Cycling/cartridge and many thanks!

[Bettatastic]

I bought a Betta about 3 weeks ago (my first fish ever!) and right after I found out about the need for cycling, filter, pump etc...
Anyways, we started cycling 3 weeks ago (5 gallon tank w/pump, live plants and a mystery snail). I had my ammonia spike, then my Nitrite spike and now I am down to .25 ammonia, 0 nitrite and my nitrates are starting to show up!! YEAH! I had to do water 20% water changes sometimes twice a day...Anyway, fish and snail are fine but my filter (I swish it out in tank water from time to time) is a carbon filter (actually it's 2, feels like there is gravel in it) it came with the tank/pump and after 3 weeks it looks really dirty and is starting to fall apart...
I don't want to ruin my good cultures by replacing it, also don't want to deal with carbon filters in the future...what should I do?
Thanks in advance, I came here 3 weeks ago and got so much great info about cycling!!

 

[threnjen]

What a lovely little tank!! I love it!

As for the filter, what kind of filter is it? Is it a Tetra Whisper? You can buy some custom media and cut it up and get it in there. Some combo like:
Pet Supplies : Aquarium Filter Accessories : AquaClear 20 Nylon Bag, 2-Pack : Amazon.com
Amazon.com : Fluval Biomax Bio Rings - 500 grams/17.63 ounces : Aquarium Filter Accessories : Pet Supplies
Amazon.com: AquaClear 30 Foam: Pet Supplies

Cut the sponge into pieces that fit in the bottom, and put some bio media in the bag on top. You would cut up your current cartridges and put all of the stuff from them in another media bag between the foam and bio rings to help seed them.

You can also keep your filter cleaner by using a prefilter sponge on it like this
Amazon.com : Pre-Filter Sponge 3 Pack for Fluval Edge Aquarium : Aquarium Filter Accessories : Pet Supplies

 

[Bettatastic]

Thanks Threnjen

That's a great idea to dump the carbon and keep the rest!