The Cobalt Aquatics EXT aquarium canister filter is another reputable option for a canister filter that has been on the market for a few years. The Cobalt EXT uses an external powerhead to drive the filter, rather than having an integrated drive pump.
One unique characteristics is the ability to disconnect the input and output tubing from the canister to allow you to clean the filter and keep circulation going. The filter itself, features an easy-to-open lid and a four-stage filtration trays.
- 1st stage sponge filter
- 2nd stage activated carbon
- 3rd stage ceramic rings
- Final 4th stage finishing floss
The Cobalt EXT has a maximum flow rate of 210gph that is rated for tanks up to 55 gallons. Some online reviews praise the simplicity and quiet operation but may feel you’re pushing it for a medium to heavy stocked 55 gallon tank. Since it is an external powerhead, you could up the size a bit, but it could impact the filter’s effectiveness by pushing water through too quickly.
Cobalt Aquatics EXT aquarium canister filter retails for under $150.