so sorry i am not fan of the filters and i don't like to cycle my tanks. I have all my tanks uncycled. Put your question on main board so you can have more advice . Let me know if you still have problem and i will try to ask someone else on this forum. It took me so long to write to you because i was trying to find the link that i saw about filters and i also was trying to find out more information because i am really not experienced with filters. Remember to baffle it up , sometimes betta can stock in the filter be careful. And i do have a few links from this forum about how to baffle it:)
Ok then you need to do weekly 50% water changes with gravel vacuum . Check the water parameters and do additional water changes if you need to depending on the test reading. About filter, cartridge:If it is an "all-in-one" cartridge that is filter floss with carbon inside, just rinse it once a week in tank water or dechlorinated water. Most of the filters use those kind of cartridges. If the cartridge becomes too old or starts to fall apart, put a new cartridge in the filter but keep the old one behind it for a week and monitor for ammonia spikes.
I personally also like more water changes so i even would recommend 1-50% and a few 25% a week water changes.
I am going to pm you a link from this forum also about water changes, cycled tank care. And i already pmed you acclimation, i din't know if you going to do 100% water changes or 50%.
Ok there is two ways of the water changes. One if you want to cycle the tank meaning that you need to monitor the water parameters, clean the filter media weekly, do weekly 50% water changes . If the water parameters for some reason will higher then it should be you will need extra water changes, and when you cycle the tank you need to have siphon to vacuum the gravel.
Another way when you don't cycle and then you can take filter out and just do regular water changes which i would recommend to alternate 50% one week and 1-100% another week.
So let me know if you want to cycle or if you just want to do regular water changes and i will give you more hints.
Now about betta in the bag i am going to pm you about it. It call betta acclimation. So i will give you a few ways how to do it. And it too much to write in the visitor mess so i am going to pm you. And let me know which way you want water changes so i can give you more information.
So I have a 5 gallon tank with a filter. Is it right that I should change 25-50% of the water once a week? Also, after buying the fish itself, I should let the bag sit in the new water for about an hour before letting the little guy in, right? Thanks!