How to Transition from Your Old Aquarium Filter to the New One
Mixing the old filter media with the new

Why your existing filter media is invaluable
The point is many novice aquarium enthusiasts are in a hurry to do away with their old existing filters,when they upgrade themselves to that new filter they always wanted. In their eagerness to have the new filter installed and running,they miss out on one critical thing.
What's that? Well,they threw out the baby with the bathwater (not literally).What they did miss out was all the crucial nitro-bacter that had colonized in the old filter media was thrown out and the new filter with it's brand new filter media installed instead.
So,what you get is crystal clear water and some days later some fish floating upside down - dead. What went wrong over here? Well, you crashed the ammonia cycle...that's what happened.
The old filter was in fact the heart of the aquarium ecosystem,with all the nitro-bacteria in it,breaking down the ammonia,converting nitrite to nitrates...so when that 'old' filter was removed,the most useful part of the ecosystem was removed with it and the ammonia cycle went out of control in just a few days with almost no bacteria to break down the ammonia build up,the ammonia & nitrite levels peaked...leading to fatalities.
So,how does one avoid this? Simple.
- Remove the existing filter media (Sponge,Ceramic rings,etc) from the existing filter
- Place some part of it along with the new filter media to help colonize the new filter
- Let both filters run in parallel for at least 1 week before you remove the old filter.
This gives the bacteria enough time to colonize in the new filter.
So,that's why you shouldn't throw out your old filter when you get a new one!
Mixing the old ceramic rings with the new

The new setup


Comments
So what do you do if you are changing filters because the old one is broken? Am I out of luck because I can not run them simultaneously?
Run both filters in parallel for a week. That will help the bacteria colonize the new filter, you can move on to the new filter completely after about 10 days.
I'm upgrading filter systems from Aqueon Quiet Flow filter system to a Aquatop UV filter system. This is a significant upgrade. How can I switch out without harming the fish? Thank you
I really like science. i am the guy who frequently posts on ur wall in facebook.
Good post. Everyone should get educated on nitrogen cycles before embarking on this hobby. We'll have less fish fatality then.
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