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Carbon Filters?


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Okay, so I have two 12L tanks, one is currently being filtered by a Rena - Filstar iV and the other I brought a few weeks ago has a built in carbon filter.

I've only ever used internal filters (rena filstar) and have no experience with the carbon ones, is there anything i should be doing differently?

There is currently nothing in the carbon filtered tank (HM arriving tomorrow) but its been cycling for a good 2 weeks or more now. I herd somewhere that people say carbon filters should be turned off at night (or turned off at somepoint) because it gets rid of the good bacteria too? At the moment I've just left it on. Also when I replace the carbon (every month or so?) should I also replace the little bio rings too? or is it just the carbon?

thnaks guys =]

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I'm not familiar with the term 'carbon filter', can you link to the product somewhere?

In general, filters should not be turned off. Turning them off stops the water circulating over the various bits and bobs in the media and because your good bacteria need oxygen-rich water to thrive, they can end up multiplying less or dying back if you remove their access to that water. Carbon shouldn't really absorb bacteria. I've had a quick look for more details, but judging by the way carbon works (kind of like a big magnet rather than a sponge) even if it did pick up bacteria, they shouldn't be killed/rendered ineffective. They should just stick to the outside of the carbon and do their job from there. (note the "should"s, because although I'm fairly certain I cannot immediately find any solid documentation to back it up)

Anyway, even if it did get rid of the bacteria in the water column there is very little of your good bacteria there anyway. Most of it lives in sticky little matrices on the surfaces around your tank, so in the gravel and on the tank walls etc. As the carbon sucks up the organic impurities, the bacteria start colonising it in the same way they colonise gravel. Activated carbon is full of nooks and crannies so there is a lot of space for them in there.

Surface movement is important to increase the overall surface area (a 10x10" flat thing has less surface area than a 10x10" rippled thing) which basically means there is more potential for oxygen to enter the water and other gases to leave. If you turn off the filter for periods of time, that reduces the surface movement, which can lead to reduced O2 which can hobble the bacterial colonies and cause problems for fish and plants.

Don't replace the carbon and the noodles at the same time. Actually, you shouldn't have to replace the noodles ever, just swoosh them in tank water to remove the chunky bits and once a year hit them with high pressure water to clear out the debris. If you have to replace the carbon then try not to disturb anything else. Because the bacteria colonise on the carbon, by changing it over you are tossing out half of your biofilter. Unless you need fresh carbon (for removing dye-based meds or for very dodgy water etc), I'd really just leave it there for however long you like acting as small ceramic noodles.

Keep in mind that carbon will suck up organic dye based drugs, additives like IAL, plant ferts, and some other water additives. Generally this isn't a big deal, because once the carbon has reached it's fill it can't keep sucking, but up until that point it is good to keep in mind. ^_^

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Personally.....If you are keeping fighters.....one per tank

I wouldn't bother filtering a 12l tank.....and If I did I'd only use an air driven sponge filter....do a 50% water change once a week and rinse the sponge out in the water you drain from the tank. I'd have lots of plants...hortwort,java moss,java fern, anubias and water sprite are plants that grow in low light and use all the nutrients.

add a few Malaysian trumpet snails to clean up uneaten food and you have a little micro Asian aquatic nano biotype that your fighter will be right at home in....I'd even throw in a couple of shrimp + a Tropical almond leaf... ^_^

Carbon removes organic matter and trace elements.....Good if you want to polish water after medication...but the small bit they give you for 12l tank wouldn't last long and it only remove trace elements plants need....if you replace it every month you are just throwing out the colony of bacteria that has grown on the spent carbon

I don't believe in replacing sponges....you only throw out all the Good bacteria that has colonised the sponge and risk the tank recycling because of the lack of bacteria

If you are keeping lots of fish in small/large tanks then it's desirable to have filtration....fighters in small tanks....lots of plants + regular water changes is my preferred system to maintain top water quality

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