# Undergravel filter debate



## Julie's Julies (Jul 17, 2007)

I have heard many negatives about the undergravel filter, though most books I read still encourage their use. I personally believe biowheels to be a great choice, and I pull up the undergravel filters from the used tanks I buy.

Any thoughts?


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## thepuck (Jul 22, 2007)

I've always used them in tanks 10-55gls and never had any problems. However, there is still the need to provide additional filtration.


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## emc7 (Jul 23, 2005)

They are not for plants (with roots not in pots) and not for sole filtration.  But the UGFs with bumpy plates (I don't like the flat ones) with a powerhead (air-stone are noisy) are a good secondary biological filter. When your hang-on-tank or canister gets clogged or shuts off, they can keep your fish alive. You can take replace the main filter, using the old one to "instant cycle" a new tank and not worry about "re-cylcing" the old one. Of course, a big sponge would do the same thing. Its gets really gross to clean the gravel if you neglect a tank with a UGF, but its no less gross if you have gravel without a UGF.

I don't trust hang-on-back filters (even with bio-wheels) as the sole filtration. It too easy for the intake or filter cartridges to get totally clogged and stop the flow. No water, no filtration. But having 2 hang-on-backs is ok.


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## Apotheosis (Jul 2, 2007)

They're horrible.

The only advantage they have is that they're cheap. Get an HOB instead. If you have the money, get a canister filter. 

The biological filtration you get with an UGF is not worth the hassle (tearing it down), nor the large amount of nitrates it will produce.


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## Willow (Mar 20, 2005)

Yeah, I just pulled mine out because the nitrate levels were crazy high. They're a lot lower now, and the tank seems clearer, too. I still have one of the powerheads going (I had one reverse-flow powerhead w/bio-sponge on each side of the UGF) to prevent a mini-cycle. I didn't pull the other powerhead out right after I removed the UGF, I waited a couple of weeks.


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## Gump (Aug 2, 2006)

IMO worst type of filtration. I will never use it.


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## Guest (Jul 22, 2007)

IMO its always best to have 2 filters on a tank, incase of failure. the BEST way to go is your filter of choice, whether it be canister, HOB, or wet dry, then add a sponge filter as well. the reason for this is that a sponge filter can last a long while in a power outage..where as yoru canisters die of really fast because the lack of oxygen that gets to them. so the sponge filter may just save your fish when the power comes back on


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## emc7 (Jul 23, 2005)

I have to agree with the high nitrates. It agrees with my experience. I still use them in some of my African cichlid tanks. I don't think they are any worse than gravel alone. You just have to suck the crud out to keep the nitrates from popping back up after a water change. And they avoid the dreaded "anaerobic" spot in the gravel. 

Even so, they are such a pain to clean that more and more of my tanks have bare bottoms, plants in pots and sponge filters.

I agree with everything GoodMike said.


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## FishHead (Nov 16, 2006)

I have an undergravel filter on my 30. I have a 100 airpump powering it. I also have a Penguin 60 and just added a topfin 10 (was an extra sitting in a box). I added a powerhead as well and have a large bubble disc on a 75 air pump. 

I havent had any issues with my undergravel filter so far. I think they help with filtration with tanks using larger substrates or medium sized gravel. I think it's a personal preference.


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## Danh (Feb 19, 2007)

I would use a reverse ugf with an overflow system to a sump with very good mechanical filtration... but never use normal ugf.


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## Clerk (Nov 22, 2006)

I once used reverse UGF, until I got hydrosponges, they are sin ugly but work much better.

Now I am buried in all the canisters I have ><


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## Danh (Feb 19, 2007)

I wouldn't use a reverse ugf by itself... Only with a sump. I much prefer wet/dries.


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## foehammer306 (Jul 26, 2007)

They are awful, get anything but them.


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