Get a proper meter. Don't get a cheap one. This is as cheap as I would go. https://www.amazon.com/gp/product/B082DZBJFB/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
This one is better https://www.amazon.com/gp/product/B01ENFOHN8/ref=ox_sc_saved_title_8?smid=ATVPDKIKX0DER&psc=1
pH Meter, Dr.meter Upgraded 0.01 Resolution High Accuracy pH Tester with Backlit Two-Color LCD Display and ATC, 0-14pH Measurement Range with Data Hold Function Digital pH Tester Pen-PH838 https://www.amazon.com/dp/B082DZBJFB/ref=cm_sw_r_apan_glt_i_N1MBAAEH5WKJBA5E7B55?_encoding=UTF8&psc=1
Been going perfect for over a year.