Using undergravel filter

[avatar0810]

I've been thinking about adding a UGF to my tank as it was suggested to me that it would be useful. I am already using a top fin 10 gallon power filter and ther person that suggested it said I could run the UGF using my power filter. I'm not really clear on how a UGF works. Could someone give me a thorough explanation of how they work?

This is the one I've been looking at. http://www.drsfostersmith.com/Product/Prod_Display.cfm?pcatid=24994

 

[DrRob]

If the tank is set up then adding an UGF is going to be hugely disruptive. There are better ways to over filter if that's what you're after.

 

[avatar0810]

I appreciate the advice and my tank is already set up. I'm still interested in how an UGF works though.

 

[Byron]

I appreciate the advice and my tank is already set up. I'm still interested in how an UGF works though.

The principal behind an undergravel filter is that the entire substrate is the filter media. A plate sits on the bottom glass of the tank, covering the entire area, with a layer of gravel on top. Water is drawn down through the gravel and up via lift tubes at the rear corners. Air is used to do this, whether with air stones at the base of the uplift tubes (connected to an air pump via tubing--as shown in the linked model) or a power head at the top of the uplift tubes.

Gravel has to be the substrate as sand is too fine. Sand is a better substrate for some fish, so right off you have an issue just with that. The detritus is pulled down through the gravel and collects under the plate. Cleaning this out is not always easy without tearing down the tank. And if the power should go out for any length of time, the gravel bed can turn anaerobic very quickly, since the detritus is within the gravel along with the aerobic bacteria which can become suffocated. This can easily poison fish.

Live plants may manage, though this is not the best filter with plants. Not so much the pulling down of the roots, but more the unnatural flow of water.

The text in the link is correct, about bacteria and such, but there are distinct limits that are not aspects of other types of filters. I used UG filters for many years, but I would never consider one now, and I have a room of 8 planted tanks.

Byron.

 

[avatar0810]

Thanks for clearing that up. I haven't completely ruled out the possibility of using one in the future but I don't think I'll be using one at the moment.

 

[Toney]

I'm using one in my 55 along with a hob

 

[StevenF]

The problem with UGF available today is air is typically used to move the water. This is a very inefficient way to more water. End result is the flow through the filter is limited. However some people have used water pumps instead of air stones. That generates higher flows through the filter and material is less likely to build up in the substrate.

An alternative UGF design is the reverse flow UGF (or RFUGF) in this design the equipment is the same but water is pumped down under the substrate. The water then moves up through the substrate potentially lifting organic material out of the substrate where it can then be removed with a weekly vacuum.

Air stone powered under gravel filters for small tanks are available but the lower flow limits there effectiveness. As a result they are not very popular. Water pump powered UGF and RFUGF filters for larger tanks are not available from manufactures. SO if you want a water pump UGF you have to make it yourself.

Gravel can and has been used in conventional filter. The bacteria grow on the gravel instead of a filter sponge or some other manufacture filter meterial. Given the size and volume of the substrate and undergravel filter can process ammonia, nitrates,and organics faster than a typical aquarium filter.

And if the power should go out for any length of time, the gravel bed can turn anaerobic very quickly, since the detritus is within the gravel along with the aerobic bacteria which can become suffocated. This can easily poison fish.

It is important to mention that Anaerobic activity can also occur in in conventional aquarium substrates. Anaerobic substrates is not necessarily bad since anaerobic bacteria can process nitrates while the high oxygen level in most aquariums prevent nitrate processing by bacteria. Any thank, regardless of filter type, with a lot of organics can have issues with water quality if power goes out for an extended period of time. Your typical short power outage should not cause any issues.

http://www.firsttankguide.net/ugfcontroversy.php

I think a early ideal setup is a pump powered UGF with a small external container containing the pump, a particle screen to remove large organic particles and the water heater. If wanted phosphate, nitrate absorbers carbon, and UV sterilizers could be located with the pump. This would move a lot of stuff and wires out of the aquarium. This would also eliminate some of the issues related to the traditional UGF

 

[AbbeysDad]

I remember using UGF's some 30 years ago but would not ever consider using one again. The trouble is that unless you religiously gravel vacuum, they become a nitrate factory. I never used a reverse flow UGF, but why bother. Regular filters with bio-sponge material will house all of the beneficial bacteria you'll ever need. Use sand instead gravel for your substrate to keep detritus from getting down under and you will be golden!

 

[ShinySideUp]

I think if I was running a small tank with a few gentle fish in it I might consider using a UGF as there is something inherently relaxing watching the bubbles rise up the tubes and be doing something useful at the same time. My problem would be that I also like a sand substrate and the two are totally incompatible. Why is everything always a compromise [sigh]?

 

[DrRob]

There's always the option of something like a Hamburg Mattenfilter. Does a similar job to the UGF without the plant issues and easier to clean. Does impact on the free space in the tank though.