[Winged Mermaid]

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-
ammonia 0.25
nitrite 0
nitrate 10-20 (they're the exact same color on my chart).

When my water has always been before-
ammonia 0
nitrite 0.25-0.50
nitrate 5-10

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

 

[jaysee]

My suggestion is to get an aquaclear sponge. You can use that as your filter media and never have to change the media ever again. Their sponges are really easy to cut to shape. Too, you can cut the piece you're going to use in half that way you can easily clean half the media at a time to help maintain more even water quality. I would take the old media you have and cram it in there with the sponges so that it can more rapidly colonize the new media.

 

[Winged Mermaid]

Thanks so much! I saw others posting about switching out the biobags for sponges- since apparently the charcoal in the biobags are useless after 2 weeks and the mesh-ish bag does next to nothing- but I had no idea where to find a sponge that would fit. I hopped on google, but it was sponge overload and confusion on where to even start! So thank you very much for your recommendation

It doesn't seem the old filter media I put in there with the new filter is working very well so far in terms of the bacteria colonization. Should I just keep an eye on the water and wait it out to see if it will replenish on it's own, or will that just lead to dangerous water levels for my betta?
I guess I could just bite the bullet and get another thing of Safe Start (what I originally used to successfully cycle my tank), and be sure to have the sponges in there when I put it in.

What do you think? Is waiting to see if the old filter media will colonize the new media a lost cause? I don't know if I'm being too quick by expecting it to recover and just need to wait, or if I just need to call it a wash and get more safe start.