Bonus: you get the old filter that we replaced with the new filter,
and some extra parts for the new filter.
You will need to buy
AquaClear 50 Biomax Filter Insert, available from Chewy among other online places,
https://www.chewy.com/aquaclear-biomax-filter-insert/dp/188286
The instructions say to replace this every three months but that's not necessary, you can just rinse it well. The other things should be replaced on their schedule. Instructions included!
Here it is set up at my house. Fish not included, they have been rehomed.
We had an amazing fish, a "common pleco", that grew to 8 inches! It
is a glass cleaner, you may want something like it, or snails, to
keep algae down.
More pictures of the pleco.
Lid also has installed a home built fish cooler, for days when your air-conditioning is not sufficiently functioning, made out of old computer fans.
Note: thermometer not included, I'll use it in a smaller tank. You
will want to get one, easily available at PetSmart or something.