In my opinion filtration factoring should be like anything else that you are the one that decides how much is enough based on your stocklist and their biomass along with how much surface area you have to colonize with, plant compensation and amount of water circulation/ aeration you have and how much effort you're ok with putting in each day/ week/ month. That being said- I have a 50g with a stocklist that consists of more fish per gallon than would take to fill a 60g and then some (in the middle of my final growth upgrading/ separating) but my tank is fully planted and fully layered- should be my profile pic- plus I'm running an ac110, whisper 40i, 3 fluval U3s and a fluval nano, but then I have my coldwater tank up and running perfect on 2 magnum 350 canisters and a penguin power filter and it's a 90g, I would say start with twice the filtration needed and work your way up from there. Same with your stocking, start with your smallest species and don't add more than 5 at one time and wait a week for your tank to balance before adding more... Hope this helps!!
