Types of Filters

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Sherolyn-Basement Bettas

All tanks need to go through something they call a cycle to become balanced and maintain a healthy environment for your fish. Fish will create waste, and as it breaks down it is converted to ammonia. Even a small amount of ammonia is toxic and will kill fish. So how does one get rid of ammonia? To rid your tank of ammonia as well as rid the water of fine particles you need to establish some filtration. Filtration removes the solid waste and the media will also grow bacteria that with convert the ammonia to nitrite and finally to nitrate. There are several types of filters, and some are better than others for your Betta.


One of the more common filters and one that tends to come in aquarium kits is the hang on back, or HOB filter. These filters have a tube that extends down into the water and a pump that sucks water up unto the filter. Once the water enters the filter box it runs through a sponge or filter pad. Either or both will remove solid particles and grow the bacteria you need for removing ammonia. The problem with these types of filters used in a Betta tank is they often have high powered pumps that create a lot of current. Constant currents can cause undue stress on your Betta and may weaken them so they are more apt to succumb to disease. So this type of filter is not the best choice for a betta tank. For a large tank with bigger fish or ones that like a current, these filters are great. Once a month you will want to remove the foam or filtration media and rinse in tank water or dechlorinated tap water. Rinse until the water runs clean again and replace back into the filter.

Box Filter

Another popular filter that often is also packaged with a new tank is a box filter. The box filter is filled with filter media like floss to trap the solid waste. Bacteria will also grow in the floss and aid in ammonia removal. You can also add other types of filter media to encourage more bacteria growth like the Fluval Biomax Bio Rings  shown to the right. Put the rings in the bottom and still top the filter off with the floss. An air hose will attach to the filter and also a pump to drive air into the filter. A current is created through the box pulling your tank water through the filter media and trapping particles. These are great filters for a Betta tank as long as you do not get a big pump that will cause a lot of current. And these filters are also very easy to maintain. Once a month, during your water change, remove the filter floss and rinse in used tank water or water you have treated with dechlorinator to get the solid particles out of the floss. You do not want to use chlorinated tap water as it will kill of the bacteria you have been trying to establish. If you use additional media you just rinse it the same way to remove the solids that are decomposing in the tank.

Under Gravel Filter

Under gravel filters are another type of filter and tend to work best with bigger tanks. This filter is a plate that sits on the bottom of your tank and has holes all over the surface of it. You place several inches of gravel on the top of the plate, and attach tubing to the air stone in the uplift tube. The other end of the tubing is attached to a pump that pumps air into the tube. As the air rises, it creates an upward current that pulls the tank water down and through the gravel. It turns your entire gravel bed into a big biological filter. A gravel bed offers a tremendous surface area to grow a lot of bacteria, but having a lot of the organic matter down in there can actually cause you more problems.  Decaying organic matter will affect your water quality unless you have a siphon tube that will “vacumm” your gravel and remove the funk. As long as you do weekly gravel cleaning, this filter can handle a well stocked tank. Because you are pulling a lot of organic mater into the gravel, this type filter is not the best if you want also to grow aquatic plants. High organic loads in the gavel will cause your plants rot. Because of the maintenance involved with this filter it is best to avoid it’s use with your Betta. 

Sponge Filter

Sponge filters are a popular way to filter tanks of many sizes. They are relatively inexpensive, come in a variety of sizes and are easy to get. The tiny pores in the foam supports the growth of the bacteria used to break down the ammonia, and they also are good at removing fine particles of organic matter suspended in the water stream. Like the box filter, they are easy to maintain. When doing a water change just rinse the sponge in a bowl of tank water or use tap water treated with a dechlorinator until it runs clean. It is a good idea to get in the habit of doing this once a month to keep the filter working effectively. If you see the filter becoming clogged you can also do it more often. For use in a small Bettas tank you want to chose an air pump that will not create a huge current in the tank, so get a smaller pump. For a larger tank, use a large sponge and get a bigger pump.  The larger pump will create more pull to move water through the sponge and increase the filtering ability of the sponge. 

The choice of filter you chose to use is going to depend on several different things. The size of your tank and the boi-load or the number of fish you will be keeping per gallon. For a single small tank with a Betta or two the sponge and box filters work best. If you are breeding Bettas, larger tanks are used for growing the youngsters out. In larger grow out tanks, a big sponge filter is the filter of choice for most breeders. Selecting and maintaining a good filter will go a long way towards keeping your Bettas healthy and their water quality good. 

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