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my sister is setting up a fry tank because of an un-expected birth, and she is confused about the sponge filter thing. She asked me but i have no clue. her question was: Do you buy the sponge filter separate from the filter, and is it supposed to take in water, then clean it, or blow out air/bubbles?

What came first? the chicken or the egg? No really.....

how much are they and how do they work? any pictures or links?

What came first? the chicken or the egg? No really.....

Be it a sponge insert in a cannister filter, a cartridge of sponge in an internal or just a chunk of sponge on the end of an outflow the principles of how they work are the same, the only variable being efficiency.

Basically sponge is a structure that has a high surface area, that whenever you pass oxygenated water through it traps detritus. Bacteria start to form on its myriad of structures. Sponge works in two ways, first it traps detritus giving a mechanical cleaning function, trapping impurities and keeping the water mostly free of them, but once matured into a stable environment the filtration takes on a different level (namely the cycle) when ammonia consuming , nitrate releasing bacteria start to colonise it, and thats the bit that really keeps fish alive.

Regular decompositional bacteria, much the same as those that work in rivers and wet woodlands across the world, various protists, fungi, microscopic nematodes, protozoa etc all go to work on extracting every last scrap of nutrition , and they produce ammonia and hydrogen sulphide.These bacteria are absolutely omnipresent, and very strong, they reproduce quickly and in warm aquarium temperatures bacterial decomposition is detectable within minutes. The sulphides they produce, in a tank with good aeration and water disturbance simply stay in gaseous form and are exchanged from the surface layer leaving the tank with reasonable expediency, thus not causing much of a problem.

Ammonia, that other by-product of decompositional bacteria, stays in solution, and this decompositional ammonia combined with the ammonia that comes directly from fish respiration, ( fish dont urinate and dont use urates as we and reptiles do, they pass their ammonia in raw form directly into the water every time they take a breath rather than in a heavily mineralised salt in the excreta ) is the main toxic chemical that pollutes aquaria, and its this ammonia that threatens the lives of fish and means you cant keep them in a small body of water without a huge colony of bacteria absorbing ammonia when it is at its most lethal.

The bacteria we want to encourage require a constant oxygen flow. In nature these bacteria are oxygenated by the flow and the massive surface area and huge vegetation content of a river, keeping their numbers high ,even a river with an imperceptible flow would be the equivalent of changing a several thousand gallon tank every second, and your piece of sponge is a way to address the shortfall your average tank has compared to a river.

Even in nature, few surfaces are as porous or have as massive a surface area as a sponge, so by using a sponge and giving it time to mature, what youre doing is allowing a bacteria that can survive only in oxygen rich water with a high flow rate to exist at a much higher level in denser colonies in confined area than even nature can manage. The structure of the sponge, and the reliable flow rate of a filter create a micro-environment in which the bacteria you need can proliferate to levels far above normal, therefore coping with pollution from ammonia that is far higher than normal for nature becuase of the high stocking density, limited surface area, and small amount of available water, porous surfaces, and plants.

So in short , a sponge is an environment designed to maximise the potential of a specific kind of bacteria, and that bacterial colony , though fragile and living under extremophile conditions, is what keeps fish alive, by saving them from the damage caused by their own pollution from their breathing and feeding wastes.

The bacteria do not completely end all toxicity though. They produce nitrate.Nitrate is simply another form of ammonia, which at a conservative estimate is approximately 40 times less toxic than regular ammonia. So in essence what youre doing in echanging one toxin for a less volatile one, and this means of course that even with a sponge filter you still have to perform water changes to avoid the nitrate rising abouve 40 parts per million, which is about the same as 1 part per million of ammonia ( which is fairly universally recognised at the level most fish begin to take respiritory damage to the gills).

So in essence a sponge filter and flow correctly rated for your water volume, and fish stocking level, will basically increase the time you can keep fish alive in the same body of water by about 40 times before having to change out some water, which gives them a stable enough environment in which to survive.

This is also why when cleaning sponges the basic idea is to keep them unclogged, but not too clean, usually squeezing them out into a bucket of old tankwater is enough cleaning. Expose them to chlorine in tapwater, or cut the flow of water and oxygen off for long enough (usually 15 minutes plus) and your extremophile, ammonia consuming bacteria, that you have struggled so hard to maintain, will begin to die. If they die, the fish have to live through a period of high direct ammonia until the colony recovers in around a fortnight to a month. Some may not survive this time, and therefore you can buy bacterial aids to help you if you happened to have completely mucked it up

So in short , a filter sponge is basically a growing medium and a concentrated environment for beneficial extremophile bacteria, and a mesh to catch particles of detritus. It will also contain decompositional bacteria as well and nitrosoma bacteria, and the two colonies work together, thusly creating your all in one , nutrient reducing, crap catching, toxicity reducing environment.

All you have to do is add flow, and maybe an oxygenator and a bit of surface area disturbance to ensure there is reasonable oxygen saturation so the colony stays healthy, and keeps living and growing in density at accellerated rates. Obviously, rather than just having a chunk of sponge on the end of a section of pump powered tubing, it pays to have a nicely designed filter, where the sponge is a nice tight fit, ensuring the water doesnt bypass most of the sponge, or flow rates through the sponge vary too much. That way the total area of the sponge is saturated with bacteria at the highest possible level, and thusly for size, it will be a super-efficient ammonia eating, water cleaning machine But you do have to keep it unblocked, supplied with oxygen,flow, and protect it from harm caused by bactericide medications, chlorines in tapwater, and the ol' electricity giving out. Obviously it has to be fed too, it cant grow without some ammonia, but then it actually requires very little.

Thats either really helped or confused the hell out of you


The other common question is where do these miraculous bacteria come from? Well the answer is, theyre pretty much omnipresent in most enviroments in the world. Theyre in all watercourses, in atmospheric moisture, on aquatic plants and a few will even be on the fish themselves. They have even been detected in serously high level clouds! One way or another, they find their way into any aquarium. The cycle is the period when your waiting for these bacteria to find your filter environment and start to grow into a colony of significant proportions . Handy

Actually I could go into greater detail than that, illustrating the way several dozen species of bacteria work together, in balance with unrelated species, and how environments create preferential colonial conditions from one organism to another, but that would be some seriously, and I mean seriously dry reading.

You can add sponges to other filters but a sponge filter is a filter by itself. You need an air pump to run it and the sponge will come in a little case which hooks by tubing to the air pump and suction cups to the glass. The stronger the air pump the more bubbles and more circulation. The larger the sponge the more surface area and the more bacteria and detritus it can hold. That determines how much water your sponge can filter successfully. Sponge filters though are considered the weakest form of filtration. They provide very little current and do not pull in water. They are good for fry for that reason and will not suck in anything living. In fact baby shrimp have been known to live on sponge filters and eat the detritus without any harm coming to them. With any stronger filter they would be sucked in and destroyed by the impeller. Because of the low current sponge filters also will not clean the water very well. Most fish waste and food will settle to the bottom and never reach the sponge. Sponges are good for aeration and biofiltration but not mechanical filtration. Frequent gravel vacs are needed to remove the detritus that the sponge does not pick up.

Cost varies depending on the size of pump and sponge you get but you can probably get a cheap setup for a small tank for under $10.

Yup, shams right, a sponge filter of your basic " bit of sponge parked on the end of a suction tube" type, only provides bacterial filtration, there isnt enough flow to pick up much detritus. Obviously it catches some,perhaps enough to keep the water running clear, the discolouration will soon show you that, but apart from raising fry or invertebrates there pretty much isnt a use for them because all the detritus generally settles on the floor of a tank. Nobody really wants to live with that level of cleaning day to day, you'd never never have your arms out of the aquarium!. Sponge in a filter however does provide a good deal of mechanical filtration, simply because large detritus cannot pass throught it. Thats why canisters are packed in layers, preventing them from clogging almost immediately. Often alongside sintered glass rings, biologically active pellets and ball, brushes, etc there will be several layers of sponge from a blue , loosely holed and tough re-usable version, then regular sponge, and then often a fine nylon wool or carbon for even finer filtration. A lot of simple and cheap internals use just one grade of a sponge. Obviously you get what you pay for. Basic sponge filters are even less effective than undergravel filtration, those sponges housed within an internal filter will be more effective, often with even the cheaper filters having an idditional layer of blue foam or carbon, and then theres the externals, which with anything up to 8 layers of different media provide pretty much the ultimate level of filtration with little or no media bypass.

Pics and aussie type prices on sponge filters

Prices should be similar in us Canada EU ect. They're cheap enough that if you do need to toss it due to any illnesses (hopefully not the case with the fry!!!) it's not a huge loss.

^_^

Hi,
If you go to the drsfostersmith.com site and choose
fisn, then filters, then internal filters, you will come
to this site:

http://www.drsfostersmith.com/product/NavResults.cfm?N=2004+113424

The filters titled "Oxygen Plus" are samples of sponge
filters that are absolutely Ideal for fry tanks and these
are sold in the States.

Frank


-->>> The Confidence of Amateurs, is the Envy of Professionals <<<--

^^ use something like that with young fry. the 'suck' is weak and spread over a large area and the sponge is too fine for them to get trapped. I take the clear plastic tubes off the top of mine in shallow tanks to make sure that the water surface is broken (ripples on the surface give better gas exchange, so more oxygen in the water) but if your tank is deep enough to have the tube, leave it on as it seems to increase the suction a little.

You need to buy/have the following for a sponge filter to function:
1 x air pump
1 x sponge filter
1 x piece of airline tubing (no longer than 4' if you can help it, you need a drip loop, but the shorter the tube, the better)
1 x one-way valve (stops water sucking back into the pump if it is turned off, otherwise you have a mini-syphon)

They work because of the bubbles. As the bubbles come out of the middle they drag up a whole bunch of water with them. Think of water like a whole bunch of people holding hands, and they aren't allowed to let go. When you drag that chain of people (the water) up with the bubbles, it pulls all the way down the line. The only place it can pull other people (water) through is through the holes in the sponge. The water flows through the sponge fine, but the muck gets stuck in the sponge.

As long as the bubbles keep happening, the water keeps pulling through the sponge. That means that most of the small muck will keep getting stuck in the sponge. Also, the bacteria that keep your tank healthy love water that moves a bit, because moving water tends to have more oxygen in it, so they'll start nesting in the filter and eating all of the tank nasties for you

All you have to do occasionally (once every 3-4 weeks should be enough) is take the sponge piece out and swish it around in the old tank water when you do a water change. This gets rid of a lot of the muck that will be cloging up its holes so that the water can pull through more easily.

Avoid the Smallworld and Disposable filters that clip on to the little holders. They are death traps for egglayer fry and don't really have enough surface area for bacteria. Also avoid UGFs because the ideal size of gravel is also just the wrong size for fry safety. The fry tend to get sucked down in the gravel or stuck under the plates, and getting them out is not easy as you risk crushing them.

Best of luck!

BTW, what sort of fry are they?

For animals, the entire universe has been neatly divided into things to (a) mate with, (b) eat, (c) run away from, and (d) rocks. - Terry Pratchett