once the filter is removed if it is siliconed in is going to be a job getting back in if you are not happy. Are you unable to make a space for the pipes of the external?
Well I love my fish tanks and they always need a tidy so I just plan on better filters, maybe more fish and possibly co2 if I get better lights. Always liked reptiles, had rabbits, cockateils, budgies, zebra finches , dogs(was 2), rats, hamsters, gerbils, goldfish, and now dog, 2 fishtanks(was 3), 2 guinea pigs and a snake. Since going to the reptile place I had multiple plec syndrome all over again. Didn't actually nearly cry this time when I had to leave with nothing due to xmas eating all my funds. I like having clothes and food thanks
I do want to turn my empty 17 litre into a tiny marine tank but safer off breeding snakes I think. Just need to stay away from the cat and dog shelter too so decided on fish instead but then should of gotten another dog.
I totally get your troubles , I have learned to ignore stuff but was in my tank cleaning 3 times a day at one point especially when I kept common plecs.
I just try and enjoy my tanks now even with a bit algae, took a lot of willpower though.