They have a video library of questions like this, go to the web site, look under HELP and put in filtration There are several Aquarium Co-0p videos on filtration such as...how much do I need, what type do I need, what size do I need, do I need more than one type. You can even go to YouTube and type in Aquarium Co-Op filtration and YouTube will pop up a bunch of suggested videos. The videos will answer your question far better than I can explain. So glad you got into keeping some fish and found Aquarium Co-Op, they will teach you so much about any aquarium question or situation you will run into. Aquariums are awesome. Happy Fish Keeping!
They have 20 gallon and 40 gallon sponge filters in the store and on line. If you are in the area, you should head into the store and talk with the staff. They are amazing and so helpful. If you can't head into the store, I would test your water. If you have a lot of nitrites go with the large 40 gallon. The bigger you go the more filtering you have. So you have plants? If you have a lot of plant you could go with the medium 20 gallon. So many things play into which size filter you get. Good luck and enjoy your fish!!
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