https://www.amazon.com/gp/aw/d/B019A8A6KQ?psc=1&ref=ppx_pop_mob_b_asin_title I use these test strips with no issues at all.

Amazon also offers Spa gaurd chlorine granules and MPS shock. If you buy the 3 pack of each you save a good bit of $.

https://www.amazon.com/gp/aw/d/B077ZCQPN5?psc=1&ref=ppx_pop_mob_b_asin_title

https://www.amazon.com/gp/aw/d/B01M0YCXEK?psc=1&ref=ppx_pop_mob_b_asin_title