Under-Gravel Filter?

Well, I am just going to answer the questions straight forward without debate.

The way that the undergravel filter works is this - the tube is connected to the grid, and the airstone is placed inside the tube. As the bubbles rise, it creates a suction current that pulls water from the tank, through the gravel, through the grid, and up through the tube.

Under-gravel-filter.png


I agree that they can be efficient enough to handle a small bioload. However, personally I think a 2.5 gallon aquarium is a bit small, even for a betta. I don't keep them in anything smaller than a 5 gallon.

I would consider getting a nano-HOB, such as a RedSea, to replace it. They are pretty cheap to purchase.

http://www.petco.com/product/12148/...-8381-DE11-B7F3-0019B9C043EB&mr:referralID=NA

These little filters have an adjustable flow rate, which is good because you can lower the amount of current so that your betta is not stressed.

Walmart sells a bulb in their pet department, it is a 10 watt CFL. They are $5.99, and fit perfectly in the socket for these little tanks. In a tank this small, it does raise the temperature a bit, so keep an eye on that.

http://www.walmart.com/catalog/product.do?product_id=10448675

They have these available right in my local store.

Kristina
 
rainbowcharmer said:
I agree about the gravel vac, but the problem I had in that tank was that by the time I started vacuuming the gravel, most of the water was gone before I got much "crap" out from under the gravel. Perhaps my gravel was too thick, but I never was able to get much out of it before I ran out of water in that small of a setup. Maybe in a bigger setup this isn't such a problem? But that hex was just a nightmare. I like my 5 gallon a lot better, even with the in-tank whisper, which I realize is not perfect, but I like it better than the UG filter on the old 2 gal hex. It doesn't take long to run out of water in those 2 gal setups considering there is probably only 1.5 gallons of water actually in them after gravel and decorations. I normally took out 1 gal at a time, which left barely enough room for that betta to swim.
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A hex is actually easier to vac out without taking too much water due to its small footprint to volume ratio. The trick with gravel vacuuming is to use a vac with a small diameter hose, and control the flow by pinching it off. You stick it straight down through the gravel, and let the water flow until you see a band of clear water then pinch it off to stop the flow. Move the vac to the next location and repeat. If the gravel has been neglected you may have to do it in sections over several changes but once it's in decent shape you should be able to pull out as little 10% while getting the whole bed.
 
Thank you all for you're replies!

Kyryah - I have already ordered that nano filter because I didn't really like the under-gravel filter very much :). Thank you for the bulb suggestion I'll definitely pick one of those up to replace that ugly yellow light. I'll make sure to watch the temp though but I have a feeling it will be perfect because my room is rather cold during the day and only gets hot at night when I close my door since it traps the heat in.
I do kind of feel a little bad about him being in such a small aquarium because my other betta is in an eclipse 6 but it is better then his cup. I was hoping that with this smaller tank that I could truck him back and forth to school and such.
 
You can combine the UG with the nano and get the far better biological filtration of the UG with the chemical and added mechanical filtration of the HOB. What you do is replace the tube that the bubbles rise up with one that is long enough to extend out of the water. Then when you mount the HOB position it so its intake tube is inserted into the UG's riser tube. This forces all the water through the gravel before it goes through the HOB.
 
:iagree:

Back in the days UGFs were the best biofilter available, power heads were just far too expencive when available, so I set up my 55gal the same way. Water quality was 100% with a bio load of 2 Oscars, 1 Texas Pike, 1 Blue Gill, and 2 Pleco's. Hob filters have evolved and the newest bestest is a canister, but UGFs have remained unchanged for over 30 years.
I agree, though, that a 2 1/2 gal set up would be to small on it's own. I have both a HOB and a UGF on my 5 gal Hex. I just vacume parts of the gravel bed at a time during weekly water changes.
 
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I am one of the youngsters that always thought the UGF was the pinnacle of good filtration back a while ago. Now I still know that but find them a bit less friendly because other filters have come along far enough in design to actually work decently as biofilters. A UGF is still the best of the commonly available biofilters, second only to a full sump system. The reason is quite simple. The entire substrate is the filter media and when well cared for it just keeps on working well. As a mechanical filter, it also works quite well as long as you clean the substrate before all the nasties get down below the filter plate. If you just ignore a UGF, it will reward you by having way too much get down below the filter plate where it can no longer be reached with a gravel vac. BTW the gravel vacs we use today were originally sold as a way to clean a UGF and people liked them well enough to try them out on gravel that was not acting as a filter.
 
kyryah said:
Well, I am just going to answer the questions straight forward without debate.

The way that the undergravel filter works is this - the tube is connected to the grid, and the airstone is placed inside the tube. As the bubbles rise, it creates a suction current that pulls water from the tank, through the gravel, through the grid, and up through the tube.

Under-gravel-filter.png


I agree that they can be efficient enough to handle a small bioload. However, personally I think a 2.5 gallon aquarium is a bit small, even for a betta. I don't keep them in anything smaller than a 5 gallon.

I would consider getting a nano-HOB, such as a RedSea, to replace it. They are pretty cheap to purchase.

http://www.petco.com/product/12148/...-8381-DE11-B7F3-0019B9C043EB&mr:referralID=NA

These little filters have an adjustable flow rate, which is good because you can lower the amount of current so that your betta is not stressed.

Walmart sells a bulb in their pet department, it is a 10 watt CFL. They are $5.99, and fit perfectly in the socket for these little tanks. In a tank this small, it does raise the temperature a bit, so keep an eye on that.

http://www.walmart.com/catalog/product.do?product_id=10448675

They have these available right in my local store.

Kristina
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The bubbles DO NOT create a suction. The bubbles displace water in the lift tube. The density/weight of the water in the tube is less than that of the water column outside the tube. Since water seeks the same level, the exterior water pushes down thru the substrate and back up the tube, trying to level things out. UGF can handle an extreme bio-load provided you have sufficeint gravel surface area for the bacteria to grow on.

You can do several improvements such as replace the air lift with power head suction on the tube and increase the flow dramatically thru the substrate or even better, go RUGF.
 
Undergravel filter 101: Uneaten food and fish poops drop down into the gravel. The bubbles coming out of your out-take tube also draw water up with the bubbles, thereby pulling water up from under the gravel plate. The water in tank therefore is forced down into the gravel as is the uneaten food and fish poops. Aerobic (oxygen loving) bacteria breaks down the food and poops into ammonia. Nitrifying bacteria, which lives on the gravel, plants, glass & ornaments converts the ammonia into nitrites and then nitrates. Nitrates can only be removed with lots of live plants or water changes - like 10-20% of the tank volume once per week. I'm not crazy about undergravel filters. They tend to build up a huge amount of rotting sludge under the gravel plates this is a large source of pollutants for the tank. Try sticking a siphon on the exhaust tube and get it going and see if it pulls out some brown smelly water from underneath the gravel plate. So that's how it works --but personally, I think an external filter with vacuuming of the gravel is better than these undergravel filters. The external filter and the vacuuming will remove the fish poops and uneaten food whereas with the undergravel filter, it just rots and is converted to other types of pollutants (ammonia, nitrites and nitrates)
 
ODPILOT said:
I'm not crazy about undergravel filters. They tend to build up a huge amount of rotting sludge under the gravel plates this is a large source of pollutants for the tank.
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Originally posted by Oldman 47:"If you just ignore a UGF, it will reward you by having way too much get down below the filter plate where it can no longer be reached with a gravel vac."

:iagree:

My first tank, a 20 gallon hexagonal, had a UG filter. Biggest mistake ever. Lost several fish to finrot and had no idea why. My favs the corys were the most susceptible. :tombstone: *sniff* Kept vaccuuming, water changing, still sick fish. Got another tank, moved all fish, completely disassembled tank and 20 gal UG filter, and was APPALLED at the amount of sludge. My vaccuum didn't even touch the crap because it was too far below the gravel. :mad: Please don't use that awful thing.
 
UGF and RUGF are the best filters out there for the money....to bad most aquarists do not know how to maintain them...
 
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