Redearslider.com :: Filter Types

There are a variety of filters, media and attachments that you may use. A multi-stage filtration system will allow you to add mechanical, biological and chemical media options. Turtle keepers commonly use power filters, internal filters, canister filters and pond filters. Your turtle’s size and quantity, tank size, enclosure type and tank location will determine the best type of filter for your needs. Be sure to avoid filters marketed for turtles, like the Zoo Med 501 Turtle Filter. While there are no technical problems with this type of filter, they are not powerful as similarly priced filters.

Remember that a filter should be rated 3 times greater that what it is recommended for. This is to accommodate the greater amount of waste turtles tend to produce. For example, a Filstar XP3 canister filter is intended to be used for aquariums of up to 175 gallons but should be adequate for a RES in 60 gallons of water.

Filters need regular cleaning for maximum efficiency. Mechanical media needs frequent cleaning or replacement since they may become clogged. Clogged filters cannot circulate water efficiently and will deprive biological media of oxygen. Colonized biological media should only be rinsed in tank water to preserve the nitrifying bacteria. Chemical media, such as carbon, need to be replaced since they become saturated with the impurities they are designed to capture.

Reference: Filter Specification Chart

Internal Filters

Internal filters offer decent mechanical filtration for small tanks and are easy to clean. There are 2 types: ones that are completely submerged and another that is partially submerged. Either will not provide adequate biological filtration (even those described as bio filters or multi-stage filters). Though they are inexpensive and easy to find, they also take up valuable room inside the tank.

Hang On Tank (H.O.T.) / Power Filters

H.O.T. filters (a.k.a. hanging or overflow filters) are good at mechanical filtration, easy to clean and easily accessible. These filters hang on the side of tank, so they might need extra bottom support if they are being used on a plastic container. They might obstruct other equipment such a tank hood or screen but are generally not a problem. They are not as large as their canister filter counterparts and some have limited room for biological and chemical media. The AquaClear 110 is a particularly capable power filter with a generous foam pad and room for another type of media.

Power filters do not have output tubes and nozzles but rely on the water flowing out which is often regarded as a “waterfall”. This does not generate optimal water circulation in larger tanks. Because water levels in turtle tanks are not always at the maximum level, these filters will produce more splashing and related noise. This can be reduced in many cases with a simple DIY fix by extending the lip or by adding a flap. Low water levels may also make it difficult for these filters to prime themselves after power loss and they may become damaged by running dry.

Canister Filters (Recommended)

Canister filters are the preferred choice for indoor turtle keepers. Though they are more expensive than the other types of filters mentioned in this section, they do provide excellent mechanical and biological filtration. They also have room for other media options for further and future customization. Larger canister filters have 3 or 4 different compartments for storing different types of media.

Some canisters come with different output options such as adjustable nozzles and spray bars. They also have flexible tubing that might make it easier to attach to a tank in a difficult location. They do have more parts so it may take longer to thoroughly clean. These filters will stay primed during power loss and resume normal operation when power returns. Their overall versatility and performance can provide the best filtration for your turtle’s habitat.

Pond Filters

There are various pond filter designs out on the market. For indoor use, you should consider what is called an external filter. These are similar to canister filters and they offer multi-stage filtration but will require a separate pump. These filters come with optional UV sterilizers that are unnecessary to use with turtles.

Wet/Dry Filters

Wet/dry filters come in various power filter designs and their underlying principle is to promote maximum nitrification by having the bio media rotate between being in water and exposed to air. By introducing more oxygen to the biological media, the filter has the ability to decompose ammonia and nitrites much faster. This efficiency does not necessary qualify this filter as superior since mechanical filtration and water flow may not be comparable to a canister filter. The Penguin BIO-wheel is an example of wet/dry biological filtration and shares the same benefits and drawbacks of other power filters. Since turtles produce more waste than fish, you can expect to clean this more frequently.

Other Filter Types and Accessories

Corner filter: These small filters usually come with a 10 gallon tank kit. They are not adequate by any means or measure.

DIY filter: Filters are fairly simple in design and some experienced keepers choose to build their own filters. Most of these filters follow design principles of canister filters with the addition of more powerful motors and greater media capacity.

Prefilter: As an attachment, a prefilter is an additional foam pad is added to the intake. This provides mechanical filtration for a primary or biological filter. Like any mechanical media, prefilters will clog with waste without regular maintenance. There is also prefilter media, which help capture large debris and reduce water flow. These are not needed for turtle setups.

Surface skimmer: An attachment designed to help improve oxygen exchange and skim the surface for proteins. These may not be effective for turtle habitats because turtles often generate too much activity.

Sump: A reservoir below the tank in which water from the main tank is drained into. The sump may contain accessories such as filters, heaters and thermometers. A pump or filter returns the water back to the primary tank. Usually used by fish and reef hobbyists, this type of filter increases water volume and keeps the primary tank visually appealing.

Undergravel filter: This type of a filter mainly serves biological filtration. It is not suitable for turtles because of its reliance on a gravel substrate. It does not provide adequate mechanical filtration and turtles will likely dig up and disrupt the bacteria colonies.

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