Sponge Filter And Hob Filter

Tpane27

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ive been running a fluval c3 filter on my 29 gallon and just added sponge filter for up to 25 gallon. I replaced my decent sized air stone with the new sponge filter. Anyone know if taking away all the bubbles will change the fishes health? The sponge filter releases bubbles, not as many. I had the lights off for awhile and turned the kitchen light on and all the fish were pretty still. Some sitting towards the bottom and some up top. Do you think this new filter addition and taking out the bubbler could have had a big impact or it’s just going from dark to light?
 

CheshireKat

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I doubt it. You're still getting some oxygen from the HOB outflow most likely, and the sponge filter produces bubbles. But if I remember correctly, oxygen enters the water from surface agitation and thus gas exchange, not bubbles in the water, so the amount of bubbles doesn't matter alone.
 

JayH

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But if I remember correctly, oxygen enters the water from surface agitation and thus gas exchange, not bubbles in the water, so the amount of bubbles doesn't matter alone.
Gas exchange with water is largely a matter of surface area. At the top of the tank, the surface area is fixed, with the gas exchange being accelerated somewhat by the moving water. If you have something that produces lots of tiny bubbles, those bubbles will have an absolutely mind-blowing surface area. With a proper air stone you'll get much more gas exchange from the bubbles than from the surface of the tank.

That said, it doesn't necessarily follow that a sponge filter with poor air dispersion will produce the kind of bubbles that will put a lot of oxygen in the water. There are lot of different approaches to generating those bubbles and some are much better than others. The Czech air lift is a very good general design. If implemented properly it will create lots of tiny bubbles that provide an excellent amount of lift. The small bubbles should also provide lots of surface area for oxygen to get into the water.
 

CheshireKat

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Gas exchange with water is largely a matter of surface area. At the top of the tank, the surface area is fixed, with the gas exchange being accelerated somewhat by the moving water. If you have something that produces lots of tiny bubbles, those bubbles will have an absolutely mind-blowing surface area. With a proper air stone you'll get much more gas exchange from the bubbles than from the surface of the tank.

That said, it doesn't necessarily follow that a sponge filter with poor air dispersion will produce the kind of bubbles that will put a lot of oxygen in the water. There are lot of different approaches to generating those bubbles and some are much better than others. The Czech air lift is a very good general design. If implemented properly it will create lots of tiny bubbles that provide an excellent amount of lift. The small bubbles should also provide lots of surface area for oxygen to get into the water.
I guess perhaps I'm being thrown off by the the OP's mention of a "bubbler." I think I was imagining like one of those decorations that bubble like a clam or something, which doesn't typically produce fine bubbles like an airstone.
 

JayH

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I guess perhaps I'm being thrown off by the the OP's mention of a "bubbler." I think I was imagining like one of those decorations that bubble like a clam or something, which doesn't typically produce fine bubbles like an airstone.
When I was researching CO2 for aquarium plants I came upon a device that claimed to produce 27,000 bubbles per second. That was from a single 3mm bubble under high pressure the likes of which you'd never see from a normal aquarium air pump. Doing a bit of math I found those very tiny bubbles collectively had 30 times the surface area of that one rather small bubble. I mention this only to illustrate the point about surface area. You'd never use a bubble maker like that for normal air.

There are some bubble devices (I hesitate to call them air stones) that do produce lots of very small bubbles using a normal aquarium air pump. I don't think quite to the extent of that CO2 diffuser, but way more than the average sponge filter produces.

For a sponge filter I think there's a sweet spot in bubble size. If the bubbles are too small they don't have as much buoyancy and just kind of float through the water. Great for CO2 bubbles, not so much in a sponge filter. You want bubbles with good buoyancy in a quantity that saturates the lift column.
 

CheshireKat

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When I was researching CO2 for aquarium plants I came upon a device that claimed to produce 27,000 bubbles per second. That was from a single 3mm bubble under high pressure the likes of which you'd never see from a normal aquarium air pump. Doing a bit of math I found those very tiny bubbles collectively had 30 times the surface area of that one rather small bubble. I mention this only to illustrate the point about surface area. You'd never use a bubble maker like that for normal air.

There are some bubble devices (I hesitate to call them air stones) that do produce lots of very small bubbles using a normal aquarium air pump. I don't think quite to the extent of that CO2 diffuser, but way more than the average sponge filter produces.

For a sponge filter I think there's a sweet spot in bubble size. If the bubbles are too small they don't have as much buoyancy and just kind of float through the water. Great for CO2 bubbles, not so much in a sponge filter. You want bubbles with good buoyancy in a quantity that saturates the lift column.
Interesting. Although for the average hobbyist and healthy fish, I don't think aeration is too much of an issue, especially for labrynth fish, but there are cases such as with sick fish, sensitive fish, and fish that just come from or are built for very oxygen-rich environments in which aeration is a bigger consideration; and for fish like bettas and others that prefer or come from slow-moving or still water, babies, sick fish, etc., I think the bigger consideration would be water current, movement, and agitation.

Some sitting towards the bottom and some up top.
What I suspect is there might be less water movement or current. Just as we don't need to move or work as much to keep afloat or swim in a still swimming pool compared to a fast river, the fish might not have needed to move or work or work as much after you replaced the bubbler with a sponge filter.
 
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