Hi, first time poster here.

I came into possession of a 125 gallon tank that has a wet dry filter hard lined into the bottom of the stand. I want to remove the bio balls and replace it with bio glass media, carbon and a polyfiber filter, and I want to also give it a really good clean, as it looks like the previous owner neglected to do any routine maintenance on the sump. However, because the sump was hard lined into the bottom of the stand, and because the sump is actually larger than the size of the access door in front, there doesn't seem to be any feasible way to do routine maintenance on it.

Here's a picture, to give an idea. Don't mind the highly cloudy water, that part isn't actually going to be an issue.



Any thoughts or ideas on how to get into this thing to make it more to my liking, and to be able to maintain it regularly? Any ideas would be greatly appreciated!