The test strips you need will depend on whether you are using chlorine or chlorine-free chemicals.
If using a chlorine system, the test strips test for chlorine, pH, Alkalinity and in some brands the calcium hardness. For example Zodiac Test Strips 3 in 1 or Insta Test Strips 4 in 1.
If using BioGuard Armour Spa Sanitiser, the test strips test for Bromine, Chlorine, pH and Alkalinity. For example BioGuard Test Strips 6 in 1.
If using Hydrogen Peroxide, the test strips test for Alkalinity, pH and Calcium Hardness. For example Poppit® 4 Way Test Strips.