Aquarium Questions and Answers

Got Questions? Need Aquarium Help? We have answers.

Red FishWant help from the experts? Just “Ask Tetra!” Here you can browse through questions that other fish enthusiasts have asked, or ask your own questions about products or problems you may be experiencing.

If you don’t find the answer to your question here, you can e-mail us at TetraCare or call 1-800-423-6458.
(Choose a category for a complete list of questions)

Aquarium Cleaning and Setup
Aquarium Product Setup
Aquarium Equipment Problems
Aquarium Fish Setup
Aquarium Water Problems
Aquarium Product Maintenance
Aquarium Fish Maintenance



Aquarium Cleaning and Setup

Q. How do I safely clean an aquarium before setting it up?

If you purchased a new aquarium, simply rinsing it out with plain water will be enough. When you get a "new" used aquarium, the most important thing to remember is what not to do. Do not clean the aquarium with soapy water or with cleaning products. You should simply clean the aquarium with hot water. If you wish, you can mix some non-iodized salt in the water you are using to clean the tank. You may want to use a clean razor blade to scrape off any algae or calcium clusters which you can't remove from the glass with water alone.

Q. Should I rinse my gravel before adding it to the aquarium?

Yes, you should remove the gravel from the bag and place it in a clean bucket. Run water over the gravel several times to remove any dust that may be on it. Then hold the gravel in place and empty the water from the bucket. A household colander can help speed the process.

Q. How do I get rid of the white build-up on the tank, filters, etc.?

The white build-up is caused by calcium deposits or minerals found in water. You can use vinegar to remove the build-up. If you don't have vinegar, you could also use lemon juice, although vinegar works best. Just put some on a clean cloth and rub over the calcium deposit. Rinse with warm water when you are finished. If you’re setting up an old aquarium, you will also need to clean the aquarium hood and possibly the light strip. In addition, the light strip will need to be tested. If the bulb is black on both ends, you will need to replace it.

Q. How many hours should I run the hood light?

In general, you want to replicate a natural day and night-time cycle. Turn on the light when you get up in the morning and turn off the light in the late evening. Most species of fish will need the light on for 10 – 12 hours. You can simplify this task by using a simple household timer to turn the lights on and off. If you begin to experience a build up of algae, however, one of the first things you can do is cut back on the amount of time the light is on.

Aquarium Product Setup

Q. What should I do if my new Tetra Whisper® Power Filter is not working?

Be sure there is water in the pump chamber -- if you don’t add water to the pump chamber, the filter will pull in air. Also, take care with how much water is in the aquarium. Most filters need the water level to be about one inch from the lip of the filter, and a shallow tank may prevent the filter from working. Finally, make sure your bubble walls and/or air stones are not directly under the intake tube. If bubbles go up the main tube, it will cause a rattling sound and may stop your filter from working.

Q. My new Whisper® Power Filter starts to work, is noisy, or shuts off. What should I do?

This is often a problem with the impeller. Make sure the magnet and the white blades are connected as one piece. If they are separated, you will need a new impeller. This separation is covered under our 2-year warranty. Another problem that may occur with the impeller is sand. Tetra Whisper® Power Filters will not run properly in an aquarium containing sand. The sand gets between the magnetic impeller assembly and the Energizer®, preventing it from turning. You could possibly replace the sand with gravel or purchase a mesh net from your local pet store. Place the mesh net (or a piece of panty hose) on the strainer. Your filter will still pull out waste but it will not pull up the sand. Gravel is the preferred choice over sand in a freshwater aquarium.

Q. Does my Whisper® Power Filter put oxygen in the water or do I need an air pump?

Tetra Whisper® Power Filter cleans the water and adds oxygen. As the water flows back into the tank, it breaks the surface, creating turbulence that adds oxygen to the water. It works like a waterfall. It can only benefit your tank to have extra oxygen, and the Whisper® Power Filter is all you need.

Q. Is the Tetra In-Tank Filter submersible?

The Tetra In-Tank Filter is completely submersible. The pump is a modified pond pump that has been in production for many years, and is perfectly safe to submerge.

Q. Do Tetra Air pumps come with airline tubing?

The airline tubing, air stones, check valve, etc. are all sold separately. The pumps are sold with a “t” connector. This will allow you to combine two ports into one port. If you have a pump with two ports, the pump will be very loud if you do not put airline tubing on both ports.

Aquarium Equipment Problems

Q. What should I do if my Whisper® Air Pump is not producing air or is very loud?

An air pump that loses power or gets very loud may have a bad rubber diaphragm. These parts are located inside the pump. Just remove the screws on the bottom of the pump to open it up. The round rubber disk is the diaphragm. Each pump has a lifetime-limited warranty for manufacturing defects. Water damage does not fall under the warranty. So make sure you are using a drip loop and in-line check valve. If you cannot do this, make sure the pump is higher than the aquarium. Also, the pump is for indoor use only. The rubber parts, such as the diaphragm, are considered a “wear and tear” item. The life of the rubber parts depends on the application. For example, a diaphragm running a one-inch air stone will last much longer than one running a twelve-inch bubble wand. These parts will need to be replaced over time and are not covered by the warranty. 

Many replacement parts are available in our Tetra online product catalog. Check there for the ones you need. If you have questions about replacement parts, please call us at 1-800-423-6458 between 7:00 a.m. and 9:00 p.m. EDT.

Q. What can I do if my Whisper® Power Filter has stopped working?

Sometimes, the magnetic impeller assembly can become clogged with debris. To clean off fish waste, mineral deposits, etc., you will need to take the magnetic impeller assembly out of the filter. Take the rubber end cap pieces off the top and bottom. Slide the magnetic impeller assembly off the metal shaft and place both the impeller and the metal shaft in white vinegar. The metal shaft and magnetic impeller assembly should be soaked side-by-side. Do this for two hours and then rinse them in warm water. You can now put the magnetic impeller assembly back together. Check to be sure the magnet and the white blades are connected as one piece. If they have become separated, you will need a new impeller. This separation is covered under our two-year warranty. If you need a new impeller or another part, you can buy replacement parts directly from Tetra.

Q. My aquarium heater is not working properly, what can I do?

If your heater is not maintaining the correct temperature, make sure it has been in operation for 36 hours. The heater will slowly raise or lower the temperature over time. This will prevent a large temperature swing that can shock the fish. If it is still not working properly, please contact Tetra. Please note: never remove a heater from the water if it is still turned on. Unplug it first, let it cool, and then remove it.

Aquarium Fish Setup

Q. What types of fish should I add to my aquarium?

There are a variety of fish you can add to your aquarium. As a rule, tropical fish and goldfish should not be mixed. Also keep in mind the size a fish will reach as it matures. As fish grow, they may outgrow your tank. The type of fish to choose will depend on the size of your aquarium and the temperament of the fish. There are community, semi-aggressive, and aggressive fish. If you mix in an aggressive fish with a community fish, it could mean the death of your new fish. Your local pet store can help you select the right fish.

Q. When can I add fish to my new aquarium?

When you first set up your aquarium, it is recommended you run your filter, heater, and air pumps for 24 – 48 hours before adding your fish. This will allow the heater to stabilize the temperature and ensure that all equipment is working properly. After this 24-48 hour period, you can add your Tetra AquaSafe® to the water, and then immediately add fish. When you do add your fish, float them in a plastic container for 20-30 minutes. This will allow the water temperature in the bag to be the same as the water temperature in your aquarium. After three to four weeks, you can begin introducing new fish at a rate of one to two fish per week. Just keep in mind that you should have one gallon of water per one inch of (mature) fish. Have three gallons of water per one inch of goldfish.

Q. What types of fish should I add to my aquarium?

There are a variety of fish you can add to your aquarium. As a rule, tropical fish and goldfish should not be mixed. Also keep in mind the size a fish will reach as it matures. As fish grow, they may outgrow your tank. The type of fish to choose will depend on the size of your aquarium and the temperament of the fish. There are community, semi-aggressive, and aggressive fish. If you mix in an aggressive fish with a community fish, it could mean the death of your new fish. Your local pet store can help you select the right fish.

Aquarium Water Problems

Q. My water is cloudy. How can I clear the water?

The cloudiness you are experiencing is probably one of two things.
First, overfeeding your fish can cloud your water as the uneaten food is allowed to decompose. At each feeding you should feed no more than what your fish can eat in one to two minutes. Overstocking the tank (too many fish) also can cause cloudy water. Excess waste, like excess food, gives off ammonia and nitrites. You should have 1 gallon of water per one inch of (mature) tropical fish. Have three gallons of water per one inch of goldfish. It is best to buy the largest aquarium you can afford. The larger the aquarium, the more waste your aquarium can handle before it becomes a problem to your fish.

Second, your aquarium could be experiencing what is known as “new tank syndrome.” When you set up a new aquarium or when you carry out a large water change, it is very natural for your water to become cloudy as part of the system’s normal biological cycle. The reasons for this are fluctuations in the nitrogen cycle, and the release of gases in solution as the result of an increase in water temperature. A water change of 50% or more will help by restarting the cycle. Also, be sure to monitor and change your filter cartridge on a regular basis. A good rule of thumb is at least once a month, or twice a month if you have a heavy fish load or if you have fish that produce more waste such as Goldfish or Cichlids.

Have a pet store test your water, or you can purchase Tetra EasyStrips™. High ammonia and nitrites would indicate excess food or waste. A 25% water change will bring down these levels until you can fix the problem.

Also, be sure your filter is properly rated for the size of your aquarium.

Q. My water is green!

This is due to algae in the water. A few things can cause excess algae. The first thing is direct sunlight on the tank. Make sure your aquarium is positioned where this can’t occur. The next thing is excess nutrients. We suggest you have one inch of fish per one gallon of water. For example, a 10-gallon tank should have only 10 fish that are one inch each. More than this will elevate ammonia and nitrite levels. As a result, the algae will have plenty to feed on. To solve the problem of green water, do a 50% water change. Scrub down the insides of the glass with a magnet scrubber or scraper (but please…no soap!). Remove any artificial plants and ornaments, and pour boiling water over them. Wait one whole day, then do a 25% water change. Cut back on your feeding. Your fish should eat all the food in two minutes or less. This should help get your tank in good shape. You may also install a UV clarifier. This is installed in-line with a canister type filter that is placed in a cabinet or stand beneath the aquarium.

Q. My water has a very bad smell to it. How can I eliminate the smell?

The first thing you should do is test your water with Tetra EasyStrips, for high ammonia and nitrite levels. A bad smell is usually a sign that excess waste is in the tank, and usually excess food. To correct the problem, change out 50% of the water, wait one whole day, and then change out 25% more of the water. Make sure when you feed the fish that they are eating all the food in two minutes or less. You should have one gallon of water per one inch of tropical fish. Have three gallons of water per one inch of goldfish. Make sure the water is properly filtered as well. Ne sure to use Tetra AquaSafe® when replacing water to make your tap water safe for your fish.

Q. How much Tetra AquaSafe® do I add per gallon of water?

You should add eight drops of Tetra AquaSafe® per one gallon of water. For example, a two-gallon aquarium will need 16 drops of Tetra AquaSafe®. The 3.3-ounce size has a dropper built into the bottle.

Q. Why should I test the water in my aquarium?

In nature, waste products from decaying matter, fish waste, and other animal waste are naturally filtered. The harmful ammonia and nitrites are removed by bacteria and plant life. The substrate at the bottom of a body of water will absorb harmful chemicals and decaying matter like a natural filter. The actual size of rivers and lakes will keep water healthy for animals. The larger a body of water, the less lethal any harmful chemicals will be to its inhabitants. In an aquarium, the natural filtration is replaced by equipment, which filters the water. The larger the aquarium you own, the easier it is to keep the water balanced and healthy. To ensure the ammonia and nitrite levels have not reached harmful levels, be sure to test the water.
To understand how filtration occurs, one needs to understand the cycle. Fish waste and other decomposing material will produce ammonia. In high quantities, this chemical will kill animals in an aquarium.

A new system will not have nitrifying bacteria present. Ammonia levels and then nitrite levels can reach deadly amounts. If this happens, partial water changes will bring levels down without destroying all of the nitrifying bacteria. This will only last about four to six weeks before the tank “cycles.” Or, you can add Tetra SafeStart® to your new aquarium. SafeStart® accelerates the establishment of the bio-filter in newly set-up freshwater aquariums. The live bacteria start working immediately to provide a safe and healthy environment for your fish without the long wait. SafeStart can also be used after a water change, when adding new fish or after medicating.

Elevated levels of ammonia and nitrite should not occur in a “cycled” tank. Causes of elevated levels in a mature system would indicate overstocking or over-feeding, and should be corrected immediately.

Fish Tank Maintenance Tips

Q. How often should I change the filter cartridge on a Power Filter?

The cartridge should be changed at least once a month. Or when you see a noticeable decrease in water flow.

Q. How often should I change the water in my aquarium?

You should do a 25% water change every two to four weeks. There is no reason to remove the fish during the water change. Make sure you stir the gravel or use a gravel cleaner during the water change. When adding water back in to the aquarium, use Tetra AquaSafe® to remove the chlorine and chloramine. Try not to change more than 50% of the water, because this will remove the beneficial bacteria and can cloud the tank.

Q. Can the Power Filter cartridge be rinsed off and reused?

No, it should not be reused. The cartridge should be changed at least once a month or when you see a noticeable decrease in water flow.

Q. Does the Whisper® Power Filter put oxygen into the tank?

The Tetra Whisper® Power Filter cleans the water and puts in oxygen. As the water flows back in to the tank, it breaks the surface, creating turbulence that adds oxygen to the water. It works like a waterfall. It can only benefit your tank to have extra oxygen, and the Whisper® Power Filter is all you need to get started.

Aquarium Fish Maintenance

Q. How often do I feed my fish?

You should feed your fish two to three times daily. A few flakes per fish is sufficient. The fish should eat all the food in two minutes or less. Overfeeding can cloud your water and harm your fish.

Q. What do I feed my fish?

What you feed your fish will depend on what type of fish you own. If you have tropical fish, they can eat TetraMin® Flakes, Pro Tropical Crisps®TetraMin, TetraColor®, etc. Tetra has provided  categories of food for specific fish. For example, goldfish, cichlids, and bettas have their own specific foods for their specific needs.

Q. My fish has turned dark black or has its color washed out. What is happening?

This could be a sign of stress. This is common for fish that have just been added to an aquarium. It can also happen when one fish is harassing another. Otherwise, test the water levels with Tetra EasyStrips™  for ammonia, nitrite, nitrate, high pH, and incorrect temperature.

Q. My fish has a cloudy looking eye. Why?

The cloudy eye could be an injury from netting the fish. You should treat the injury as a bacterial infection. Your local store should have a medication available. If you have a UV clarifier, leave the ultraviolet light on to help prevent the spread of the disease. If you suspect your fish is ill, check out our guide on how to spot fish illnesses.

Q. My fish has torn or shredded fins. What can I do?

It sounds like your fish has fin or tail rot. You should test your water for high ammonia and nitrite levels. This can lead to the disease. Treat this as a bacterial infection. Your local store should have a medication available. If you have a UV clarifier, leave the ultraviolet light on to help prevent the spread of the disease. If you suspect your fish is ill, check out our guide on how to spot fish illnesses.

Q. My fish is covered in tiny white spots, like it has been sprinkled with salt. What can I do?

It sounds like your fish has the parasite called Ick. This parasite is found in all aquariums. It normally cannot attach to the fish unless the fish is in poor health. You should test your water for high ammonia and nitrite levels. Your local store should have a medication available. Keep your aquarium lights off to disrupt the parasite life cycle. Increase your aeration and elevate your temperature to 85°F, at a rate of one degree every five hours until you reach 85°. Treat for 10 days. If you suspect your fish is ill, check out our guide on how to spot fish illnesses.

Q. My fish is darting around the tank and seems hyperactive. What is going on?

If you did not use Tetra AquaSafe® to remove the chlorine, the fish gills are being burned. This will cause the fish to dart around the tank. If it has been fewer than 24 hours since you added the fish, add Tetra AquaSafe® now. After 24 hours, the chlorine will evaporate out of the system, but the damage will already be done. This behavior can also be caused by fish fighting. Make sure another fish is not harassing the distressed fish. If this is not the case, test the water levels for ammonia, nitrite, nitrate, high pH, and incorrect temperature.

Q. Why is my fish scratching against the rocks?

This behavior could indicate a parasite. It may be Ick. This parasite is found in all aquariums. It normally cannot attach to the fish unless the fish is in poor health. You should test your water for high ammonia and nitrite levels. Your local store should have a medication available. Keep your aquarium lights off to disrupt the parasite life cycle. Increase your aeration and elevate your temperature to 85°F, at a rate of one degree every five hours. Treat for 10 days. It could also be gill or skin flukes. Ask your local retailer for a proper medication. If you suspect your fish is ill, check out our guide on how to spot fish illnesses.

Q. Why is my fish breathing rapidly?

Rapid breathing could indicate a number of things. It could be stress from traffic in your home, or from a harassing fish. New fish will breathe rapidly from the shock of being transported. You should also test your water for high ammonia, nitrate, pH, and nitrite levels. These can be toxic to fish and cause stress. Also check for parasites or disease. If you suspect your fish is ill, check out our guide on how to spot fish illnesses.



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