Goldfish Care Guide

It’s very easy to feel overwhelmed by all the choice in the aquarium filter market, which is no doubt just how the manufacturers like it. Confusion equals opportunity in retail!

But fear not, aquarium filtration is much more simple than it initially appears. There are four basic types of aquarium filter commonly used in goldfish tanks today :

• Undergravel filter: This is a perforated plate that sits beneath a level, 2-3 inch layer of gravel at the bottom of the fish tank. Water is drawn through the gravel via the plate by upright airlifts, which are in turn powered by either bubbles from an air pump or by small submersible devices called powerheads. The gravel acts as a mechanical filter, and after a period as a biological filter, too.
  • Advantages: Cheap, fairly discrete, and work well provided your tank isn’t overstocked.
  • Disadvantages: You’ll need more gravel than would otherwise be the case, especially as some fish dig, and this reduces the capacity of your tank. The gravel must be kept clean using a plastic gravel cleaner, which can make your aquarium chores more tiresome. Air pumps can be noisy. Finally, undergravel filters can struggle to cope with hearty eaters like goldfish.

• Internal power filter: These are small electrical units that sit submerged in the corner of your fish tank, secured to the glass with suction cups. Water is sucked into the bottom of the filter and passed through a sponge before being squirted out the top. The sponge traps debris, and in time also becomes a very capable biological filter. Some advanced models include a special compartment for activated carbon.
  • Advantages: Economical and unobtrusive yet surprisingly powerful, internal power filters are a good choice for goldfish aquariums. Quiet in operation, and there’s no danger of leaks.
  • Disadvantages: A little more expensive than the cheapest undergravel filter and air pump combination. Also, internal filters aren’t easy to disguise, and cleaning them means disturbing your fish.

• External power filter: Typically about the size of a large soda bottle, an external power filter sits underneath or to the side of your aquarium. Two tubes connect the power filter to the tank. One tube draws water in from the aquarium; it’s pumped through the power filter, and the other tube then returns the clean water to your tank. Power filters have several compartments inside, enabling you to use special purpose filter media, such as quick change filter floss in the first compartment or activated carbon in the last, in addition to the standard filter sponge.
  • Advantages: Powerful and versatile, power filters don’t take up any valuable space in the tank, nor do they distract from the furnishings. They can be cleaned without disturbing your goldfish, too.
  • Disadvantages: By far the most expensive kind of filter. They can leak if the tubes aren’t fitted correctly or if the unit becomes damaged.

• Hang on the back filter: Some external filters are designed to hang onto the side of the aquarium. Water is sucked in from the tank via an electrical pump. It passes through the filter, and then cascades back into the fish tank.
  • Advantages: Fairly affordable and reasonably powerful, and the easiest of all filter types to clean. The design of the filter inherently causes a lot of surface turbulence, which is great for increasing oxygen levels in the tank.
  • Disadvantages: They can be hard to fit to some aquariums, since they need space either behind or to the side of the tank, and they also need a section to be cut away from the aquarium hood, if present. The waterfall affect can be distracting, particularly in a room you watch television in, and there’s the same potential for leaks as with an external filter.

Provided the model of filter you choose is powerful enough to keep your tank clean, which filter you finally decide on is ultimately a matter of personal choice. Remember that all these filters need to be broken in before the tank is safe for fish. Read our article on how your tank becomes biologically mature to learn more.

Click here to learn more goldfish secrets!