# under gravel filter...



## daniel89 (Nov 28, 2009)

Christina here...

I bought my brother and my dad a new betta each in their own 2 gallon tanks with an under gravel filter. I don't know anything about this type of filter though. Does anyone know how it works and how I need to maintain it etc... Any information about it would be helpful!

Thanks!


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## Guest (Dec 31, 2009)

Well there are 2 types of undergravel that I am aware of. One air pump powered and one powerhead powered. Which one is the one you got?


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## emc7 (Jul 23, 2005)

You can run any UG with either a powerhead or an air pump if you have the adapters. The ones with 1" upright tubes are easier to adapt to powerheads than the ones with little upright tubes. They work by pulling the water down through the gravel, which acts as a biological filter media. Because of the large surface area of gravel, even a little bit of flow gives a lot of biological filtration. Some people (COM) thing they are horrible. But they are a proven technology and very cheap and not bad looking for an inside-the-tank filter. 

But they are biological only. All of the waste that gets pulled into the gravel (too much flow will suck down the food before the fish can eat it) stays in the tank until you take it out. So maintenance is important. Every water change, use a gravel-washer on your siphon hose to clean gunk out of the gravel. And periodically take all the gravel out of the tank, lift up the UG plates and suck up all the waste thats under them. Also clean the uprights with a long brush. This is a lot more work that changing a filter cartridge in the hang-on-back. Though, IMO, if you have any substrate in a tank, you should be cleaning it regularly. If you slack off, you will get high nitrate in your tank (all that trapped waste slowly decays)

There are some side benefits to UG filters, like the flow through the gravel should keep anaerobic pockets from developing in the substrate. The plates protect the bottom of the tank from dropped rocks. The uneven plates allow fish to dig out entrance tunnels under things like upside down flower pots. 

There are drawbacks, too. The extra work cleaning the gravel. The tendency of nitrates to climb (I would avoid them in tanks with sensitive fish) which can make pH fall. The occasional fish down the upright tube. The amazing ability live plants have of tangling their roots in the plate. Plants will do good in a tank with UG (water, waste filled water for the roots), but you can't move a plant without cutting off some roots. And when you lift the plate to clean under, all the plants will come with. I would say put any plants in a tank with a UG filter in pots. 

In a betta tank, I bet you have the small upright type. You have 2 tubes attached to the plate. A small, rigid tube attached to an air-line and a larger rigid tube. The small tube goes in or next to the big tube and the air comes out at the bottom of the big tube. The air pulls the water up the upright and that water is replace by water flowing down through the gravel. I think is you do weekly gravel-washings with large water changes, your bettas will thrive. You can get decent filtration with just a slow stream of bubbles.


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## lohachata (Jan 27, 2006)

i have been using undergravel filters for more than 35 years..they are my favorite filter.emc is right..you probably have the small lift tubes..so use a small air pump..
although plant roots may get tangled in the plates ;it is ok to snip them.
the only time i have ever vacuumed the gravel every week was when i fed heavily.otherwise only once a month.for this small tank with only 1 or 2 fish in it ; you shouldn't have to do a tear down but once or twice a year...
while UG filters are mostly biological type filters ; they are also mechanical..larger particles get trapped between the gravel..then smaller and smaller pieces get trapped...after awhile the filtration will be so efficient that the water will almost look like it isn't there.


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## Guest (Dec 31, 2009)

I didn't read any of emc's post, so this might have alreadybeen said, but:
Just get one of those little needle valves meant for air pumps. If the flow of air is too great it will not work as well as it could.


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## jones57742 (Sep 8, 2007)

lohachata said:


> you shouldn't have to do a tear down but once or twice a year...


loha:

Why would you want a filter which requires this? (serious here - no humor).

TR


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## Guest (Dec 31, 2009)

Every filter needs to be cleaned, and with this type it is a bigger job, but it is okay because it is only needed every 6-12 months.


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## emc7 (Jul 23, 2005)

Don't your tear up a tank that often anyway? I do, to catch fry, clean the gravel, etc. If you have gravel without a UG, its almost as big a job to clean. So why waste all that potential bacteria surface? 

I have mixed feeling about UG filters. The are more work, but I've never had one "fail" completely. A canister or hang-on-back can have its pump fail or clog its intake and be totally useless. A UG usually has some flow even when the fish more all the gravel off the plate and gravel sticks to the powerhead intake. I use them in 55s with African cichlids and they make a good base for a rockpile (uneven, not slippery like glass bottoms of tank). The "UG filters lead to sky-high nitrates" criticism is well-founded, though. I do see higher nitrates in those tanks (though they are also the most heavily stocked tanks). In the basement, I go for giant sponge filters, but in the living room , UG + canister for quiet, discreet filtration.


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## aspects (Feb 1, 2009)

jones57742 said:


> loha:
> 
> Why would you want a filter which requires this? (serious here - no humor).
> 
> TR


exactly.

UGF are an outdated and boarderline useless filter. while they had their place 20+ years ago, they have been replaced by efficient filters. even if youre looking for something cheap, there are other filters that are cheaper and more effective. 
sponge filters are extremely cheap and do not require the extra maintenance of a UGF. also, they can be used with sand substrate, and will not effect plant rooting. 
box filters/corner filters are essentially the same as a UGF, but it sits on top the substrate for easy removal and cleaning. again, all the filtration of a UGF, none of the hassle. 

UGF were the main type of filtration a couple of decades ago because at the time canisters were extremely expensive. these days with the advancement in filtration technology, and the materials used, canisters (and HOB filters) are available to consumers at a reasonable price, and offer actual filtration unlike a UGF which barely offers bio-logical filtration, but no mechanical filtration. 


unfortunately, with a 2g tank, your options are pretty limited. unless you are willing to go out and find a mini filter, or DIY something, the UGF is probably the easiest way to go . even the mini sponge or box filters will take up a good amount of your tanks volume.


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## aspects (Feb 1, 2009)

emc7 said:


> Don't your tear up a tank that often anyway? I do, to catch fry, clean the gravel, etc. If you have gravel without a UG, its almost as big a job to clean. So why waste all that potential bacteria surface?
> 
> because a proper filter will house your bacteria in the bio media. the flow and aeration of a proper HOB (not the useless cartridge type) or canister filter offer a better habitat for colonization.
> 
> ...


in the end, UGF are really more of a hassle than theyre worth. (and what theyre "worth" is just about nothing). 
i, like you, prefer to use large sponge filters. i use them in my grow out and fry tanks. they provide all the filtration of a UGF, but the maintenance is 100x easier and theyre cheaper to boot.


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## daniel89 (Nov 28, 2009)

the UGF has a air pump and all that. i just have to teach my dad and brother how to clean it out and all. my dad already has a salt water tank though so it shouldnt be too hard to teach. 

how much of a water change do you all recommend? about 30% once a week?


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## jones57742 (Sep 8, 2007)

emc7 said:


> Don't your tear up a tank that often anyway?


No.

I believe that my question derives from two conditions:

1) My wet/dry filtration which is virtually maintenance free; and

2) My improved substrate. With 2" of laterite overlaid and underlaid by 1" of 3/8" gravel "tearing down" would be a disaster. 




emc7 said:


> So why waste all that potential bacteria surface?


In my world just adding another bag of sintered glass, ceramic toroids, etc ...

TR


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## daniel89 (Nov 28, 2009)

any opinions on how frequent water changes need to be? i was thinking 30% once a week and then 100% once a month.


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## emc7 (Jul 23, 2005)

That sounds fine. Bettas are pretty tolerant, so you go 50% with no issues. I would take enough out to siphon a good bit of the crud from the gravel. In a little tank, that might be most of the water even if you use a "mini" gravel washing siphon like this http://www.amazon.com/Lee`s-Aquarium-Gravel-Vacuum-Cleaner/dp/B001EUJJFM/ref=pd_sxp_f_pt .

Or you could change a little water every week and once a month or couple months dump the gravel in a strainer and rinse it the sink. Of course, that would trigger at least a mini-cycle, so it would have to be pretty bad to be worth it.

Sorry about the hijack. Every mention of UG filters seems to trigger a rehash of the debate. IMO there are better filters, but since any filter is better than none, I have to argue with the "UG are worthless" group.


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