# Can adding a new filter cause ammonia spike?



## RB99 (Feb 22, 2009)

I have an established 100g malawi tank with 21 fish (juvenile & adult). Ammonia always read zero until I recently added a second Marineland C-360 filter. Before adding it I did a 50% h2o change, added Novaqua, salt, pH buffer, cleaned only the sponges in the established filter and rearranged rocks to vacuum hidden waste. It's been a week and I still show an ammonia spike. After the first day I added Amquel and used a powerhead for aeration and the fish resumed normal breathing and activity. I've subsequently performed a 25%, and 10% change and switched ceramic media between the 2 filters, but still show ammonia from 2-5 ppm. The pH is 8.0. It seems like my tank has started a new ammonia cycle. Any suggestions?


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## KaiserSousay (Nov 2, 2008)

New filter + the disturbance of the bacteria on the rocks, sand, etc.=you are into a mini cycle.
I would do no more than continued water changes with a keen eye on ammonia levels as well as nitrite, nitrate.


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## Howler33 (Dec 10, 2004)

The only thing I would add to KaiserSousay's advice is to not feed your fish for a few days to allow your bacteria to catch up to your bioload.


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## JohnB_2 (Jan 7, 2009)

Adding a second filter should not cause an ammonia spike if the first filter is established....


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## sleepy09 (Jan 15, 2009)

> Adding a second filter should not cause an ammonia spike if the first filter is established....


I agree.......

It sounds like to me that you over cleaned your old filter and the tank before you added the new filter, which is what caused the mini cycle.


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## prov356 (Sep 20, 2006)

sleepy09 said:


> It sounds like to me that you over cleaned your old filter and the tank before you added the new filter, which is what caused the mini cycle.


I'd agree with that too. Adding a filter does not create ammonia spikes. Neither does cleaning under 
rocks. Only leaves the filter cleaning. The moving of the biomedia can only add to the problem. Best to 
leave it alone. Continue the water changes and go easy on the feeding until it passes. 2-5ppm is in 
the very dangerous range. You might want to avoid trying to raise the pH right now too. Ammonia is 
more toxic at higher pH levels. Keep using a detox product like Amquel.


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## RB99 (Feb 22, 2009)

I'm back to normal now. Stopped feeding for 4 days and another 25% h2o change. Thanks for the suggestions. I cleaned too much when I added the new filter and probably lost a lot of bacteria.


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