How To Choose The Best Amazon Aquarium Trickle Filters? 2021

Written by Australian Fishtank King in FiltersLast Updated July 20, 2021

Trickle filters are a specialised filtration system, used mainly on quite large aquaria, or to run more than one aquarium.

Trickle filters are biological filters which sit underneath the tank. They consist of a sump, which is simply an aquarium or other water receptacle which contains a biological filter medium, usually bioballs, through which the water trickles. Water is gravity fed into the filter and spread over the bioballs, which are usually held in a partition of the sump, using either a spray bar or drip tray, then is pumped back into the tank from the sump. Since the bioballs are usually at least partially exposed to the air, there is no oxygen limitation and biological nitrification (ie conversion of toxic ammonia and nitrite into nitrate) is very efficient. Trickle filters may be designed with additonal partitions to house mechanical and/or chemical filter media.

Disadvantages of trickle filters are their large size, very high price, and the fact that they must sit below the aquarium. A trickle filter must usually be custom-built to suit the aquarium it will be used on – and the cabinet it will be housed in, where applicable. They are relatively high maintenance as they are prone to evaporation and if the water level is not topped up, the return pump may run dry. Additionally, when used on marine tanks, evaporation must be compensated for to avoid fluctuations in salinity.

Getting water from the tank into the trickle is another thing that must be considered, ideally before the tank and or cabinet are built. There are two ways to do this: Firstly, a hole can be drilled in the tank and bulkhead fitting or a water sleeve used. This must usually be done when the aquarium is manufactured. Secondly, a hang-on self-starting siphon can be used. These automatically stop and restart in case of power failure or when the pump is turned off for maintenance.

Although once hailed as revolutionary, trickle filters are bulky and relatively expensive (3 to 4 times the cost of canister filters) and have now been superseded by modern canisters for home use in many applications. However, trickle filters are often used by stores, breeders, importers and serious hobbyists as they can be set up to filter more than one aquarium, which makes them much more cost-effective.

They are sometimes used on large marine tanks as they allow protein skimmers to be housed in the sump, rather than taking up room in the aquarium. However, the very efficient nitrification provided by a trickle is not alweays desirable, eg in reef aquaria where corals are the main focus. While a trickle will quickly remove ammonia and nitrite, it converts these to nitrate, which is detrimental to corals. Many modern reef keeping methods do away with trickle filters (and sometimes with all forms of traditional biological filtration, especially where no or very few fish are kept) and instead utilise protein skimming and natural filtration by organisms found on live rock and sand. However, a sump without biological media is sometimes still used to house the skimmer and other equipment.

Getting the most out of this filter system:

Plan ahead if you choose trickle filtration: be sure your cabinet is large enough to fit the filter and consider your options for getting the water out of the tank and into the filter. Choose a large enough pump to return water to the aquarium, taking into account the vertical distance from the sump to the top of the aquarium and the turn-over required.

Maintenance should be performed regularly on the spray bar or drip tray, and any prefilters should be cleaned.

Troubleshooting trickle filters

Problem: Filter does not run, ie. impellor is not turning

Possible causes & remedies:

  1. Check power supply, make sure filter is plugged in and turned on at the power
  2. Impellor may be jammed: gentle shaking will sometimes start the pump, but the impellor or impellor well may need to be cleaned.
  3. Faulty/worn impellor or broken shaft: check the condition of the impellor and shaft and replace if needed.
  4. Burnt-out motor or broken wiring: these cannot be repaired, you will need to replace the pump.

Problem: Impellor turns but little or no water movement occurs

Possible causes & remedies:

  1. Restriction of water intake strainer or prefilter: Clean strainer or prefilter sponge
  2. Faulty/worn impellor: Check the impellor, ensure the fan is fixed to the impellor (some spin and click, but should only have about a quarter turn free play), replace impellor if needed.
  3. Lift height too high for pump capacity: the higher up the water must be pumped, the greater the decrease in flow rate. Check the maximum head height, this should be at least twice the height to which you wish to pump.
  4. Air block in pump: Ensure water level is adequate, flush water through pump or shake pump if submerged to dislodge air. Ensure pump intake is away from any source of bubbles.
  5. Restriction of flow by outlet hose or attachments: if the pump is attached to a hose make sure it is of adequate diameter as narrow hose can resrict flow. Clean debris from the hose or other attachments with a flexible brush or pipe cleaner if clogged.

Problem: Filter produces excessive noise

Possible causes & remedies:

  1. Faulty/worn impellor or shaft: check the condition of the impellor and shaft and replace if needed.
  2. Restriction of water intake strainer or prefilter: Clean strainer or prefilter sponge.
  3. Air being drawn through pump: Ensure water level is adequate and pump is away from sources of bubbles

Troubleshooting trickle filters

Problem: Spray bar does not turn

Possible causes & remedies:

  1. Restriction of water flow: clean plumbing and spray bar
  2. Worn or damaged spray bar: replace spray bar assembly.

Problem: Water does not flow down into trickle filter

Possible causes & remedies:

  1. Air-block in self-starting siphon: draw out any air using the air-bleed. Ensure air bubbles are not drawn into the siphon
  2. Blockage in overflow siphon box or pipework: clean pipes and overflow/siphon.

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