# Undergravel Filter SmackDown!



## NorthernLights (Mar 2, 2012)

Hi everyone! *waves*

I am trying to figure out why under gravel seem to be so unpopular here, because it has seemed to me for quite a while now that they offer many substantial advantages. I'm going to put my thoughts here (and I DO NOT claim to be an authority at all), in the hopes that the more experienced folks will respond with their thoughts and experiences and shed some light on this topic. For reference, I am considering this in the light of a ~3 gallon aquarium with no live plants.

I am very fearful of using a power filter because of so many stories in which bettas have been somehow killed by them, even with baffles. 

One thing I read frequently is that in order to clean UGF, you have to tear the entire tank apart. For a very small tank, that may be true (although it is also fairly simple), and for the larger tanks, there are "gravel vacuums" which apparently can be used to clean the gravel in the tank, even sometimes with the fish still inside. Now, I have never used one of those, but people who do seem to find them very effective (whether they are using UGF or not). It also seems to me that a person could clean out from under the filter plate by simply putting the vacuum tube on the riser tube and suctioning the waste right out. Thoughts on this?

Another argument I see is that objects in the aquarium can cause "dead spots" in the water circulation. While I can definately see how that is true, I would think that a power filter (especially when baffled to reduce flow rate) would have the same problem, especially since they sit near the top of the tank and waste matter tends to sink to the bottom of the tank. It just seems to me that the filter will mostly end up intaking and expelling the same water nearby. By contrast, it seems to me that a UGF promotes tank-wide water circulation (evening out the temp as well).


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## sarahspins (Sep 5, 2012)

Gravel vacuums don't suck up the waste the accumulates UNDER the filter grid, only what is loose between the gravel itself (same as if you had no undergravel filter in your tank, you'd still use a gravel vacuum to "clean up" during your water changes) and that is fundamentally the problem with UGF's... unless you remove that waste on a very regular basis it will rot and contribute to ammonia spikes in your tank, which your biological filtration may not be able to keep up with (particularly in smaller tanks, and especially if the UGF is your main means of filtration).

The problems with power filters and bettas comes down to the risk that their fins could be sucked into the intake (which is easily fixed by covering the intake with a pre-filter sponge or pantyhose, or even a small filter bag) and that the current created by the outflow is often too strong - even WITH baffles. Bettas typically don't like strong current and being forced to swim against it constantly stresses them out. 

A powerhead on an UGF would obviously remove the "sucked into the intake" risk but it doesn't at all address the current issue, and creates a bigger problem than it's meant to solve, and a 3g tank only complicates that more (any powerhead would create more current in a 3g tank than a 10g, for example).

For a 3 gallon tank I'd recommend a sponge filter (same concept as a UGF, basically, which you can easily remove from your tank to rinse off once in a while) or a very small internal power filter like the Tom's Aquarium mini.


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## goldfishyman (Jun 8, 2012)

sarahspins said:


> Gravel vacuums don't suck up the waste the accumulates UNDER the filter grid, only what is loose between the gravel itself (same as if you had no undergravel filter in your tank, you'd still use a gravel vacuum to "clean up" during your water changes) and that is fundamentally the problem with UGF's... unless you remove that waste on a very regular basis it will rot and contribute to ammonia spikes in your tank, which your biological filtration may not be able to keep up with (particularly in smaller tanks, and especially if the UGF is your main means of filtration).
> 
> The problems with power filters and bettas comes down to the risk that their fins could be sucked into the intake (which is easily fixed by covering the intake with a pre-filter sponge or pantyhose, or even a small filter bag) and that the current created by the outflow is often too strong - even WITH baffles. Bettas typically don't like strong current and being forced to swim against it constantly stresses them out.
> 
> ...


 I used small gravel inherited from my grandmother with my Under gravel filter when I was a kid. I don't even recall having to cycle the tank, I just put fish in and it never turned cloudy, fish never got sick. It could be because the gravel was used in a lot of fish tank and seeded easily, it had been dried out for over 5 years when I decided to setup a fish tank. I used to put filter cotton in the top of the tube to catch waste. Every now and then I would tear everything apart to clean the tons of poop caught underneath the filter. I would do that just because I felt like it. Maybe 8 years later they came out with reverse flow pumps for Under gravel filters. Debris and poop no longer get caught in the gravel or under the plates. It all gets stuck in the foam prefilter of the reverse flow power head. The gravel becomes a good biomedia with this setup. This is what I do to reduce the flow of my HOB filters http://www.tropicalfishkeeping.com/...ies/how-dampen-filter-flow-your-betta-115070/


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## itsonlybarney (Jun 20, 2012)

The tank I bought came with a UGF and I turned it off the moment I added my Betta. The current from the power head was just too great, and I can't choose the flow rate, so baffles wouldn't really help that much.

I am however contemplating powering my UGF with an airstone rather than the power head. Has anyone tried that approach to using a UGF?


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## NorthernLights (Mar 2, 2012)

*Airstone*

I had an airstone setup with an UGF in a hawkeye 1 gallon for a rescue. It worked very well, but the bubbles did create a fair bit of current in the small tank. I eventually realized this was bothering the fish and stuck a piece of plastic aquarium plant (not sure what its supposed to be, but it looks a bit like a sprig from a fir tree) in the riser tube and it diffused the bubbles nicely. Fishy rewarded me a bit after that with his first bubble nest!

Needless to say, I imagine it'd be better in a bigger tank.


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## goldfishyman (Jun 8, 2012)

Under Gravel filters were originally powered by air pumps. So that can work. I recommend using it in reverse flow mode. It needs a special power head to do this. Amazon.com: AquaClear 50 Powerhead, 270 Gallons per Hour, UL Listed: Pet Supplies This one is pretty powerful but I really like how it works. It can run normal or in reverse flow. This power head sits in the normal position and can switch direction of flow by moving a lever. Other reverse flow requires you to flip the power head and use a sponge filter and adapter. The flow is also adjustable. This is a powerful pump but can be adjusted to flow at a trickle. Here's the thing, in reverse flow water gets pumped into the under gravel plate and water flows up through the gravel into the tank. This setup has several advantages, it will not disturb the surface of the water, waste is not sucked down under the gravel plate and trapped, water flow is baffled because output is pushed throughout the entire bottom of the tank. If you properly tune it, it should not bother your fish and provide excellent bio filtration.


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## Oldfishlady (Mar 1, 2010)

IMO/E-UGF work great provided that they are setup properly and maintained.
You can't use too big or too small gravel or too deep over the plates otherwise they can't do their job. You don't want to use too large based decoration over too much area. You don't want to have any rooted plants. You don't want to use anything that can obstruct the flow through the plates.

It is important to vacuum at least weekly to help keep the plates free of too much debris/mulm-otherwise the beneficial bacteria can suffocate-but this is with any type of filter you use.

Remember-the beneficial bacteria are sticky and adhere to all the surface areas in the tank, in the top layer of substrate and in the filter media-very little are in the water column itself-So removal of all the water will not hurt the nitrogen cycle-but over cleaning or under cleaning can.....

When you vacuum inert gravel-regardless of the type of filter-You should be cramming the vacuum all the way to the bottom for a second or two and work your way around the tank. Vacuuming in all areas you can reach without moving anything or disruption of plant roots. You want to turn the gravel and get some of the mulm/debris-not all of it-but enough so that you don't have a build up since that can suffocate the BB-plus, since the BB are sticky they rely on their food source to come to them and if you have too much mulm/devris the food can't get to them.

Not all mulm/debris is bad or food for the BB-Its about balance...too clean and sterile it is hard to sustain life. Over cleaning can be as bad as under cleaning. You can remove too much good bacteria that help to keep the bad bacteria in check (_this is over and above the beneficial bacteria for the nitrogen cycle_)-usually the bad bacteria can colonize faster than the good especially in warmer water we keep a Betta in-you have both in a balanced system. Then in too clean/sterile system the Betta can't develop natural antibodies.

You don't want a crystal clean tank-but your water should always be crystal clear from all the good and bad bacteria doing their job.

Regardless of what type of filter you use-often they can give a false sense of security when they remove all the large pieces of mulm/debris from the water column...Out of sight out of mind......but it still in the tank being recirculated over and over-its the bacteria that break it down and this bacteria also have byproducts that another bacteria will use. Since aquarium are closed systems we are part of the balance.....Water change and removal of excessive mulm/debris on a regular basis.....

UGF in smaller tank can sometimes be harder to maintain since you need to make deep vacuuming weekly to maintain the plates-but they can still work. Sometimes you need to make the water change in steps due to the amount of water you remove when you vacuum. Vacuum half the tank-then refill with like temp dechlorinated water and repeat-leaving the Betta in the tank. If you remove the Betta be sure and re-acclimate like you should do with a new Betta or 100% water changes-by adding small amount of the new tank water to their holding container over 10-15min or to tolerance-Net-then add back to the tank.

In 3gal tank-I would use 1-2mm size gravel that is about half-1 in deep-decoration that are no more than 3in in diameter at the base. Deep vacuum weekly in all areas you can reach without moving anything and no rooted plants-Plant you could use with UGF-anubias, java moss, java fern should be fine since you would tie them off to something so the roots wouldn't impede water flow though the plates.

With all that said, IMO/E filters are optional with a Betta-especially in the smaller tanks with the long fin males, since the water flow can sometimes be the cause of fin damage and stress that lead to neurotic behaviors and illness-not with all long fin males-but some.....


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## NorthernLights (Mar 2, 2012)

*under the filter plate*

One thing I am not sure about, and nobody has yet commented on, but I am wondering...

Has anyone here ever tried to used a gravel vacuum on the riser tube itself to pull out the gunk under the filter plate? It seems to me that it SHOULD work, but I'd like to know if it really DOES work.


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## Thunderloon (Feb 6, 2011)

You'll see all sorts of arguments about to UGF or not UGF. The simplest truth is that UGF comes from an era when we didn't have sponge filters. 

The issue with plants in a UGF isn't so much about blockage of flow, its that plants need special water treatments in order to grow in aquaculture alone. Such treatment isn't healthy for fish. The UGF disrupts and leeches away the plants attempts to gain mineral nourishment from the stones in the tank.

UGF are highy inefficient. A properly installed and operated UGF will allow you precisely one inch of fish length per gallon in the tank. So five females in a ten gallon tank IF the UGF is working perfectly. I can run a five girl tank with a Lee's sponge - the sponge the size of an table hockey paddle. The sponge is incredibly reliable and can be hidden inside a Terracotta saucer with the pipe out the top. Like I mentioned, UGF was great until we got sponge filters.

UGF require firm circulation around the tank. Up the back, across the top to the front and down the front wall. They rely on this mixing roll in order to evenly distribute the circulation through the rocks. For most fish that's not an issue, for Betta the flow can be distressing and distract them from sleep. You can install a sponge and make the lift pipe end up just below or even above the surface and spill over. Since the bottom rock will only be for catching debris that the sponge doesn't get or for supporting the plants, it doesn't have to be the 3cm thickness and evenly distributed. You can aquascape and add ornaments and plants and all manner of things. Using two smaller sponges instead of a large one can be much more effective than the UGF.

UGF cannot catch fine particulate, it's this very material that builds up below the grid that must be removed so that exotic bacteria doesn't grow in it. Sponges are EXCELLENT at catching this fine material. 

Don't get me wrong... for a little display tank or hospice a UGF makes a simple and easy to use filter. The reason you still find them is they're incredibly cheap to make and store on the shelf. A dollar of plastic in a ten cent box that sells for fifteen to twenty bucks. They're the weakest of filters and the most prone to disruption.

The practice of reverse-flowing UGF was an attempt to keep from having to clean the rocks in the bottom, the theory being you just disturbed the rocks and the sponge on the power-head would catch the debris. So a reverse-flow system is a powered sponge that almost-but-not-quite keeps you from having to sweep the bottom.

In the end the Properly Planted Tank with a sponge filter is the best option for betta. My favorite sponge solution is to get a Whisper 3i and a pre-filter sponge (or use an apple corer on a block sponge) and put em together. Gives you the option to use a fine filter floss as well as the benefits of a sponge.

Another option is the box filter. Tripple flow are nice and come in three sizes, you can stack media and sponge inside them and get excellent results. They're not as straight forward as a bubble lift sponge but they allow for the addition or specialized media like bio-nodules from AC systems that support bacterial growth by providing calcium for the critters. I use sponge and denitrate in my small ones to keep the water changes down. It works for about ten months per 10oz per male betta.

Sponge filter, Aquaclear 20, box filter, NPT. These are your betta options out-of-the-box.


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## Hallyx (Jun 11, 2011)

That was a marvelous explanation, Thunderloon. Thank you.

My experience with the Tetra 3i (bubble-lift, related to sponge filters) is that _because of the poor design _the water only flows over the top 25% of the filter media, leaving the bottom part stagnant.

This can be modified to work efficiently. But why bother when there are many other efficient and adequate sponge filters on the market?


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## NorthernLights (Mar 2, 2012)

*hmmm*

Interesting. I have now done some research on sponge filters, and I'm actually somewhat perplexed. I hope one someone can help me to understand the differences better.

It seems to me that sponge filters work the same way as a UGF -- using air or water to push water out of a tub, causing tank water to flow into the space through a filter medium. The only real difference seems to be that a UGF uses the gravel in the tank as the filter medium, and a sponge filter uses a sponge as the filter medium. 

Since they seem to work on the same concept, it is not obvious to me that the sponge filter couldn't cause the current that is of concern with long-finned betas, especially if you have two of them in a tank. In fact, it seems to me that a sponge filter might cause a more powerful current since the water is being pulled through a smaller area (the area of the sponge) rather than the large area of a filter plate. But the flow pattern would be somewhat similar. In fact, it seems to me that the strength of the current for either would be determined by the size and power of the airstone.

The flow pattern around the tank for a UGF would be controlled by the location of the riser tube -- and on most of the smaller tanks I have seen, the tube is in the middle of the tank, not a corner, so the water flow would not be down one side, across the top, and up the opposite side. It would be primarily down towards the entire filter plate, up through the riser tube, and then out across the entire top of the water. 

In the 1 gallon tank I had with a UGF, this seemed to be shown to be very gentle, since a drop of Quick-Cure (it was a rescue and we were desperate), which is a very distinctive color, diffused slowly throughout the tank. It did not rapidly sink, which is what a strong current would have done to it. 

So this does not square with the above explanations. Maybe I am just very confused.


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## goldfishyman (Jun 8, 2012)

NorthernLights said:


> Interesting. I have now done some research on sponge filters, and I'm actually somewhat perplexed. I hope one someone can help me to understand the differences better.
> 
> It seems to me that sponge filters work the same way as a UGF -- using air or water to push water out of a tub, causing tank water to flow into the space through a filter medium. The only real difference seems to be that a UGF uses the gravel in the tank as the filter medium, and a sponge filter uses a sponge as the filter medium.
> 
> ...



Your right, sponge filters usually cause more current than a UGF. But either one can be harsh if your air is not dialed in properly. Reverse flow removes the need to break down and clean the bottom plate. As for limits that were suggested as 1" of fish per gallon, you just add more gravel and it increases your filtration capacity. The main concern is oxygen concentration. Too many fish or too big of fish for the tank without proper aeration can cause oxygen poor environment. 

I used to filter my 20 foot diameter pond with 35 large koi with just water flowing through 25 lbs of gravel. It pretty much worked by having water flow into the top of the container that held the gravel. The container had a partition that divided the tank in half but had a 1 inch gap from the bottom of the tank. 2 inches from the gap was another plate of glass 2 inches tall that was glued to the bottom of the tank. This was used to keep the gravel from spilling out. This setup created a water flow similar to how under gravel filters work. 

I don't use under gravel filters because I prefer sand or bare bottom tanks. You can actually fill a HOB with gravel and it would work pretty well.


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## RosyFish (Feb 20, 2011)

*Filter Revamp*

"In the end the Properly Planted Tank with a sponge filter is the best option for betta. My favorite sponge solution is to get a Whisper 3i and a pre-filter sponge (or use an apple corer on a block sponge) and put em together. Gives you the option to use a fine filter floss as well as the benefits of a sponge."

Any chance that you can post a picture of what you mean?


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## Hallyx (Jun 11, 2011)

Sounds reasonable. But a Whisper 3i is a poorly designed product which neither filters efficiently nor houses much bacteria. Look and see where the water flows out of the filter. The flow completely misses most of the filter pad. 

The air-pump is weak but, otherwise not bad.

You can get an inexpensive, effective sponge filter form Amazon and other places.

(I must remember to put this on a cut-'n-paste.)


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