# Sponge filter choices



## pyrrolin (Jan 11, 2012)

I have two different choices for sponge filters for 10 gallon tanks, the price is almost the same so not a factor.

One is rated for up to 10 gallon tanks. The other is rated for up to 20 gallons tanks. The other difference is the one for 20 gallon tanks would require a little trimming of the uplift tube, about an inch or so taken off.

The big question is, is the larger surface area of the 20 gallon one with the uplift tube trimmed down a little still better than the one rated for 10 gallons that doesn't need trimming?

I am assuming the 20 gallon one trimmed would be better but I would like other's opinions.


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## Rigio (Jul 23, 2013)

I would choose the larger one for the extra surface area for BB to grow on


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## Fishfur (Mar 4, 2012)

Bigger is better.. so get the larger one.

Btw, I have learned a few things by experience over the past year that may be of interest regarding sponge filters. 

The type without an uplift tube of any kind make quite a bit of noise and can splash a lot, because the bubbles that come up are quite large. I learned that if you put on an uplift tube, with the top of the tube just barely below the water surface, it will reduce the noise to near nothing as well as cut down a lot on the splashing.

The other thing that really helps with both noise and splashing is if you get the type of sponge filter that allows you to place an airstone inside the core, because the bubbles from the airstone are so much smaller than those from the inside of the filter cores themselves, and are simply much quieter and don't make so much disturbance on the water's surface.

Not all brands allow for an airstone. You have to look at the core that's inside the sponge to see if an airstone will fit. If it will, all you need is a tiny piece of air tubing to stick the stone to the underside of the piece with the air nipple on the top. There's a nipple on the underside as well. Then I run the air line down the inside of the uplift tube so it stays in one place and tends not to get much crud on it. My Nerites love to crawl into the uplift tubes to eat the biofilm and any diatoms that grow in them.

If the sponge filter uplift tube is too short to reach that high, a piece of almost any tube or plastic pipe or rigid clear tubing that will fit onto the short uplift tube solves the problem. You can add one to a sponge filter than has no uplift tube. Not all of them have one.

Last, the longer the uplift tube is, the more efficient the filter will become. The added length of tube improves the function of the filter because the longer the tube is, the stronger the pull of water through the sponge. I have a big one in my 30 G, with an uplift tube I added to it that is about 11 inches long. The tank is 18" deep, so that puts the tube opening just below water level when the tank is full. It is so quiet I can't hear anything other than the low hum of the air pump and while it does still splash some, it's much less trouble than much larger bubbles are. Some mineral deposits from the mist of the breaking air bubbles will be carried by air to any surface close by, and will have to be wiped off now and then.


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## pyrrolin (Jan 11, 2012)

Yeah, I knew the length of the uplift tube makes a difference, that is why I wanted input on larger sponge and shorter tube or smaller sponge with longer tube


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## cape (Jun 18, 2010)

Great post. Would you happen to have a pic of the sponge filters u speak of? Is this the single or dual sponge type?



Fishfur said:


> Bigger is better.. so get the larger one.
> 
> Btw, I have learned a few things by experience over the past year that may be of interest regarding sponge filters.
> 
> ...


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## pyrrolin (Jan 11, 2012)

Right here http://www.aquariumsupplies.ca/sponge-filters-c-1_60_230.html

I use the 40 gallon ones in my 25 gallon breeding tanks


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## Kimchi24 (Mar 22, 2013)

i use seapora 60 along with an HOB filter on my 33


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## cape (Jun 18, 2010)

Thanks for the link. Is there any benefit with this one vs the dual sponge that you suction to the glass? You can get a dual sponge fom eBay for ~$3 shipped.


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## Fishfur (Mar 4, 2012)

I quite like those dual sponge models. I only have one, but it's great. All the others are singles. I find the dual sponge one is nicer in a smaller tank, simply because it does not take up so much space. The two sponges are smaller diameter to start with, and being on the tank wall by suction cup, they don't occupy any substrate space. Assuming one of those double sponges is, say, two inches in diameter, two of them will be at least as good as a single four inch sponge, and possibly better. My math sucks, so I can't actually calculate whether they have more, less, or the same, in terms of surface area, but roughly speaking, the two smaller ones would be at least as good as a single one twice their size.

My double sponge also has an adjustable uplift tube with an 'L' fitting on the end. The 'L" allows you to direct the output in any direction you want, plus you can adjust the length of the uplift tube to suit the tank. If need be you can raise the position of the whole set up by moving the suction cup up or down too, to get the uplift tube as long as possible, or to shorten it for a very small tank. Versatile to say the least, and provided a nice, mild current of water in a 5G tank, which is what I had it in.

I also added a very slender, disposable air stone to the dual sponge model. Despite being disposable, it lasted at least six months, and I've had the composite ones break down in that length of time so it's not so bad. I ran the air hose down the uplift, and set the stone just above where the T branches off to the two sponges. It runs better and quieter with the air stone than without. I closed off the regular nipple you are supposed to attach the air line to with a dab of silicone. Ran great that way. Tank it was in leaked, so it's not in service just now.

I don't have pics of any of my filters specifically, only what might show if I'm trying to take pics of shrimp or fish or snails. But the only differences between one you'd buy new and mine are the additions I make. I add an airstone, if it will fit inside the core, plus either a new uplift tube if came without one, or a longer one if the one it came with is too short. 

I have used both reinforced vinyl tubing and rigid acrylic tubing to make longer uplifts. You could use any pipe or tube that would fit the rim on top of the filter. I've even used two part epoxy to make tubing I had on hand fit better onto the top rim of the filter. I stuck a bead of epoxy putty around the rim, which made it large enough to fit some rigid tube I had handy. It is slightly loose and sometimes gets nudged off if a big snail crawls on it, but is easy to set back in place. I use small, all plastic clothes pins to clip the air hoses to the top of the uplift tubes, to keep them in place and help prevent the uplift tubes from moving around when snails or fish are bumping into them.

If you really wanted to, instead of running the air line through the uplift, you could make a hole near the bottom of the uplift just large enough to squeeze the air hose through it, and onto the nipple. But unless the hose fits snugly, that hole will leak some air bubbles. Silicone would close up any spaces if need be. Done that way, the air hose would not be visible in the uplift. It could be hidden in the corner or bottom of the tank and only show a bit. I've seen one made that way. Frankly I don't care if I see the airline in the tube or not. I try to plant things like vals or Hygro difformis to obscure the tube so it's not so obvious.

I could take pics of the way I have the airstone attached next time I take one out to clean if you want. But all I did was cut an inch long piece of air hose, stick one end on the air stone and the other end on the nipple which is on the underside of the upper filter fitting. All of the single, round, upright type commercial sponge filters that allow an airstone to fit inside that I've seen so far have a circular piece that fits onto the core, which has the air hose nipple on it. So far, there's always been a nipple on the bottom of that piece too. They're more or less reversible. So I simply put the stone onto one nipple, place it into the core and snug up the fitting, then attach the air hose to the top nipple. 

Just take one of these filters apart and it's easy to see how it works. They all come apart, for cleaning and to replace the sponges.

I think Seapora is the brand that has the type of core where you cannot fit an airstone inside. The core in Seapora's filter is made differently and does not allow enough space for any airstone. I have a couple of them and I have to be content with the longest uplift I can use, and no airstone. They are not bad filters, not by any means at all. It just bugs me I can't retrofit them with an airstone inside.


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## darkangel66n (May 15, 2013)

My favorite sponge filters are the cylinder ones with a weighted base and the sponge is up off the bottom of the tank. They are fairly cheap, very good at what they do, and if you do not use an air stone one pump can run a lot of them for multiple tanks as long as the tanks are the same depth.


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## Fishfur (Mar 4, 2012)

Can't argue that stones can affect the work load on an air pump. But it also depends how many stones you are trying to run. I don't find there is a great difference between a stone running by itself or inside a sponge filter.

I have yet to find any single sponge filter that is made to stand on the tank bottom by itself that does not have a weight of some kind on the underside. Even the little Lee ones have a weight, though it's not as heavy as it could be. The ones that are meant to be stuck to the tank wall with a suction cup don't have weights, they don't need one.

Curious as to why several sponges would all have to be at the same depth to work off one pump though. 

I do know deeper water is more work for the pump to move air through, but unless there is a really big difference in depth, don't see why it would matter if the water in each tank wasn't quite the same depth ? Couldn't you just use valves to adjust for the varying depths ? Please educate me !


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## darkangel66n (May 15, 2013)

Of course you can use valves and I was not meaning tanks within a few inches of each other but trying to run several in 12 inch tanks and one or two in tanks 2 or three times as deep.


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## BillD (Jun 5, 2006)

Deeper tanks require more air pressure, as do clogged air stones. If you blow through a clean air stone there should be no resistance. In my opinion/ experience, airlifts with stones move more water. They do add some restriction, which increases as they clog.


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## Fishfur (Mar 4, 2012)

Ah, I see. thanks for clarifying that. 

Clogging of air stones is the main reason I like the new plastic air stones. So easy to clean, and thus keep from clogging, and they don't crumble to bits, like some of the composite ones do. 

Plus they are weighted so they stay down without help, and that is a real blessing in my algae culture bottles. They come apart at each coloured band and can then be scrubbed easily with a toothbrush in just a few seconds and snap back together. They come in various sizes, the only thing I wish is that they were less brightly coloured. Many have bands of bright yellow, red, blue and green. Can't have everything, right ?


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## bob123 (Dec 31, 2009)

I have removed the lift tubes from my sponge filters as I have had a pleco go inside and die. To make the filter effective I use an air stone inside the sponge just above the weighted base works great and no more dead plecos. Also this way it can be used in shallow tanks.


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## pyrrolin (Jan 11, 2012)

interesting way to do it, so you are basically using the hollow part in the middle of the sponge as the tube then I guess


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## bob123 (Dec 31, 2009)

That's correct and I've had no deaths since. Each of my tanks has two of these filters so each water change one can be cleaned and I alternate. Working great for over four years now.


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## Fishfur (Mar 4, 2012)

Fortunately, no fish have suffered as your plecs did. But I get snails in the tubes often enough. Nerites seem to love the diatoms that tend to show up in them at times. I've had one that got a bit stuck at the bottom of the tube, I think he wedged his shell between the tube and the rim on the filter. Had to rescue him eventually, but he suffered no ill effects.

I often set the tubes in the tank for a day or two to allow snails and shrimp to eat any algae that may have grown in them. They do a better cleaning job than I ever could.

I was looking at flourescent tubes the other day. Saw the 'tube covers' they have for some bulbs. The ones for T12 bulbs are quite wide, and while you would have to use something, maybe epoxy putty, to fill in the additional space at the bottom so they'd fit, they would be large enough for many fish to turn around in, where the smaller diameter tubes would not be big enough for that. I am not sure what effect a wider diameter tube would have on filter efficiency though. It might reduce efficiency somewhat, as the air stream would be more widely dispersed in a wider tube.


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## BillD (Jun 5, 2006)

The "stream"of air isn't what makes the lift tube work. The air bubbles in the tube make the water column less dense than the water at the bottom of the filter, so the higher pressure water moves to fill the void created by the less dense water column. You can test this yourself by holding your hand over the end of a tube and submerging it vertically. When you remove your hand the tube will fill from the bottom. I would guess that a larger tube would potentially increase the water movement if you were able to increase the number of bubbles in the column.


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## Fishfur (Mar 4, 2012)

That's really interesting. And of course I've seen the effect you describe with a tube under water. Now you explain it, I understand how it works. I love it when I learn new stuff.


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## BillD (Jun 5, 2006)

It is a misconception that the air "lifts" the water, when in fact it is gravity that is doing the work. Still, it isn't necessary to understand how it works to have it work.


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## Fishfur (Mar 4, 2012)

Too true. If one had to understand how everything works, nothing would.. too many things are too complex these days. But I do enjoy learning how something like this works, and once reminded, I know the theory is something I learned in high school, but had since forgotten. Physics and chemistry were never my fave subjects. Biology, English and History were what I liked best, and thus paid most attention to.

'Course, now I wish I'd paid more attention to both physics and chemistry .


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## pyrrolin (Jan 11, 2012)

That is the great thing about this hobby, always more to learn, often the hard way.


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