CraigyD

Hi there, ive recently just changed my filter i have added a external cannister filter to my tank and the guy at the shop told me 2 start using it while still running my old one. I have now experienced high ammonia and nitrite levels. Shud i of put sum filter media from my internal into my external? I dont want no harm for my fish i shud of always had an external **** it. Any help would be appreciated i have a near 300 litre freshwater tank.

jdhef

If you replaced the filter media in your internal filter at the same time as (or shortly after) adding your cannister filter, you basically removed all of your bacteria. Most of your bacteria lives in the filter media and if you replace it you will go thru a mini cycle.

I don't see how putting media from your internal filter into your external will help, since you are using both filters. I think you are just going to need to do daily 50% water changes and keep using both filters until you get through the mini cycle.

CraigyD

Nah i hadnt replaced the media for a while.. Yeh al jus hav 2 see if i can get through it wif no casualties lol cheers