Dawn77

Hi, Im really hoping you can help. I’ve managed to set up my first hot tub with no help from the manual itself, thankfully YouTube was great. Is someone able to please tell me what each of the 3 holes on the outside of the tub actually do and the same for the 2 inside? For the inside ones, all the photos I can find show that the bottom one is for the large filter (which I’ve attached already), but the top one for me looks like it should be some kind of small mound-shaped filter, but when I unscrew the black cap, it’s just a hole?? Any help would be so appreciated.