This is gonna be long but I’d appreciate any help you can give...before you all judge me I would like to simply appologize. I’ve been on this site for quite sometime now thinking I’m finally learning the basics. But everytime I get a step ahead, I feel as if I fall a million steps behind. In no way do I mean to harm my fish, or sound like an uneducated, careless fish mom (lol). I’m just simply trying to do everything correctly so I appreciate all the knowledge.. A little back story: 20 gallon tall tank for about a year or two. I have a hang on back filter with all 3 media ( the brand is aqueon) as well as a heater. The tank has two thermometers. It also has a few plants, deco, and rocks in which I planned redecorating until this happened.. A local fish store was telling me that I should never change the filter media and I should swoosh around the sponge, and change the carbon every now and then.. since I’ve has this tank I’ve never changed anything.. not the sponge. Not the carbon. Nothing. So the same media has been in the tank for around 1-2 years without being touched. Now comes the even worse part; I’ve been noticing my little guy acting weird lately, but he’s never been that active so I figured he’s just getting older or chilling out. Until today, I noticed the entire filter was not working. This could have been broken for 3-4 days and I didn’t even take notice.. Anyways here is what I did; Took apart the canister and cleaned it out (it stared working perfectly fine again) As for the media: I rinsed the sponge and then put it back I put the same media back And I put a BRAND NEW carbon bag in The tank was completely covered in little floating debris so I went ahead and did a 40-45% water change ( I have extremely high ph so I can’t do massive water changes all at once ), I also used seachem water conditioner. My question is, where do I go from here? My little guy is on his side and I feel like an awful person. In no way did I intend for any of this to happen. Like I said I’m just trying to get the hang of this whole thing and make him happy. Any help would be immensely appretiated. Again, thanks for all the help and thank you for reading. PS: 1 Beta in the tank, nothing else. If it works out I may add 1 mystery snail. If it somehow matters, I do weekly water changed of 30%, if the tank is dirty I’ll do more. Again, thankyou.