwater tank. Most wild freshwater fish and plants come from areas with little-to-no detectable sodium. Freshwater fish are adapted to water that has salt content measured in parts per million (ppm) whereas salt in seawater is measured in parts per thousand (ppt). Most freshwater fish cannot adapt to saltwater conditions and will quickly become dehydrated if placed in a saltwater tank.