I have a 5 gallon aquarium with a tetra "whisper" filter that uses bio bags for it's filter media. I changed my filter for the first time yesterday and I'm having issues.
From what I read on here and other sites, the recommendation was to keep the filter until it was falling apart, as long as I "cleaned" it by swishing it around in old tank water during water changes. I have done that every week at water change time (50% WC) and the filter finally needed changing this week. I know that the beneficial bacteria that keep the nitrogen cycle steady live mainly on the substrate and in the filter medium (correct me if I'm wrong). So I cut chunks of the old filter medium off of the old filter and put it in with the new, as many have suggested. Today my water levels are all messed up :( I think I uncycled my tank? Water change yesterday, today readings are-
nitrate 10-20 (they're the exact same color on my chart).
When my water has always been before-
Any ideas on how I can fix it and how to avoid this next time I need to change the filter?
Thanks for your time :)