# Switching Filters on an Established Tank



## bdement (Jun 4, 2007)

Hey everyone, I have a well established (3 year old) 46-gal planted tank with a full bio-load. I've recently purchased and setup an Eheim 2217 to replace my Penguin Bio-Wheel 350. I was worried that I would lose all my biological filtration if I removed the Penguin filter straight away, so I've been running them in parallel for about 2 weeks now. About how long will it be until the Eheim is ready to take over all of the biological filtration duties? Thanks!


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## houseofcards (Feb 16, 2005)

bdement said:


> Hey everyone, I have a well established (3 year old) 46-gal planted tank with a full bio-load. I've recently purchased and setup an Eheim 2217 to replace my Penguin Bio-Wheel 350. I was worried that I would lose all my biological filtration if I removed the Penguin filter straight away, so I've been running them in parallel for about 2 weeks now. About how long will it be until the Eheim is ready to take over all of the biological filtration duties? Thanks!


I wouldn't worry about it. If you have a fullly planted tank of that size most of the biological filtration is inside the tank anyway, especially since all you had was an HOB.

Oh and welcome to APC!


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## mikenas102 (Feb 8, 2006)

Like houseofcards said, most of the bio-filtration for a planted tank is on the plants themselves. However you should take all the media from the Penguin filter and use it in the Eheim at least for a week or two.


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## net (Mar 27, 2007)

depends on how you packed the eheim. I assume the eheim you bought came with media. If so and you used it, run it for a month and that will be good.


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## jazzlvr123 (Apr 29, 2007)

if your plant bioload is great enough most of the biomass will take place in the aquarium, once you have an established aquarium with controlled pps dosing the biomass in your filter can be completely removed i know a lot of pros with great looking tanks that only use their filter simply for water circulation. because once you have a substantial bio load all of the harmful stuff that would normally be consumed by beneficial bacteria in your filter is taken in by the plants, if you are not at that point yet i would consider poring as much of the "dirty" water from your old filter into the new one and maybe even put the dirty cloth from your old filter in to the new one. this will establish a colony of beneficial bacteria in your filter column in a couple days rather than a month.


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## K20A2 (Aug 12, 2006)

I did this exact same thing about 6 months ago. My thinking was that everything would be ok because the plants are handling the bio load. Apparently I was wrong.. HAHA

I took my HOB filter off and replaced it with an eheim 2217, and man did I develop a case of green water, and brown algae across all my plants. This took almost three weeks to correct and was a major pain. I didn't change a thing on the tank except for the filter. I would say play it on the safe side and put the media from the established HOB in the canister to keep things rolling.


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## Phaturkey (Jan 15, 2007)

I had the same problem as K20A2, i thought most of my plants handled the bioload, but when i switched from a hangon to a Eheim Classic I got a bad case of brown algea destroying most of my plants. I say just cycle them both for a week or two and just cut off the old filter then, just to be safe.


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## JERP (Feb 4, 2003)

You're doing the right thing by running the filter in parallel anyway. You new filter is well established after two weeks. Wait a few days after decommissioning the old filter before doing a water change. Changing both the water and filter at the same time is badness.


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## bdement (Jun 4, 2007)

So, to close the loop on this one: I'll never know. I've decided to keep the Penguin and run it during the night. I don't get a lot of surface turbulence during the day from my spray bar, and I felt like there should be some at night to oxygenate the water. 

The morning after the first night I went without the HOB running, I found a cardinal gasping at the top. It died later that day, from old age as far as I can tell (~12 months), but that still feels like a clue, ya know?


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## jazzlvr123 (Apr 29, 2007)

did you add any of the bacteria for your old filter to the new one? what it sounds like is a spike in ammonia or nitrate that killed your tetra these spikes are normal this first month if you do not have any beneficial bacteria in the filter. it is recommended to keep fish that you wont mind losing the first couple of weeks if you want to establish you filter with out s\adding any dirty water from the old filter. the advantage to waiting it out is you have a colony of bacteria in your filter that is specialized in decomposing toxins in your new tanks environment not the old one.


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## bdement (Jun 4, 2007)

jazzlvr123 said:


> did you add any of the bacteria for your old filter to the new one? what it sounds like is a spike in ammonia or nitrate that killed your tetra these spikes are normal this first month if you do not have any beneficial bacteria in the filter. it is recommended to keep fish that you wont mind losing the first couple of weeks if you want to establish you filter with out s\adding any dirty water from the old filter. the advantage to waiting it out is you have a colony of bacteria in your filter that is specialized in decomposing toxins in your new tanks environment not the old one.


Well, I never actually cross-pollinated the media or anything, but I did run them in parallel for 3-4 weeks.

My Penguin makes a lot of racket (I think I have an old peat granule in the impeller, or the impeller's about to break, and probably both, lol), so I unplugged it one evening and left it off until the next morning when I found that tetra. No other fish seemed affected at the time or that day. What you're saying could make sense though, even a small spike could be too much for an already weak fish. Could it have happened that fast, overnight?


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## houseofcards (Feb 16, 2005)

jazzlvr123 said:


> did you add any of the bacteria for your old filter to the new one? what it sounds like is a spike in ammonia or nitrate that killed your tetra these spikes are normal this first month if you do not have any beneficial bacteria in the filter. it is recommended to keep fish that you wont mind losing the first couple of weeks if you want to establish you filter with out s\adding any dirty water from the old filter. the advantage to waiting it out is you have a colony of bacteria in your filter that is specialized in decomposing toxins in your new tanks environment not the old one.


Guys, by bedement's own admission he has a 3-yr old well established planted tank. I seriously doubt there was really any cycle on a tank of that size. Several times I turned off my filter on my 72g and forgot to turn it back on never had an issue. The only difference I noted was more pearling. Why is this? Because the beneficial bacteria in my filter that died with the filter turned off weren't consuming the extra oxygen in the tank. This created a surpass thus the pearling.

A single cardinal dying could be for any reason and doesn't indicate a problem at all.


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