Hi everyone, I’ve scoured the internet for some fish tank wisdom but haven’t be able to find the answers I really need. I’m hoping you will have some great feedback! I understand filter/tank basics but I am in no means an expert. Two tanks that I care for had the fish removed and the bacteria was not fed for months- so my assumption is that the bacteria died and now the tank needs to be completely re-cycled? This is a 75 gallon tank with a below tank wet dry filter by Amiracle. My major question is what is the best way to continue? Completely clean the tank and let it cycle for a few weeks (feeding the bacteria, right?) before introducing new fish? I feel like I need to clean up all the old dead bacteria to prevent a die off- but just wanted to verify this information... it’s the first time I’ve had to restart the bacterial growth within these more complex filter types. Does anyone have any particular methods they prefer when trying to accomplish this? My other question is there any reason a charcoal bag would be used in a wet/dry filter. Unfortunately, I did not set up these tanks, but I noticed that below the oxygenated shelf containing the bioballs, there is a charcoal bag and a larger sponge. I understand the sponge is there for the non-oxygenated bacteria growth but is there any reasoning behind a charcoal bag there as well? If so, does it need to be changed on a schedule? Due to the constraints of our set up, it’s incredibly hard to get the filter out enough to reach down to that filter bag. Any help is much appreciated!!! The tanks were incredibly healthy, so I’m hoping I can recreate that! Thank you!