Undergravel Filters

[Audfish]

I was wondering if anyone could tell me how an undergravel filter works. I have one in the tank with my little office pet, Bovie. It seems that all the debris just sits under the plate and doesn't go anywhere. Is that really what is supposed to happen or am I missing a piece? It basically looks like a black plate with holes stuck to a clear tube that doesn't go anywhere.

 

[Viettxboii]

thats basically it... id reccomend putting some fitler floss in between the place and hte gravel ,and do gravel vacs to keep the substrate clean, and suck out hte debree.

 

[squarefish]

I take it you have a filter pump in there as well... The water will be drawn down through the gravel under the plate and sent up the tube to flow out of a spray bar or similar.

 

[LakeyGal]

Got this info from a site I linked to earlier tho there are a lot of valid opinions out there.

Under-Gravel Filters: This was the first true biological filter invented for the aquarium. The gravel in an aquarium is suspended above one or more plastic plates, which are equipped with "lift tubes" that extend vertically from the bottom to the water surface. Air is pumped into the bottom of the lift tubes and rises up the tubes, carrying water with it. This causes water to flow down through the gravel and up the lift tubes back into the aquarium. Instead of air, power heads may be used to drive the filter. Power heads are submersible pumps that are mounted at the top of the lift tubes and pump water directly up the tubes and out into the aquarium. Power heads are a much better means of operating an under gravel filter, increasing flow by several hundred percent.

Undergravel filters are inexpensive, and though they require monthly vacuuming of the gravel, most aquaria need this anyway. They do a great job in freshwater tanks. In saltwater aquaria, which has much lower levels of dissolved oxygen, undergravel filters should not be used, as the submerged aerobic bacteria in the gravel are competing directly with the fish for oxygen. It was this fact, that led to the invention of the wet-dry filter in the 1980s. The use of aerating power heads helps eliminate this problem to some extent.

 

[Davidtq]

The interesting thing with an undergravel filter is that instead of being a filter under the gravel, the gravel IS the filter, giving a huge amount of filter media. Despite them being out of fashion and even I havent used them in years they are in fact a good solid form of filtration that has been used for many years without any more problems than any more recent forms of filtration.

I think I spent too many years using them though, these days I cant stand the look of gravel and uplifts and bubbles in the corners, I prefer a sand substrate and well hidden external cannister filters etc. But the under gravel filtration idea does work very well.