A few days ago, my filter started to overflow with water. My moms boyfriend took it apart and threw away all the filter media. It’s been two days since then and my tank has been running on a filter rated for up to 20 gallons (it’s 55 gallons, i just had this set up as a small backup). I was just notified of this today. I need to buy a new filter now (this wasn’t the first time it’s overflowed), and I don’t have any of the old media. I have a small filter running with a little bit of filter sponge but that’s it. What should I do to avoid a big crash?