Which filter do I need for my H2O hot tub?

1000 Series - Large filter
2000 Series - Medium filter
2500 Series - Large filter
2500 Series (2018-on - check before ordering) - Small filter
2900 Series - Large filter
3000 Series - Medium filter
3500 Series - Medium filter
4000 Series - Medium filter
4200 Series - Medium filter
4500 Series - Medium filter
500 Series - Medium filter
5000 Series - Medium filter
5500 Series - Medium filter
6000 Series - Medium filter
7000 Series - Medium filter
Coral - Small filter
Just For 2 - Filter 103
Pure Bliss (Not Bliss) - Filter 103
Retreat - Small filter
Retreat Bay - Small filter
Retreat Bay XL - Small filter
Retreat Plus - Medium filter
Retreat Pro - Medium filter
Vortex - Small filter